AltaGas
Submitted 09/02/2026, 03:03 pm
Submitted on behalf of
AltaGas/Blythe Energy Inc.
1.
Please provide your organization’s comments on section A. Transmission Service to eligible customers.
a. Please provide comments on the definition of large loads.
b. Please provide comments on the large load application process and interconnection study procedures.
c. Please provide comments on the large load operational requirements.
d. Please provide any other comments on this topic
a. Please provide comments on the definition of large loads.
As the Straw Proposal states, FERC suggested a potentially reasonable definition of Large Loads (LLs) as “a new commercial or industrial customer, located at a single site behind one or more points of interconnection, and that has a peak load of 50 MW or greater, interconnects to the transmission system at a voltage level of greater than 69 kV, and is not part of a co-location arrangement. (Straw Proposal, pp.8-9)
CAISO suggested that a potential Large Loads definition could be: “An End User located at a single site interconnecting to the CAISO Controlled Grid, and that has a peak load of 50 MW or greater.” (Straw Proposal, p.9).
AltaGas agrees with the CAISO’s position that it is not necessary to restrict the customer types qualifying for the LL definition, and that specifying connection to the CAISO grid is preferable to a voltage requirement.
AltaGas also agrees with the CAISO’s proposed inclusion of LLs in co-located arrangements. As noted below, these arrangements have the potential for economical and timely LL interconnections in locations that offer significant benefits for the grid.
However, AltaGas is concerned about FERC’s and the CAISO’s use of the term “site,” compared to the more restrictive “premises” definition that PTO tariffs typically apply to loads. The “site” term is preferable to the “premises” term, as explained below.
Neither the CAISO tariff nor the PTO tariffs has a definition of the term “site.”
The CAISO tariff does, however, have definitions that use the term “site” – Site Control and Site Exclusivity. Those terms refer to a Generating Facility site, which can span hundreds or thousands of acres, with few other restrictions other than a common interconnection.
This flexibility is allowed for Generating Facilities because development of large generation/storage projects may require assembly of numerous properties, and adjustment as design, permitting, and construction commence. It is likely that development of LLs will also require multiple-parcel acquisition, and the same definitional flexibility allowed for large Generating Facilities.
By contrast, PTO tariffs applicable to load seem more restrictive with respect to load location. Electric Rule 1 – common to the PG&E, SCE, and SDG&E tariffs – uses the term “premises:”
PREMISES: All of the real property and apparatus employed in a single enterprise on an integral parcel of land undivided, excepting in the case of industrial, agricultural, oil field, resort enterprises, and public or quasi-public institutions, by a dedicated street, highway or public thoroughfare or railway. Automobile parking lots constituting a part of and adjacent to a single enterprise may be separated by an alley from the remainder of the Premises served.
It may be difficult or impossible for an operating generator to add a 50MW or more load to an existing generation/storage “premises,” at least without augmentation of land acquisition or rights. Thus, it is important that the PTOs also accept the CAISO’s “site” construct for LL definition, and not unduly constrain it definitionally to the more restrictive “premises” term.
It is also important to allow for expansion of the existing generator “site” to accommodate the new LL under this construct. It seems unlikely that a load of 50MW or greater could be added to an existing generator “site,” so reasonable expansion should be permitted.
Finally, there is no reason that the physical location of these facilities need be limited to a single site or premises, as long as they share interconnection arrangements (see below).
b. Please provide comments on the large load application process and interconnection study procedures.
The discussion at the stakeholder meeting was rather confusing, especially with respect to treatment of coordinated LL and generation/storage. The conclusions AltaGas took from the meeting about the study process are summarized below, and some clear statements and examples in the next Proposal iteration would be helpful.
- Stand-alone LLs would interconnect under PTO tariffs (TO Tariff, given inclusion of the CAISO Grid in the CAISO’s definition).
- New LL-generation/storage combinations not planning to discharge energy into the grid would interconnect under PTO tariffs also. This is the case even though there will be times when the associated generation/storage capacity may be de-rated or on outage, so the load will require service from the grid.
However, the CAISO said at the meeting that these combinations could modify their facilities, and it’s not clear whether that ability could increase their generation/storage or decrease their load (perhaps even below the 50MW threshold) such that they may discharge into the grid.
- New LL-generation/storage combinations planning to discharge energy into the grid would interconnect under the CAISO tariff, including cluster-study processes and listings in the queue. However, it’s not clear how the new, Order 2023-based intake and study rules would apply to these combinations.
For example, the scoring rubric applicable to the competitive intake process does not consider loads, only resources. Assignment of Commercial Interest points, for example, may not make sense where resources will also serve on-site load, and points for location in RA-deficient areas may not be helpful if additional load is offsetting additional resources. Moreover, location of additional load in Merchant Zones may actually be beneficial, so study-area designations may be different depending on the balance of resources and loads in the combined project.
Thus, at a minimum, the CAISO should modify the intake scoring rubric to consider load-related factors and appropriate scoring bases for co-located LL-resource combinations.
- Existing generators planning to add LLs to their current interconnection arrangements would interconnect under TO Tariffs:
If an online CAISO generator seeks to add a large load to its site, the developer would submit the large load interconnection request to the PTO pursuant to its tariff. When ready to reflect the large load, the interconnection customer could request a post commercial operation date (COD) modification or use the Master File change process as needed to assess and capture changes currently allowed under these processes The CAISO, PTO, and interconnection customer could likewise amend the generator interconnection agreement to reflect the large load and any configuration changes. (Straw Proposal, p.32)
However, the application process is not clear if a resource adding a LL to its site might still discharge energy into the grid (see discussion below about RA status retention for the resource). This would seem similar to the above situation where a new LL-resource combination would inject energy into the grid, but that new combination type must apply under CAISO tariffs.
c. Please provide comments on the large load operational requirements.
AltaGas has no comments at this time.
d. Please provide any other comments on this topic
An issue related to the addition of LLs to existing generation/storage sites is conversion of existing generation to “behind the interconnection” service to new LLs, and the impact on their current deliverability and NQC Listings.
In the past, the CAISO has seemingly had only two models for generation: (1) direct grid connection, where a generator has Must Offer Obligations and must follow CAISO Dispatch Instructions; or (2) “behind the meter” (BTM), Net-Energy Metering (NEM) or similar arrangements, where the generation only serves on-site load and never follows CAISO Dispatch Instructions. The former qualifies for inclusion on the NQC List and separate RA status, while the latter does not.
This new LL framework, combined with consideration of flexible LL options, offers the opportunity to consider a different model – generators that primarily serve associated load but (through curtailment of the load or other means) may offer into the market and/or follow CAISO Dispatch Instructions when needed, and thus may be permitted to retain their NQC List and RA status.
In addition, the CAISO said in the meeting that such generators “leaving the grid” to serve associated loads must go through the CAISO resource retirement process, and then clarified that the CAISO would at least need the opportunity to examine the change to ensure no significant adverse RA impacts.
Under the proposal here, the resource would still be operational and would still offer similar or the same RA benefits, so requiring adherence to the retirement process would not be appropriate.
2.
Please provide your organization’s comments on section B. Framework to prevent cost-shifting.
a. Please provide comments on roles and responsibilities to prevent cost shifting.
b. Please provide comments on data transparency.
c. Please provide any other comments on this topic.
- Please provide comments on roles and responsibilities to prevent cost shifting.
AltaGas believes that the same rules could apply to LLs as other loads, and any specific concerns should be identified and addressed based on individual situations. Load requirements to fund upgrades to serve them, subject to line-extension and free-footage rules based on expected revenue, can also apply to LLs.
To the extent that LLs are served by on-site generation, e.g., in co-location arrangements (especially those in more remote areas – see below), they will be using existing facilities and are less likely to require large upgrades. The cost of any upgrades needed for standby or back-up arrangements (to the extent that the loads would not curtail in those situations and thus do not need such arrangements), can be recovered in the rates charged for such service.
- Please provide comments on data transparency.
AltaGas does not object to typical data provision to CAISO for LLs (and, where applicable, co-located generation serving those loads).
- Please provide any other comments on this topic.
AltaGas has no other comments at this time.
3.
Please provide your organization’s comments on section C. Requirements for co-located arrangements.
a. Please provide comments on terminology.
b. Please provide comments on serving co-located loads.
c. Please provide comments on cost allocation for co-located loads.
d. Please provide any other comments on this topic.
a. Please provide comments on terminology.
FERC defined “co-located load” as “end-use customer load that is physically connected to the facilities of an existing or planned [generating] facility on the generator interconnection customer’s side of the point of interconnection to the RTO/ISO’s transmission system. CAISO basically agreed in concept with this definition. (Straw Proposal, p.28)
This “co-location” definition is more interconnection-related (sharing interconnection facilities before/at the POI) and not necessarily restricted to a single site (or premise – see comments above on that point). For generation/storage resources under the CAISO tariff, that term implies Generating Units in a single Generating Facility sharing a generation tie line and position at a substation. The Generating Units that comprise a single Co-Located Resource (capitalized) arrangement need not be located on a single “site” – they are often spread over vast distances – if they share interconnection arrangements.
Thus, AltaGas does not agree that the term “co-located” has “plain meaning” and thus does not require formal definition. In particular, there is no apparent reason to restrict “co-location” to a single site (or premises) if the LL and resource are sharing the same interconnection facilities.
b. Please provide comments on serving co-located loads.
AltaGas believes that there is tremendous potential to benefit the CAISO system by locating new Large Loads using the same interconnections as existing generation, in at least two ways.
• Using existing interconnections (including substation positions) to serve LLs, allowing for the quicker physical load connection at lower cost. Even smaller commercial loads can have lengthy waits for new service. Large generators already have infrastructure in place that have the capability to connect Large Loads quickly to the grid, as soon as studies can confirm that there would be no adverse impacts on the rest of the system.
• Encouraging LL locating in areas where they will help the grid. Many large Generating Facilities are located in remote areas, with plentiful and economic land that could potentially host LLs. (Such remote areas are becoming common data-center host sites elsewhere in the country.) Many of those areas are also short of deliverability (e.g., SCE Eastern, the only Merchant Zone for Cluster 16 Interconnection Request intake) and/or in the areas of serious deliverability constraints. Siting 50MW or more of load in those areas could help mitigate or relieve those bottlenecks.
Thus, regardless of which tariffs apply to requests by existing generators to add Large Loads, studies of LL additions to existing generator sites should consider benefits that these arrangements offer to both the applicant and the CAISO grid.
- Please provide comments on cost allocation for co-located loads.
As noted above, it is likely that smart LL placement may not result in large transmission needs and may actually reduce the need for new transmission additions
d. Please provide any other comments on this topic.
AltaGas has no comments at this time.
4.
Please provide your organization’s comments on section D. New transmission services for flexible large loads.
a. Please provide comments on the Flexible Interim Load Interconnection (FILI) offering.
b. Please provide comments on the Flexible Load Interconnection – Permanent (FLIP) offering.
c. Please provide any other comments on this topic.
- Please provide comments on the Flexible Interim Load Interconnection (FILI) offering.
AltaGas favors flexible arrangements that allow LLs to interconnection before all upgrades are complete, similar to the Limited Operation Study for resources. However, more work may be needed to determine how and when these loads would be curtailed for different reasons, especially if they are co-located with generation/storage resources.
- Please provide comments on the Flexible Load Interconnection – Permanent (FLIP) offering.c. Please provide any other comments on this topic.
Please see comments above on the FILI offering.
5.
Please provide your organization’s comments on section E. Serving electrically proximate large loads.
Despite FERC guidance, the CAISO does not propose CAISO does not propose to create provisions for interconnection customers to serve electrically proximate LLs, for the reasons listed below. AltaGas provides responses to each.
- CAISO is unaware of any interconnection customer that has elected to use a similar Southwest Power Pool option. This industry is still very new, and that does not mean that some may use it in the future.
- California LL developers have expressed no interest in such an option. Again, planning for these facilities is still very new, and few or none of them have actually been built. It would be hard for LL developers to express interest in options that do not exist.
- Facilitating these interconnections could “complicate and slow more common stand-alone and co-located load and generator interconnections, creating challenges where none existed.” The CAISO offers no evidence or rationale why these kinds of interconnections would adversely
- CAISO is concerned that these interconnections “would potentially implicate California state law, which only contemplates the provision of energy at the same site as the load without becoming an electrical corporation subject to myriad utility requirements.” California law already allows generators to serve loads on up to two immediately adjacent properties without becoming public utilities, so this statement is not accurate.
As noted above, AltaGas believes that the CAISO should at least consider co-location arrangements with LLs on multiple sites/premises as long as the interconnection facilities are shared, similar to the allowances made for multiple Generating Units in a Generating Facility.
6.
Please provide your organization’s comments on the Operational Forecasting Requirements.
AltaGas has no comments at this time.
7.
Please provide your organization’s comments on the proposed Technical Requirements.
AltaGas has no comments at this time.
8.
Please provide your organization’s comments on the Technical Requirements under development.
AltaGas has no comments at this time.
9.
Please provide any additional comments on the straw proposal or Aug 19 meeting discussion.
AltaGas has no comments at this time.
Bay Area Municipal Transmission Group (BAMx)
Submitted 09/02/2026, 04:20 pm
Submitted on behalf of
City of Santa Clara, dba Silicon Valley Power and City of Palo Alto Utilities
1.
Please provide your organization’s comments on section A. Transmission Service to eligible customers.
a. Please provide comments on the definition of large loads.
b. Please provide comments on the large load application process and interconnection study procedures.
c. Please provide comments on the large load operational requirements.
d. Please provide any other comments on this topic
The Bay Area Municipal Transmission Group (BAMx)[1] appreciates the opportunity to comment on the CAISO’s Large Loads Straw Proposal, dated August 12, 2026 (“Straw Proposal”)[2], and the August 19, 2026, stakeholder meeting.
BAMx recognizes the complexity of integrating large loads and co-located generation and appreciates that the Straw Proposal is intended to respond to FERC’s June 18, 2026 Show Cause Order.[3] It remains imperative, however, that the interconnection of large loads in the CAISO follow cost-causation principles, preserve system reliability, and not increase costs for other electricity customers. As BAMx has consistently stated (most recently in its February 25, 2026, comments on the Large Load Considerations Issue Paper[4]), similarly situated loads should receive comparable treatment, and municipal and other non-PTO utilities must have a meaningful role in the study and planning processes that determine the impact of these large loads on the reliability of the grid, and the allocation of costs related to the interconnection of these loads.
a. Definition of Large Loads
BAMx supports establishing a clear definition of “Large Load” but is concerned that the proposed 50 MW single-site threshold leaves two gaps. First, the single-site, 50 MW threshold invites a gaming gap through de-aggregation or staged additions below the threshold. Second, by tying the definition to loads “interconnecting to the CAISO Controlled Grid,” it may create a coverage gap for large loads served at or below 69 kV through a PTO or non-PTO system that nonetheless have equivalent transmission impacts; CAISO should clarify what rules apply to such loads so that similarly situated loads receive comparable treatment.[5]
- Aggregation and look-back. CAISO’s statement that it “has not seen” de-aggregation gaming is not a sufficient or appropriate basis to omit anti-gaming rules; the framework itself creates the incentive to structure below 50 MW.[6] BAMx recommends an aggregation rule for commonly-owned or electrically proximate loads, together with a look-back mechanism for staged additions.
- Internal consistency. Ignoring load concentration is inconsistent with the Straw Proposal’s own technical requirements, which are justified by concentrated-load behavior. BAMx also encourages CAISO to coordinate its technical and operational requirements with NERC's ongoing computational-load work so that a facility subject to both regimes is not exposed to conflicting or duplicative requirements.[7]
b. Application Process and Interconnection Study Procedures
- Make consistency mandatory, not optional. FERC found that PTO tariffs often do not explain study details.[8] BAMx recommends that CAISO require, not merely “encourage” a standardized, transparent study framework with common base cases, assumptions, and criteria across wholesale interconnection studies and PTO retail load-cluster studies (e.g., PG&E Serial/ LC24/LC25/LC26 and the SCE equivalent). BAMx notes that (i) FERC has placed the TO Tariffs directly at issue in this §206 proceeding and may itself direct standardized study provisions,[9],[10] and (ii) CAISO independently possesses authority under the Transmission Control Agreement and its own tariff to condition concurrence, TPP treatment, and TAC cost recovery on studies performed using common base cases, assumptions, and criteria.[11],[12] BAMx urges CAISO to exercise the latter and supports FERC directing the former.
- Mandatory affected-system coordination. CAISO concurrence should require affected-system screening and coordination with non-PTOs before concurrence. For example, Silicon Valley Power’s (SVP) analysis showed that PG&E LC24/Serial loads create reliability (steady-state and short-circuit duty) issues on facilities serving SVP that PG&E’s studies did not identify.[13] Non-PTO reliability and import capability must be protected.
- Cumulative assessment in the TPP — study the right loads. The Straw Proposal would run area-wide cumulative assessment only for CEC-adopted forecast load, relying on individual PTO studies for load-cluster loads. The fast-arriving, concentrated load-cluster requests driving the risk are largely not in the CEC forecast. The PTOs should be required to communicate the aggregate loads expected to progress from the cluster study process and should coordinate with the CEC to develop reasonable forecasts of expected loads and their locations. In the absence of close alignment with the CEC load forecast, BAMx is concerned that the PTO cluster studies will identify the worst case assumptions, not take into consideration loads that won't materialize, and not consider load diversity. That could overstate the need for upgrades. At minimum, BAMx recommends a High/Large-Load sensitivity in the annual CAISO TPP that aggregates active load-cluster requests (e.g., Group 1 and Group 2) above a threshold, so cumulative reliability and congestion effects are assessed before energization rather than merely reported.
c. Large Load Operational Requirements
BAMx supports reasonable, non-discriminatory operational requirements[14] but notes that the Straw Proposal should also resolve the tension between firm operating assumptions (e.g., ride-through) and the curtailability assumed for flexible-load services. BAMx’s detailed comments on operational and technical requirements are provided in Sections 6 and 7 below.
[1] Consisting of the City of Palo Alto Utilities (CPAU) and the City of Santa Clara, dba Silicon Valley Power (SVP)
[2] CAISO, Large Load Considerations Straw Proposal (Aug. 12, 2026) (hereinafter “Straw Proposal”).
[3]California Independent System Operator Corporation, et al., Order Instituting Proceeding Under Section 206 of the Federal Power Act, 195 FERC ¶ 61,214, Docket No. EL26-71-000 (June 18, 2026) (hereinafter “Show Cause Order”).
[4] Located at https://stakeholdercenter.caiso.com/InitiativeDocuments/Comments-BAMx-Large-Loads-Information-Session-Feb-05-2026.pdf
[5]Straw Proposal at 9 (proposing to define a large load as “An End User located at a single site interconnecting to the CAISO Controlled Grid, and that has a peak load of 50 MW or greater”). The Commission’s suggested definition also included a “new commercial or industrial customer” qualifier, a greater-than-69 kV voltage threshold, and a non-co-location prong. See Show Cause Order at p.37.
[6]Straw Proposal at 9 (stating that the CAISO “has not seen developers try to game interconnection processes to avoid MW thresholds through de-aggregation” and “does not believe it is necessary to create additional rules to prevent such gaming on the load side”).
[7] See NERC, Project 2026-02 Computational Loads (initial posting authorized Aug. 19, 2026) (developing foundational Reliability Standards CLO-001-1, CLO-002-1, and CLO-003-1, together with FAC-001-5 and FAC-002-5, for the integration of large computational loads).
[8]See Show Cause Order at P 25 (observing that “[t]he TO Tariffs generally do not explain the details of the study processes or any technical or reliability considerations included in the studies”); see also id. at pp. 48–49 (application process and study procedures).
[9]See Show Cause Order at P 4 (instituting a show cause proceeding under FPA section 206 upon a preliminary finding that “CAISO’s existing Open Access Transmission Tariff (Tariff) and/or the Transmission Owner Tariffs (TO Tariffs) of the Participating Transmission Owners appear to be unjust, unreasonable, or unduly discriminatory or preferential,” and directing both CAISO and the Participating Transmission Owners to show cause or propose tariff revisions); see also id. § II (establishing an FPA section 206(b) refund effective date applicable to the tariffs under investigation).
[10]See Show Cause Order at P 62 (directing that CAISO “and/or the Participating Transmission Owners” cure the lack of “sufficiently clear and consistent provisions” for studying large-load service “or propose Tariff revisions establishing them”); id. PP 34–35 (recognizing that CAISO and/or the PTOs “may elect to address…the issues…by proposing revisions to their tariffs pursuant to their applicable FPA section 205 filing rights,” and requiring any such filing to “explain which of the Commission’s…directives their filing addresses and how it resolves them”).
[11]Straw Proposal at 6 (the CAISO/PTO relationships “are set out in the FERC-approved tariffs of the CAISO and the PTOs and the CAISO transmission control agreement”); see also Show Cause Order at n.9 (identifying the Participating Transmission Owners as signatories to the Transmission Control Agreement); id. at P 24 (a PTO’s transmission revenue requirement components are “under CAISO’s operational control”).
[12]Straw Proposal at 17 (CAISO proposes to “define in its tariff any instances when the CAISO would reject load interconnection study results or decline to consider or approve associated transmission solutions through the TPP”); see Show Cause Order at P 71 (Section 24 of the CAISO Tariff governs the TPP and “inputs required to develop the Transmission Plan, such as the Unified Planning Assumptions and Study Plan”); id. at P 24 (“CAISO collects the Regional Access Charge and then remits the monies…to the Participating Transmission Owners”) (citing CAISO Tariff § 26.1).
[13] See the CAISO Decision on Updates to the ISO 2025-2026 Transmission Plan - Memo - Aug 2026 located at https://www.caiso.com/documents/decision-on-updates-to-the-iso-2025-2026-transmission-plan-memo-aug-2026.pdf
[14]See Show Cause Order P 63 (enumerating operational requirements, including hourly forecasts, telemetry, ride-through, ramp-rate, and remote-disconnect capability); Straw Proposal at 17–21.
2.
Please provide your organization’s comments on section B. Framework to prevent cost-shifting.
a. Please provide comments on roles and responsibilities to prevent cost shifting.
b. Please provide comments on data transparency.
c. Please provide any other comments on this topic.
a. Roles and Responsibilities to Prevent Cost-Shifting
BAMx does not agree with the conclusion that no cost-allocation change is necessary at this time. The Straw Proposal acknowledges the cross-PTO cost-shift — a PTO’s large-load-driven upgrade costs enter its Transmission Revenue Requirement (TRR) and then the single regional Transmission Access Charge (TAC), but reasons that upfront developer payments offset rate base, so no change is needed.
Longer reimbursement period to preserve “skin in the game.” Under existing practice, upfront payments for network upgrades are reimbursed to the funding customer over approximately five years through the PTO’s TRR, which flows into the TAC. The upgrades are therefore ultimately TAC-funded. An upfront payment that is reimbursed through the TRR is interim financing; reimbursement is appropriate, but a five-year horizon repays the causing customer well before the durability of its load is demonstrated. To mitigate the resulting stranded-cost and durability risk, BAMx recommends that large loads be permitted to recover their upfront-funded network-upgrade costs over a period substantially longer than the current approximately five-year generator reimbursement period (the specific length subject to further evaluation and confirmation).[1] A longer reimbursement horizon keeps the customer that caused the need for the costs to be incurred financially committed across more of the upgrade’s early life and better aligns cost recovery with the durability of the load it serves.
The mismatch between asset life and load life is stark. A transmission upgrade is a long-lived asset whose revenue requirement is recovered over decades, but the data center load it serves is neither necessarily long-lived nor site-bound. The AI accelerators that drive these loads have a useful life of only up to three years under high-utilization workloads, forcing continuous hardware refresh and giving operators repeated occasions to re-evaluate whether a site remains economic.[2] Because computing workloads can be shifted or migrated geographically in response to power prices, interconnection costs, or other economics, an operator that finds a cheaper location has both the ability and the incentive to relocate or downsize — and a growing share of new capacity is being designed to bypass or partially defect from the utility grid entirely.[3] A five-year reimbursement window is therefore roughly one-to-two hardware cycles long: by the time the causing customer’s upfront funding is fully repaid, the load that justified a multi-decade transmission investment may have moved on, leaving the remaining ratepayers to carry a stranded, underutilized asset. Aligning the reimbursement period with the durability demonstrated by the load — rather than a generator-derived five-year default — is the most direct way to keep cost recovery matched to cost causation.
This concern extends beyond loads that disappear entirely. Transmission upgrades are planned and sized based on projected load growth, yet actual demand may fall significantly short of those projections. For example, a network upgrade may be justified by a projected 500 MW large load, while actual demand ultimately reaches only 100 MW. Had the lower demand level been reflected in the original planning assumptions, the upgrade may not have been required, may have been deferred, or may have been replaced with a less costly alternative. Although the load has technically materialized, the realized demand may be insufficient to justify the transmission investment approved based on the original forecast. As a result, the transmission facility may become substantially underutilized, creating many of the same cost-shifting concerns as a project that fails to materialize altogether.
If a data center closes or downsizes after five years, once its upfront funding has been fully reimbursed — the TRR associated with the long-lived transmission upgrades remains (a persistently high numerator), while the billable load that upgrade was built to serve disappears (a shrinking denominator). The TAC rate then rises for everyone else, and the remaining ratepayers are left paying for excessive and underutilized transmission upgrades.[4] Extending the reimbursement period ensures these projects retain “skin in the game” and reduces this cost-shift exposure for other customers.
- Direct assignment / permanent contribution. CAISO should require direct cost assignment to the causing load, or a permanent (non-reimbursed) contribution, for large-load-driven upgrades that do not provide demonstrable net system benefits. In addition, CAISO should consider forecast-accountability mechanisms for situations where actual load materially underperforms the forecast used to justify transmission upgrades. Such mechanisms would help ensure that existing transmission customers are not exposed to the costs of stranded or underutilized facilities resulting from substantial load forecast shortfalls.
- Restart 2018 TAC reform. CAISO should restart the 2018 TAC Structure Enhancements to move from a purely volumetric charge toward demand-based cost recovery that better reflects peak-driven cost causation. See BAMx’s February 25, 2026, comments on the Large Load Considerations Issue Paper for further details.[5]
b. Data Transparency
BAMx supports increased transparency[6] but notes that posting aggregate load additions and cost estimates is not a substitute for a system-wide reliability and congestion assessment. BAMx requests regular, granular disclosure sufficient for stakeholders to evaluate cost exposure, including which upgrades are customer-financed versus TAC-recovered; the aggregate cost and the TAC-recovered portion for each; and the cumulative interconnection impacts across PTOs.
[1]Under the CAISO’s interconnection framework, network-upgrade contributions are generally reimbursed to the funding party over approximately five years through the PTO’s TRR. See also Show Cause Order P 82 (recognizing “potential timing differences between when costs are incurred to develop needed Network Upgrades and the pace at which the large load ramps toward energizing at its full level of requested service”).
[2]Multiple industry sources place the useful life of high-utilization AI/data-center GPUs at roughly one to three years. See Anton Shilov, Datacenter GPU service life can be surprisingly short — only one to three years is expected according to unnamed Google architect, Tom’s Hardware (Oct. 24, 2024) (reporting that, at 60–70% utilization, a datacenter GPU “will typically survive between one and two years, three years at the most”); see also Junde Liu, Hardware Lifecycle, Warranty, and Retirement for AI Data Centers (Aug. 3, 2026) (AI GPU clusters’ “physical useful life under a heavy training workload is often only one to two years, with three years as a maximum”); STS Electronic Recycling, 2026 AI Data Center ITAD Trends (May 2026) (AI GPU servers “cycling through enterprise data centers within 2 to 3 years”). BAMx notes that estimates vary and that some analysts contend GPUs remain useful longer by shifting from training to inference roles; the point here is not that the silicon fails at year three, but that operators face a refresh or relocation decision on a multi-year cycle far shorter than the life of the transmission asset.
[3]See Aron Brenner, Line Roald & Saurabh Amin, Strategic Data Center Load Shifting: Implications for Market Efficiency and Transmission Value (MIT/UW-Madison, Nov. 2025) (large operators “can migrate workloads” and act as “sources of spatial and temporal flexibility,” and by repositioning can “eliminate the marginal value of transmission expansion”); Data Centers Going Off-Grid Threaten Utility Revenue Models, Developments Today (Mar. 18, 2026) (“Grid defection creates stranded cost risks as utilities built infrastructure for loads that may not materialize on the grid”).
[4]See Show Cause Order at PP 55, 78 and 82 (expressing concern that speculative requests, or loads that operate “at a lower demand than anticipated or fail [] to materialize at all,” could shift stranded network-upgrade costs onto other transmission customers “which may result in those costs then being passed through to residential customers”).
[5] Located at https://stakeholdercenter.caiso.com/InitiativeDocuments/Comments-BAMx-Large-Loads-Information-Session-Feb-05-2026.pdf
[6]See Show Cause Order at PP 70–75 (additional cost transparency directives); Straw Proposal at pp. 26–28 (proposing to publicly post aggregate large-load additions, planned network upgrades, and cost estimates).
3.
Please provide your organization’s comments on section C. Requirements for co-located arrangements.
a. Please provide comments on terminology.
b. Please provide comments on serving co-located loads.
c. Please provide comments on cost allocation for co-located loads.
d. Please provide any other comments on this topic.
No comments on this topic at this time
4.
Please provide your organization’s comments on section D. New transmission services for flexible large loads.
a. Please provide comments on the Flexible Interim Load Interconnection (FILI) offering.
b. Please provide comments on the Flexible Load Interconnection – Permanent (FLIP) offering.
c. Please provide any other comments on this topic.
a. Flexible Interim Load Interconnection (FILI)
BAMx supports flexible service options in principle.[1] To protect firm customers, including municipal firm load, CAISO should require enforceable and verifiable curtailment obligations, with transparent treatment of that curtailment in planning studies. FILI should be capped and time-limited so that interim service does not become a permanent substitute for needed transmission upgrades.
b. Flexible Load Interconnection — Permanent (FLIP)
- Support with guardrails. BAMx supports pursuing FLIP, subject to enforceable curtailment and firm-customer protection.[2]
- Address the “flip-to-firm” risk. If a FILI or FLIP load later requests firm service, cost responsibility for the previously deferred upgrades should attach to that load at that point. This is particularly important because CAISO reports that developers to date have expressed interest only in firm service and would accept flexibility only temporarily, so the durability of a permanent flexible construct is untested.[3]
c. Other Comments on This Topic
The Straw Proposal should resolve the firm-versus-flexible modeling tension: ride-through and other technical requirements assume firm behavior, while FILI/FLIP assume curtailability. CAISO should clarify which assumption governs planning studies for a given load.
Additionally, CAISO should clarify the minimum transmission capability and reliability criteria that must exist at a proposed point of interconnection before FILI or FLIP service can be offered. While the flexibility concepts are intended to facilitate faster and more economical interconnections, stakeholders would benefit from transparency regarding how CAISO and PTOs will determine whether a location is suitable for flexible service and whether there are circumstances where transmission limitations are too significant to be addressed through operating restrictions alone. Clear eligibility criteria would help ensure consistent application of FILI and FLIP across projects while maintaining reliable system operations.
[1]Straw Proposal at pp. 37–38 (describing FILI and FLIP as new interconnection — not transmission — service options).
[2]See Show Cause Order § III.D (directing CAISO to explain whether its Tariff remains just and reasonable without (1) an interim non-firm network transmission service while upgrades are constructed and (2) permanent firm and non-firm contract-demand transmission services, or to propose such revisions).
[3]Straw Proposal at 38 (“To date, no stakeholder has requested that the CAISO develop non-firm transmission services. To the contrary, developers consistently express that they are only interested in acquiring firm service and would only agree to be flexible temporarily to interconnect before completion of long-lead network upgrades.”).
5.
Please provide your organization’s comments on section E. Serving electrically proximate large loads.
No comments on this topic at this time
6.
Please provide your organization’s comments on the Operational Forecasting Requirements.
Reconcile firm and flexible service constructs in the forecasting framework. A large load’s assumed operating envelope drives both the day-ahead and real-time schedules its load-serving entity’s Scheduling Coordinator submits and the assumptions CAISO and the PTOs use to plan for it; static data flow from the PTOs and dispatch-level data from the LSE scheduling coordinator.[1] A single load cannot coherently be modeled as firm for planning while being dispatched as flexible in operations, or the reverse. The forecasting framework must therefore make the operating envelope assumed in the forecast consistent with the service the load actually takes (firm, FILI, or FLIP), so that CAISO neither over-builds for flexibility it will not receive nor under-builds against firm withdrawals it does not expect.
- Define the governing operating envelope by service type. CAISO should identify, for each service (firm, FILI, and FLIP), the operating envelope — e.g., contract-demand or firm level, curtailable quantity, curtailment priority among load blocks, response time requirements and the conditions that trigger curtailment — that the LSE’s scheduling coordinator must reflect in its day-ahead and real-time schedules, so the CAISO markets and available operator actions are appropriately modeled in both the Day-Ahead and Real-Time markets and can be acted upon depending on the service in effect.
- Tie the forecast to planning assumptions. The withdrawal profile assumed in operational forecasting should be consistent with the load-coincidence and firm operating-envelope assumptions used in the TPP and in interconnection studies. If transmission planning credits a load with curtailment (FILI/FLIP) but the forecast and operations treat it as firm, needed upgrades may be deferred — exposing CAISO ratepayers to reliability risk and, potentially, to market costs they did not cause.
- Re-verify when service changes. Because a FILI load transitions to firm upon completion of its network upgrades, and a FLIP load may later seek firm service, the forecasting obligation should require re-submission of the operating envelope whenever the service level changes, together with verification that actual withdrawals conform to the flexibility the planning assumptions credited.
[1]Straw Proposal at 21 and fn.31 (“Static information about the large loads will come from the PTOs…Day-ahead and real-time information will come from the load-serving entity scheduling coordinator responsible for the large load’s demand”; the large load’s demand “would be scheduled by their load-serving entity”).
7.
Please provide your organization’s comments on the proposed Technical Requirements.
BAMx generally supports reasonable, technology-neutral technical requirements (e.g., ride-through, Post-Fault Active Power Recovery (PFAPR), ramp-rate, Phasor Measurement Unit (PMU)/telemetry, Electromagnetic Transient (EMT) modeling, and commissioning) but recommends that the compliance costs of these requirements be allocated to the causing large load.[1]
[1]Straw Proposal at pp. 20–21 (noting that the Large Load Technical Requirements Straw Proposal “does not specify cost allocation” for PMUs and “does not establish hourly forecasting requirements”); cf. Show Cause Order at P 63 (PMU costs “assigned to the transmission customer”).
8.
Please provide your organization’s comments on the Technical Requirements under development.
Several technical items remain “TBD.”[1] BAMx requests that the CAISO provide a meaningful opportunity for stakeholders to review and comment on these items once developed and recommends that they be applied consistently across all PTOs to ensure comparable treatment.
[1] See CAISO, Large Load Technical Requirements Straw Proposal (June 15, 2026) at pp. 22–34.
9.
Please provide any additional comments on the straw proposal or Aug 19 meeting discussion.
- Non-PTO inclusion. Require explicit recognition and participation rights for non-PTO utilities, and mandatory affected-system coordination before CAISO concurrence.
- Process fairness. Given the compressed schedule to an October 28 Board decision, including only a single round of comments on the straw-proposal, CAISO should commit to providing an additional opportunity for stakeholder comments if the draft final proposal is materially changed from the straw proposal.[1]
BAMx appreciates the CAISO’s consideration of these comments and looks forward to continued engagement as the initiative proceeds.
[1]Straw Proposal at p. 40 (Initiative Timeline and Next Steps).
California Department of Water Resources
Submitted 09/02/2026, 03:42 pm
1.
Please provide your organization’s comments on section A. Transmission Service to eligible customers.
a. Please provide comments on the definition of large loads.
b. Please provide comments on the large load application process and interconnection study procedures.
c. Please provide comments on the large load operational requirements.
d. Please provide any other comments on this topic
The California Department of Water Resources – State Water Project (CDWR-SWP) thanks the California Independent System Operator (CAISO) for the opportunity to comment on the CAISO’s Large Load Straw Proposal. CDWR-SWP generally supports CAISO’s efforts to meet FERC’s Section 206 Show Cause Order of June 18, 2026. Cal. Indep. Syst. Operator Corp., 195 FERC ¶ 61,214 (2026) (Show Cause Order).
Background:
- Since the 1960’s, the CDWR-SWP has worked to reliably store and deliver water to what is now 27 million Californians, 750,000 acres of farmland, and businesses throughout California each year. The series of canals, pipelines, reservoirs and hydroelectric power facilities along the California aqueduct stretch from Northern California to Southern California. The pumps that feed the SWP together historically make up 2-3% of CAISO’s annual gross load. These pumps are primarily interconnected to the transmission system through a small network of CDWR-SWP owned facilities and tie lines.
a. Please provide comments on the definition of large loads.
The CDWR-SWP supports CAISO waiting to align the large load definition with NERC’s definitions for computational load. The CDWR-SWP's understanding is that CAISO is proposing to apply the definition to new large loads and not to existing loads. When a new definition is adopted, CDWR-SWP recommends CAISO specifically stating in the tariff language that the definition applies only to new large load interconnections. Doing so would be consistent with the potential definition suggested by FERC’s Show Cause Order Show Cause Order P 1 n.2 .
b. Please provide comments on the large load application process and interconnection study procedures.
The CDWR-SWP understands that the FERC Show Cause Order is directed jointly at the CAISO and PTOs. As noted by the CAISO, the load application and interconnection processes are proposed to remain largely unchanged from the CAISO’s standpoint. The CAISO further expects the PTOs to coordinate amongst each other to align study processes with one another as well as with the CAISO’s study processes for studying co-located load interconnections. CDWR-SWP asks that CAISO and the PTOs share the PTOs’ proposals with stakeholders before their tariff revisions are filed at FERC. CDWR-SWP is particularly interested in any Affected Systems processes that are developed for load interconnections as well as seeking more clarity on the co-located load interconnection process being developed by the PTOs in consultation with CAISO. CDWR-SWP remains concerned about the potential impacts new computational loads can have, especially on CDWR-SWP’s large pumping plants which consist of synchronous large rotating mass. CDWR-SWP believes that sharing the PTO proposals with stakeholders before filing is mutually beneficial for all parties as it will allow stakeholder concerns to be addressed collaboratively before filing to the extent possible. CDWR-SWP strongly urges CAISO to include the PTOs in the stakeholder process to enable stakeholders the opportunity to have some input into the PTOs process prior to the FERC filing deadline.
c. Please provide comments on the large load operational requirements.
d. Please provide any other comments on this topic
2.
Please provide your organization’s comments on section B. Framework to prevent cost-shifting.
a. Please provide comments on roles and responsibilities to prevent cost shifting.
b. Please provide comments on data transparency.
c. Please provide any other comments on this topic.
a. Please provide comments on roles and responsibilities to prevent cost shifting.
The CDWR-SWP is supportive of CAISO efforts to ensure new large loads bear equitable responsibility for costs incurred from their interconnection to and use of the transmission system. CDWR-SWP understands that the PTOs will be in charge of developing and executing pro forma cost recovery agreements. CDWR-SWP believes that CAISO should still be a party to these agreements, especially if the agreements lead to increases in Transmission Access Charges (TAC). Indeed, FERC’s Show Cause Order contemplates cost recovery agreements “between CAISO, the relevant transmission owner, and the Eligible Customers taking transmission service on behalf of large loads.” CDWR-SWP remains concerned that cost shifting may still occur if new large load related network upgrades are rolled into the PTO’s Transmission Revenue Requirement (TRR) and ultimately TAC, making CAISO’s involvement in the primary mechanism to prevent cost shifting (i.e., the cost recovery agreements) critical. The public posting of the outcomes of these agreements is paramount for transparency and for accounting purposes. CDWR-SWP also encourages CAISO to include any alternatives that were considered especially for TPP projects.
Finally, given that preventing cost-shifting is one of the most important issues raised in the Show Cause Order, CDWR-SWP reiterates that it would be beneficial to all parties if the CAISO and PTOs share the PTOs’ cost recovery agreement proposals with stakeholders before they are filed at FERC.
b. Please provide comments on data transparency.
The CDWR-SWP remains concerned that the current framework with much of the onus being on the PTOs is not sufficiently transparent. CDWR-SWP strongly urges CAISO to include the PTOs in the stakeholder process to enable stakeholders the opportunity to have some input into the PTOs process prior to the FERC filing deadline. CDWR-SWP would additionally like more clarity on the processes CAISO assigned to PTO tariff revisions including transparency on network upgrade costs triggered by large loads. CDWR-SWP requests clarity with respect to FERC’s proposal on simultaneously studying the interconnection of co-located large loads with on-site generation to potentially achieve savings in network upgrade costs. The PTOs proposals are not transparent since they are not publicly available and stakeholders should have opportunity to review both the CAISO and PTOs proposals as a whole as intended by FERC’s Show Cause Order.
c. Please provide any other comments on this topic.
The straw proposal is inconsistent about whether large loads are retail or wholesale customers. Some parts treat them as retail load, scheduled by load-serving entities (footnotes 31, Section C.2; footnote 34). Other parts tie them to wholesale mechanisms, like the CAISO Controlled Grid interconnection (section A.1.), network upgrades and TAC (Section B; C.3.b) and ancillary service charges (Section C.3.a). CDWR-SWP asks CAISO to clarify how large loads can be both, and to fix the inconsistency in future proposals.
Footnote 34 also says a Participating Load Agreement isn’t required because it applies only to wholesale services, “which are not relevant to this initiative at this time,” CDWR-SWP asks the CAISO what “at this time” means, and what would change that later.
This clarification matters directly to CDWR-SWP. CDWR-SWP already has a Participating Load Agreement for SWP pumping load, which is a wholesale agreement. CDWR-SWP is not suggesting that CAISO look to the PLA as a model for the new large interconnection requirement in this initiative. CAISO's proposed FILI and FLIP offerings suggest CAISO already agrees that rather than modifying or extending the PLA, CAISO created new interconnection service products for large load flexibility. This might be CAISO’s answer to why PLAs are “not relevant to this initiative at this time,” and CDWR-SWP asks CAISO to confirm that this is the intended meaning, that the PLA and large load framework are meant to function as separate, parallel mechanisms. Participating Load, including real-time load bidding, is being developed separately through CAISO's DDEMI Track 2 and the pumping load working group. CDWR-SWP asks CAISO to ensure that the Large Loads initiative does not create unintended impacts on the DDEMI effort. CDWR-SWP raises the question about the PLA only because, at wholesale, it currently appears to be the only existing vehicle providing flexibility for large loads, which is part of why the retail versus wholesale ambiguity necessitates clarification.
3.
Please provide your organization’s comments on section C. Requirements for co-located arrangements.
a. Please provide comments on terminology.
b. Please provide comments on serving co-located loads.
c. Please provide comments on cost allocation for co-located loads.
d. Please provide any other comments on this topic.
a. Please provide comments on terminology.
b. Please provide comments on serving co-located loads.
c. Please provide comments on cost allocation for co-located loads.
CAISO is not proposing to change the current constructs for BTM generation, Gross Load, and TAC, but CAISO does not clearly address how the netting of BTMG against load for purposes of TAC assessment interacts with how co-located loads would be studied and assessed costs for interconnection service.
CAISO’s proposal does not clearly address how load with co-located generation would be treated when the generation is unavailable. For example, if a new, 100 MW co-located large load applies for 20 MW of interconnection service because it has 80 MW of co-located generation, what mechanisms will be in place to ensure the Load Interconnection Customer does not take service for the full load? Allowing the new co-located large load to take service for the full 100 MW of load while only being studied for 20 MW of load will allow it to reduce its exposure to directly-assigned reliability network upgrades, decrease system reliability, and shift costs to other customers. The straw proposal does not explain whether, and, if so, how, these necessary safeguards would be addressed in arrangements for firm, Flexible Interim Load Interconnection (FILI), or Flexible Load Interconnection – Permanent (FLIP). If a co-located new large load would like to have its full load served if its co-located load generation is unavailable, CAISO should have mechanisms in place to ensure that the full load has been studied and assessed costs consistent with such operations. To ensure that these mechanisms are working properly, there must be transparency on what transmission services are requested by these co-located loads.
d. Please provide any other comments on this topic.
4.
Please provide your organization’s comments on section D. New transmission services for flexible large loads.
a. Please provide comments on the Flexible Interim Load Interconnection (FILI) offering.
b. Please provide comments on the Flexible Load Interconnection – Permanent (FLIP) offering.
c. Please provide any other comments on this topic.
5.
Please provide your organization’s comments on section E. Serving electrically proximate large loads.
6.
Please provide your organization’s comments on the Operational Forecasting Requirements.
Section A.4 identifies “hourly forecasts, telemetry, and other operational data” as one of four operational requirements from the Commission’s Order that is not fully addressed by the Large Loads Technical Requirements Straw Proposal, which CAISO proposes to adopt here. At the workshop, CAISO explained: its forecasting methodology is built for conforming load, ordinary demand that follows predictable weather patterns and time patterns. Large Loads are non-confirming, which creates data gaps and risks systematically low-biased forecasts (understanding demand) as large load growth outpaces the historical data these models are trained on. CAISO proposes addressing this by extending methods it already uses for non-conforming resources like demands response and large battery schedules. CDWR-SWP supports this effort.
CDWR-SWP wants to highlight a related functionality gap as a priority. Participating Load has Day-Ahead scheduling functionality today, but there is no real-time adjustment. This is being explored in the DDEMI effort. CDWR-SWP asks CAISO to prioritize this functionality since this affects whether the real-time forecast updates proposed here can be delivered.
CDWR-SWP understands that CAISO plans to address gaps in the operational requirements that have not fully been addressed by the Large Loads Technical Requirements Straw Proposal. CAISO defines adoption of four requirements to address forecasting gaps within the document. For "Hourly forecast, telemetry, and other operational data to provide the CAISO sufficient operational visibility", Can CAISO provide detailed specifications for the new data requirements for Large Load Resources? What level of forecasting will be required to be provided by Large Load Resources to address the gaps that CAISO have identified for sufficient operational visibility? And, consistent with CDWR-SWP's comments in Section 1.a, will these operational requirements apply to existing load resources, or only to new large load interconnections?
7.
Please provide your organization’s comments on the proposed Technical Requirements.
8.
Please provide your organization’s comments on the Technical Requirements under development.
The CAISO has mentioned that EMT studies will only be performed in select circumstances. CDWR-SWP encourages CAISO to require EMT studies for all projects. CDWR-SWP remains concerned about the potential impacts new computational loads can have, especially on CDWR-SWP’s large pumping plants which consist of synchronous large rotating mass. Additionally, what guarantees are in place that once a load interconnection is approved that the load will not substantially change its operation and load characteristics as studied? Large data centers could be comprised of many different off-takers with varying scheduling needs, software or hardware updates can change the demand profile, etc. Are these considerations being taken into account in the modeling of these load applications?
9.
Please provide any additional comments on the straw proposal or Aug 19 meeting discussion.
FERC’s Show Cause Order underscores that the influx of large loads heightens the need to ensure just, reasonable, and not unduly discriminatory rates. As these new large loads drive transmission cost increases, they exacerbate concerns with rates that fail to properly assess costs commensurate with the causes of those costs. CDWR-SWP realizes that the TAC is currently assessed on a volumetric basis, but CAISO has previously proposed a Hybrid TAC model based on Peak Demand and Volumetric use.
CAISO should consider the Hybrid TAC model in this proceeding as it could better address FERC’s concerns with cost causation and cost shifting while decreasing the need for costly network upgrades that may not be needed to support the transmission system. FERC recognized in the Show Cause Order (P 125) that “there may be a variety of possible approaches to protect customers from significant cost shifts associated with network upgrades triggered by large loads.” Particularly given that the Straw Proposal leaves the issue of cost recovery agreements entirely to the PTOs (with stakeholders having no indication of whether the PTOs will actually pursue that approach, or what those agreements might look like), CAISO should not ignore the improvements it can make with respect to items within its historical responsibility—i.e., the TAC assessment methodology.
The hybrid TAC model combines volumetric and peak demand-based billing to provide better cost containment incentives to large load, capitalizing on the benefits of both approaches while avoiding the shortcomings of exclusively relying on just one. As described by CAISO, volumetric billing does not allow large load with BTMG to “mask” its transmission usage by utilizing its BTMG during the peak period. Straw Proposal at P 36. Further, volumetric billing assesses charges based on actual use of the transmission system, which does not incentivize load to use the system efficiently. But volumetric billing does not help reduce the transmission infrastructure needed to serve large load as it does not incentivize efficient use of the system and as such does not account for peak demand, which is an important component in sizing and determining network upgrades for the transmission system. The concept of Gross Load as currently defined would coexist in a hybrid TAC structure, which would continue to have a volumetric component (and thus remain fundamentally different than PJM’s transmission charges). As diverse and new types of large loads seek to interconnect to the transmission system, a TAC methodology that more comprehensively reflects the value of different uses and benefits of the system (i.e., both volumetric and peak demand approaches) will better prevent inappropriate cost-shifting.
The hybrid TAC methodology will also address FERC’s concern that flexible large load is being insufficiently addressed by CAISO’s current transmission service offerings. In addition to FILI and FLIP, CAISO should consider adopting the Hybrid TAC model because the demand component of hybrid TAC would incentivize flexible large load “to limit their use of the transmission system under certain conditions” which “can avoid inefficient and costly transmission system build-out.” Show Cause Order P 104. Promoting load flexibility through hybrid TAC would reduce peak demand and increase system reliability, thereby reducing network congestion as well as the underlying need for network upgrades. As noted in the Show Cause Order, “commenters observe that flexible large loads can quickly and verifiably adjust their consumption in response to system conditions or price signals,” and FERC directed the CAISO to account for this flexibility in its response. (Show Cause Order PP 103, 104.) Adding a temporal element to the TAC model will help ensure that the appropriate price signals are sent.
CDWR-SWP continues to advocate for a Hybrid TAC model and hopes CAISO considers these impacts in this initiative.
California Public Utilities Commission (CPUC)
Submitted 09/02/2026, 02:22 pm
Submitted on behalf of
California Public Utilities Commission (CPUC)
1.
Please provide your organization’s comments on section A. Transmission Service to eligible customers.
a. Please provide comments on the definition of large loads.
b. Please provide comments on the large load application process and interconnection study procedures.
c. Please provide comments on the large load operational requirements.
d. Please provide any other comments on this topic
a.)
In its Large Loads Considerations Straw Proposal (Straw Proposal) CAISO acknowledges FERC’s presumption that a large load is greater than 50 MW at a single site on its grid, but seems to prefer excluding a voltage threshold and customer class from its definition. Instead, CAISO seems to focus more on system-level reliability, planning, and operations. CPUC staff concur with CAISO that it is appropriate to allow other processes, such as NERC’s, to propose a definition prior to CAISO defining large loads.
Note that the term “large load” implies a peak demand and not necessarily anything else per se, for instance such as an interconnecting voltage level at which the large load is served (although most would be better served at higher, transmission voltages). Well-established engineering design practices can be employed to optimize the design and service voltage level, and CPUC staff agree with CAISO that the definition of large loads should not include descriptions of the types of load.
b)
CPUC staff acknowledge the existing load interconnection processes currently under the domain of the individual Participating Transmission Owners (PTO). However, PTO processes related to large load scale and size, at the projected quantity of projects, have not been tested. The participation of all relevant agencies located in the state of California with the appropriate knowledge, skills, and abilities will be required to maintain safety and reliability at the lowest possible cost.
Please note that the need for EMT study data is also being evaluated in other forums such as IEEE 1547.7 and NERC. State entities will need to formulate how these data will be collected and stored to ensure their consistent availability at a central, known location when required. It would make sense for CAISO to take a lead role in preparing and maintaining the state’s EMT data.
While the OSC appears to hold the CAISO and relevant PTOs jointly accountable for addressing the identified tariff issues, the Straw Proposal relies on the PTOs to develop consistent application processes, study requirements, and timelines without any updates to its own tariff to reinforce these requirements. As such, the Straw Proposal lacks any enforcement details pertaining to these requirements. CAISO’s proposal appears to rely on the PTOs to deter speculative requests without concrete accountability measures, which risks perpetuating the problem.
Additionally, CAISO’s proposal expects that the PTOs will complete studies within 60-90 days in order to align with CAISO processes to inform CAISO’s broader transmission planning, resource interconnection, and deliverability allocation procedures. However, this timeline process could be challenging for PTOs to realize due to the anticipated large volumes of large load interconnection requests.
The Straw Proposal indicates that, since it has not yet “seen developers try to game interconnection processes to avoid MW thresholds through de-aggregation,” (Straw Proposal, p. 9) the CAISO “does not believe it is necessary to create additional rules to prevent such gaming.” (Straw Proposal, p. 9) Electing to wait until CAISO sees evidence of customers “gaming the system” before it initiates the process to prevent such practices presents a risk that could lead to significant costs to ratepayers. A more proactive approach would be for CAISO to enact rules that are clear and consistent, to both anticipate and prevent such gaming from occurring in the first place.
c.)
CPUC staff support CAISO’s proposal that envisions comprehensive coordination (i.e., via the LLTRWG) with utilities, regulators, NERC, and WECC. CAISO proposes PTOs provide large load interconnection information to load serving entities, including expected hourly flexibility capability. CPUC staff commend this transparency, and further proposes PTOs also require large loads to provide information regarding what, if any, mandatory or optional demand flexibility rates/tariffs or demand response program(s) each flexible large load plans to participate in, including relevant details.
d.)
N/A
2.
Please provide your organization’s comments on section B. Framework to prevent cost-shifting.
a. Please provide comments on roles and responsibilities to prevent cost shifting.
b. Please provide comments on data transparency.
c. Please provide any other comments on this topic.
a)
A defining feature of CAISO’s Straw Proposal is its deference to PTOs to address the cost shifting issues emphasized in FERC’s Order. This raises a number of questions, several of which are described here:
It makes sense that CAISO wants to avoid “top-down” cost approaches, but there is a risk of a far greater top-down imposition by FERC if the CAISO and PTOs fail to jointly address these matters in their November filing(s). CPUC is eager to better understand how the ISO and PTOs will satisfy what appears to be FERC’s imposition of joint responsibility for meeting these requirements and is hopeful that CAISO and PTOs will present their unified vision in the Draft Final Proposal and the Stakeholder workshop on September 28th to assure stakeholders the required alignment is occurring in the clear and consistent manner ordered by FERC.
CAISO notes that it is considering being party to tripartite agreements with large load customers and PTOs, similar to the large generator interconnection agreements, and the CPUC is hopeful that CAISO will pursue this approach. FERC seems to acknowledge that loads in excess of 50 MW pose enough risk to the grid and ratepayers that these matters need to be addressed by both the ISO and PTOs. Therefore, it is a reasonable expectation that CAISO would be a signatory.
-
Jurisdiction. CPUC authority to enact policy with respect to costs reflects limits imposed by the Federal Power Act (“FPA”), which delineates what falls under federal jurisdiction. FERC jurisdictional cost allocation and cost recovery is not within CPUC’s regulatory authority. Thus, to the extent that the CAISO and PTO responses to the FERC Order intend to address FERC’s concerns regarding cost shifts with cost causation-based policies, it is important that this policy be implemented upstream of the retail rate cost recovery / allocation stage – at the FERC jurisdictional level.
-
Wholesale Cost Shifts. No new processes were outlined in the Straw Proposal to prevent cost shifting between CPUC-regulated and other utilities. Retail rate design cannot address the issue of wholesale cost shifts, which are upstream of the retail design process. The CPUC is concerned that absent clear upstream mechanisms that appropriately allocate costs to large load customers, ratepayers of one PTO will pay for assets that serve large load customers of another.
-
Incentives. The CPUC is concerned that assigning responsibility for ratepayer protections to the PTOs presents a misalignment of incentives. PTOs earn a rate of return on assets in ratebase and earn more if the cost of assets in ratebase is greater. Cost controls in FERC jurisdictional investments are meager, and state regulators are jurisdictionally constrained in imposing the required cost discipline. As a foundational matter, it is unclear why, absent meaningful cost constraints, a PTO would seek to establish or enforce effective FERC jurisdictional cost protections for ratepayers. There is a place for cost controls upstream of retail rate design, and the CPUC recommends that the collective CAISO / PTO responses include caps or other mechanisms to support FERC’s mandated ratepayer protections such as credit and minimum contribution requirements.
-
Credit and Minimum Contribution Requirements. Retail rate design cannot address the credit requirements or minimum contribution requirements, associated with FERC jurisdictional asset costs, which FERC has identified in the Order as requiring changes. The CAISO proposal appears to defer to PTOs on these requirements. The CPUC recommends that CAISO and PTOs take measures to ensure that cost estimates are accurate, that credit and minimum contributions align accurately with the costs to be incurred to serve large loads, lest the risk of load failing to materialize outpace ratepayer protections.
-
Consistency in implementation. FERC’s Order points to “clarity and consistency” to describe its requirements for a just and reasonable tariff. While the CAISO cannot enforce requirements on the PTOs, an upstream CAISO tariff solution establishing certain minimum requirements for determining allocation of costs based on principles of causation achieves the same result without requiring such wrangling. In referencing the Southwest Power Pool tariff example in its Order, FERC throws a lifeline to the named respondents, highlighting a tariff regime the mechanics of which minimize coordination overhead by allowing upstream changes to simply flow down uniformly to PTOs via the CAISO tariff. CPUC encourages CAISO to consider this approach.
b.)
The FERC Order states, “We preliminarily find that cost transparency measures are needed to provide stakeholders with sufficient information and visibility regarding the network upgrades, and their associated costs, needed to accommodate transmission service to Eligible Customers on behalf of large loads.” (FERC OSC, p. 29) Specifically, FERC requires CAISO to post to its website, in a manner searchable by large load and TNU, the cost causation of each TNU attributable to demand from each large load, 50 MW and above. This cost matrix is the critical input to cost allocation / assignment, credit and minimum contribution requirements, and other ratepayer protections, as well as to regulatory processes reliant on accurate load projections.
CAISO’s Straw Proposal appears to default to per unit cost guides, which have been unreliable, and suggests its intention to provide only aggregated transmission upgrade costs. The CPUC believes that FERC is calling for greater transparency of costs and cost causation related to specific network upgrades triggered by large load customers. Satisfying this requirement is critical to effective implementation of downstream requirements of the Order, including causation-based cost allocation.
CAISO’s proposal speaks to so-called concurrence projects that CAISO does not approve but acknowledges will not negatively impact reliability of the grid in its Transmission Plans. TOs have sought recovery of these load-specific costs in TO rates as though the costs support general grid benefits serving all ratepayers. The inclusion of these projects in the 2025-26 Transmission Plan demonstrates the transparency that is possible with respect to upgrades clearly triggered by specific large load interconnections, as well as CAISO’s ability to assess cost causation to avoid cost shifting onto other ratepayers. The CPUC recommends that CAISO provide clarity and consistency regarding concurrences by clearly articulating that these projects primarily serve the large loads dependent on them rather than all ratepayers.
c.)
N/A
3.
Please provide your organization’s comments on section C. Requirements for co-located arrangements.
a. Please provide comments on terminology.
b. Please provide comments on serving co-located loads.
c. Please provide comments on cost allocation for co-located loads.
d. Please provide any other comments on this topic.
a.)
Several terms remain undefined and/or unclear in the co-location section of the Straw Proposal, including the Date of Service and the time of installation / operation of co-located generation. CPUC recommends that CAISO address this and any other ambiguities in the interest of clarity and transparency.
b.)
Co-located configurations can introduce significant complexity and both known and unforeseen design and operational vulnerabilities, regardless of whether the associated generation is behind-the-meter or in front-of-the-meter. As a state, the practice of pairing an existing large load with an existing generation resource - thereby creating co-located arrangements that were not originally intended - should be discouraged. Such large load-generation pairings should be conceived and engineered as integrated facilities from the outset. Additionally, air quality may be adversely affected if older generating units are brought back into service without appropriate safeguards.
CAISO does not propose any revisions to its existing frameworks governing behind-the-meter generation, gross load measurement, or the transmission access charge. Although CAISO cites California policies supporting self-generation and net energy metering, it does not fully address reliability and resource adequacy exposure from unaccounted for BTMG load. CAISO should demonstrate in its straw proposal that its planning processes have already accounted for the possibility that co-located generation could go offline and temporarily expose the full load to the transmission system.
c.)
CAISO has not addressed FERC’s direction regarding how netting rules for behind the meter generation (BTMG) for 50+ MW data center customers should be changed in its TAC mechanism. CAISO has not proposed BTMG netting changes for the TAC and argues that its current TAC structure is sufficient because BTMG reduces grid reliance. CAISO uses Gross Load as the primary billing determinant to calculate and assess TAC. BTMG that serves onsite load is netted out of the customer’s Gross Load calculation. However, BTMG that exceeds onsite load is included in Gross Load (as indicated in Appendix A of the CAISO Tariff and footnote 67 of the straw proposal). FERC might conclude that allowing BTMG netting that serves onsite load only results in inter-PTO cost-shifting for the transmission grid resources necessary to maintain standby capacity and reliability for these large BTMG customers.
If CAISO allows broad BTMG netting exemptions at the wholesale TAC level, the total regional revenue collected for a transmission zone with significant new BTMG will be artificially depressed. This would create regional cost-shifting across utility boundaries – shifting the high-voltage grid burden of large data centers with BTMG onto ratepayers in other PTO territories across California.
The CPUC can adopt retail rate tariffs with BTMG gross-demand billing rules to prevent cost-shifting between an IOU's data center and non-data center customers. However, downstream retail rates cannot prevent BTMG-driven cost-shifting across utility boundaries.
d.)
N/A
4.
Please provide your organization’s comments on section D. New transmission services for flexible large loads.
a. Please provide comments on the Flexible Interim Load Interconnection (FILI) offering.
b. Please provide comments on the Flexible Load Interconnection – Permanent (FLIP) offering.
c. Please provide any other comments on this topic.
a.)
CAISO proposes two new flexible load interconnection services that it claims will enable faster and more affordable interconnections: FILI and FLIP. CPUC staff look forward to seeing a final proposal that demonstrates how the CAISO’s and PTOs’ tariffs will interact, with respect to the FLIP.
b.)
See above.
c.)
CAISO has not committed to modeling market impacts of flexible vs. non-flexible large loads. Absent this, CPUC staff will not be able to accurately assess locational marginal price upward shifts, congestion cost increases, or local ancillary service procurement costs driven by non-flexible data center demands. CPUC needs granular market data to ensure that the retail rates and class revenue allocations that it adopts for data center customers accurately reflect the total costs of inflexible demand relative to flexible demand. Both class revenue allocation and non-compliance penalty design require detailed market impact information beyond what CAISO has committed to providing in its draft Straw Proposal.
CAISO outlines that both the proposed FILI and FLIP flexible service offerings offer value to large load customers (developers) by both allowing them to receive service earlier than a traditional firm offering would permit, and by avoiding the need to fund network upgrades. CAISO has also signaled its openness to a range of provisions and terms between PTOs and developers in these offerings – those provisions could potentially include reduced energy or capacity costs for the non-firm portion of the load. CPUC staff request that measures be in place to ensure resources are not being double counted and/or double compensated via different mechanisms.
5.
Please provide your organization’s comments on section E. Serving electrically proximate large loads.
CPUC staff generally agree with CAISO’s position that the tariff should not broadly enable interconnection customers to serve electrically proximate large loads. In addition to being legally and administratively difficult, the planning, engineering, and operation of electrically proximate large loads would be highly complex. CPUC staff also believe the piecemeal regulatory and operational organization could eventually create seams issues that may impose unforeseen reliability risks or cost shifts.
However, CPUC staff disagree with CAISO’s conclusion that no process is needed to address serving electrically proximate large loads. In circumstances where co-located generation and nearby load already exist, a defined process could allow CAISO to evaluate these configurations in a way that may reduce or eliminate network upgrades, accelerate energization timelines, and lower overall upgrade costs. Studying these facilities together with specified limits on generation output may provide operational benefits while still maintaining system reliability.
6.
Please provide your organization’s comments on the Operational Forecasting Requirements.
The Straw Proposal appears to defer to PTO tariffs to define the schedule and cadence for reporting in general and for operational forecasting in particular. CPUC staff encourage CAISO to pursue a coordinated approach consistent with the FERC Order’s requirements for clarity and consistency. CPUC staff recommend greater clarity as to when upgrades to be included in the TPP are identified and reported, before being integrated into the TPP.
The CAISO Straw Proposal suggests that PTOs are the appropriate parties to address concerns regarding speculative or duplicative requests that could confound forecasting efforts. However, the Straw Proposal does not indicate how the CAISO and PTOs would jointly address the prospect of duplicative requests that occur across multiple PTOs in the CAISO territory. At the least, addressing this concern implies a level of transparency and coordination between PTOs and CAISO, the mechanics of which should be made clear lest the final tariff changes fail to meet FERC’s requirements for clarity, consistency and protections against cost shifting.
7.
Please provide your organization’s comments on the proposed Technical Requirements.
CPUC staff are concerned that the Straw Proposal does not yet include a defined mechanism to ensure that the definition of Large Load developed by NERC is, and remains, consistent with that employed by CAISO and the PTOs. Additional details regarding that process would serve to help satisfy the transparency and consistency requirements of the FERC Order.
The FERC Order requires that tariff revisions be made to ensure consistent, clear, and transparent quantification of the costs and benefits associated with alternative transmission technologies that might reduce the need for additional system buildout. Without documentation of what cost savings these technologies bring, CPUC staff are concerned that it will be difficult or impossible to accurately determine if the least cost option is being selected, to the detriment of ratepayers. CPUC staff understand that CAISO may elect to defer to PTOs to perform these assessments and encourage the CAISO and PTOs to pursue consistency in satisfaction of Order requirements.
8.
Please provide your organization’s comments on the Technical Requirements under development.
The Large Load Technical Requirements Working Group (LLTRWG) continues to refine the technical requirements based on stakeholder feedback, additional system studies, operating experience, and the ongoing development of NERC Reliability Standards for computational loads.
Operating large loads paired with on-site generation introduces significant operational complexity. Even modest physical separation between the large load location and the associated generation can heighten that complexity, increasing both safety and reliability risks. There is also a risk that developers may seek to return previously retired power plants to service, including units retired for air quality concerns, in order to take advantage of co-location opportunities. Given these considerations, CPUC staff does not support broadly allowing co-located large loads and generation. CPUC staff appreciates CAISO’s engagement with NERC on these matters.
The Straw Proposal also notes that the following operational requirements identified in the FERC Order to Show Cause have not been addressed:
The CPUC is particularly interested in a clear plan regarding the latter two issues. In the event of a WECC-wide disturbance, having reliable communication channels and control capabilities for individual large load facilities could be essential for maintaining system stability.
9.
Please provide any additional comments on the straw proposal or Aug 19 meeting discussion.
CPUC staff look forward to a holistic presentation of the PTO and CAISO proposals so that stakeholders may better understand the interaction of policy mechanisms intended to provide the clear and consistent policy response required by the Order. In particular, CPUC staff hope to better understand relevant policy mechanisms that will help ensure that ratepayers be held harmless for the long-term, rate-based costs imposed on the system by large load customers at the revenue requirement level. CPUC staff hope that the Final Proposal and the scheduled workshop include a joint presentation from the PTOs and an opportunity for stakeholders to provide the necessary feedback to protect against regulatory gaps.
California Public Utilities Commission - Public Advocates Office
Submitted 09/02/2026, 03:47 pm
1.
Please provide your organization’s comments on section A. Transmission Service to eligible customers.
a. Please provide comments on the definition of large loads.
b. Please provide comments on the large load application process and interconnection study procedures.
c. Please provide comments on the large load operational requirements.
d. Please provide any other comments on this topic
The Public Advocates Office at the California Public Utilities Commission (Cal Advocates) provides these comments on the California Independent System Operator’s (CAISO) Large Load Considerations Straw Proposal, and August 19, 2026 stakeholder meeting. Cal Advocates is an independent ratepayer advocate with a statutory mandate to obtain the lowest possible rates for utility services, consistent with reliable and safe service levels and the state’s environmental goals.[1]
- Definition of Large Loads
CAISO should exclude a Megawatt (MW) threshold from the definition of large-loads.
In response to the Federal Energy Regulatory Commission’s (FERC) concern[2] that the CAISO does not define large-loads, CAISO suggests a definition could be “[a]n End User located at a single site interconnecting to the CAISO Controlled Grid, and that has a peak load of 50 [megawatt] MW or greater.”[3] FERC proposed a definition with greater specificity about customer type, transmission voltage levels, and co-location arrangements.[4] CAISO states that it removed the voltage condition from FERC’s proposed definition because the interconnection at the “CAISO Controlled Grid” effectively describes that the load is transmission-connected.[5] Similarly, interconnecting to the CAISO Controlled Grid eliminates the need for a MW size threshold because customers interconnecting to the transmission system are large enough to pose unique challenges to the interconnected system. Therefore, a MW size threshold is unnecessary to define a large-load and should be excluded from the definition. Large-loads should be simply defined as “an End User located at a single site interconnection to the CAISO Controlled Grid.”
- Large Load Application Process and Interconnection Study Procedures
CAISO should refrain from studying large-loads until the requesting customer has satisfied readiness requirements.
To deter speculative load, CAISO should refrain from studying and approving network upgrades for large-loads until the large-load completes readiness requirements. Readiness requirements include proof of site control, executed interconnection agreements, procurement of long-lead time materials, and financial commitments.[6] FERC suggests that CAISO’s tariff fails “to deter speculative or duplicative requests for transmission service by Eligible Customers on behalf of large loads.”[7] CAISO proposes that the responsibility to deter speculation is more appropriately held by the Participating Transmission Owners (PTOs). CAISO also notes the CEC’s long-term demand forecasts have a process to address speculative large-load requests.[8] However, CAISO has a responsibility to identify and develop cost-effective transmission solutions for the future needs of the ISO-controlled transmission grid. Thus, CAISO can and should take a meaningful role in avoiding the inclusion of network upgrades for speculative large-loads in system planning. FERC supports having independent system operators (ISO) require the completion of milestones in order to ensure that large-load requests are “more viable and more likely to materialize as planned.”[9] CAISO should require the completion of readiness requirements before studying or approving network upgrades necessary to accommodate large-load interconnections.
CAISO should require the PTO to demonstrate the large-loads’ completion of readiness requirements as part of the CAISO’s load interconnection request and study process. In response to FERC’s Order, CAISO proposes “enhanced data sharing and process alignment between the CAISO and the PTOs to further streamline the load interconnection request and study process.”[10] As a part of this data sharing, CAISO should require the PTO to demonstrate the large-load’s proof of 100% site control,[11] financial commitments, and executed and binding interconnection agreements.
CAISO encourages the PTOs to align with the CAISO Resource Interconnection Standards (RIS) for enhanced clarity and consistency.[12] Currently, the RIS for interconnection customers requires proof of site control and a deposit prior to the initiation of a study.[13] The RIS also requires interconnection customers to pay commercial readiness deposits based on required network upgrades. CAISO should hold large-loads applying for transmission service through the PTOs to the standards expressed in the CAISO RIS. CAISO should refrain from studying or approving network upgrades necessary to accommodate large-loads until the customer meets readiness requirements.
CAISO also points to the CEC’s Integrated Energy Policy Report (IEPR) as a venue to address FERC’s concerns regarding speculative or duplicative large load interconnection requests.[14], [15] CAISO highlights that the CEC uses confidence levels to adjust the requested capacity in the IEPR forecast. Large-load applications with signed agreements with the utility for electric service are included in the highest confidence group. However, the CEC’s current confidence groups may be insufficient to curb speculative load in transmission planning.[16]
CAISO should refrain from using its concurrence process for approving costly network upgrades for large-load interconnection projects.
CAISO seeks several clarifications to its tariff regarding the use of the concurrence process in the context of large-loads. The concurrence process allows for a degree of uncertainty that is unsuitable for approving costly transmission projects for large-load customers. CAISO’s clarifications on the concurrence process establish a process for speculative large-loads to deviate from the Transmission Planning Process’s (TPP) more formalized demand forecast and California Public Utilities Commission (CPUC) resource portfolios.[17] PTOs request concurrence for an upgrade based on their own load forecast and planning assumptions, which take the place of the forecasting assumptions in the TPP. Confidence level assumptions underlying the CEC’s IEPR process are meant to reduce the levels of uncertainty incorporated into system planning. Large-loads that receive concurrence do not have to align with the confidence levels embedded into the TPP or complete any readiness requirements prior to CAISO’s review and concurrence. The proposed clarifications to the concurrence process therefore give PTOs an opportunity to inject speculative loads into transmission planning and could impair the state’s aim to coordinate resource planning. In addition, CAISO’s concurrence process does not include any transparent evaluation of alternative transmission technologies like Grid Enhancing Technologies (GETs) or Energy Storage.
CAISO should refrain from using its concurrence process for approving transmission projects for large-load interconnections. Instead, CAISO should study projects proposed by PTOs as an additional sensitivity case in that year’s TPP reliability modeling scenarios or hold approval until the load can be sufficiently studied in a future TPP study year.
[1] Cal. Pub. Util. Code § 309.5.
[2] FERC, Order Instituting Proceeding Under Section 206 of the Federal Power Act (FERC Order), June 18, 2026, ¶ 48. (“We then consider whether CAISO’s Tariff and/or the TO Tariffs are unjust and unreasonable without certain elements. First, we consider whether CAISO’s Tariff and/or the TO Tariffs lack sufficiently clear and consistent tariff provisions establishing an appropriate definition of large load, as a separate category of load.”)
[3] CAISO, Large Load Considerations Straw Proposal (Straw Proposal), August 12, 2026, at 9.
[4] FERC Order ¶ 57.
[5] Straw Proposal at 10.
[6] FERC Order ¶ 55.
[7] Straw Proposal at 14.
[8] Straw Proposal at 17.
[9] FERC Order ¶ 55.
[10] Straw Proposal at 14.
[11] CAISO, Fifth Replacement Tariff, August 5, 2026, Appx. A. (Site control is defined as the “exclusive land right to develop, construct, operate, and maintain the Generating Facility over the term of expected operation of the Generating Facility. Site Control may be demonstrated by documentation establishing: (1) ownership of, a leasehold interest in, or a right to develop a site of sufficient size to construct and operate the Generating Facility; (2) an option to purchase or acquire a leasehold site of sufficient size to construct and operate the Generating Facility; or (3) any other documentation that clearly demonstrates the right of Interconnection Customer to exclusively occupy a site of sufficient size to construct and operate the Generating Facility. The CAISO will maintain acreage requirements for each Generating Facility type on its Website.”)
[12] Straw Proposal at 15.
[13] CAISO, Fifth Replacement Tariff, August 5, 2026, Appx. KK, secs. 3.5.1. and 14.4.1.
[14] Straw Proposal at 17.
[15] The IEPR produces a demand forecast which is incorporated into CAISO’s transmission planning process (TPP).
[16] The CEC’s use of “signed agreement” to categorize applications is unclear and may result in counting early and uncertain applications as erroneously having a signed agreement. See Cal Advocates Comments on the December 17, 2025, California Energy Commission (CEC) Integrated Energy Policy Report (IEPR) Commissioner Workshop on Energy Demand Forecast Results, December 31, 2025 (Cal Advocates Comments on CEC IEPR), at 1.
[17] Straw Proposal at 16.
2.
Please provide your organization’s comments on section B. Framework to prevent cost-shifting.
a. Please provide comments on roles and responsibilities to prevent cost shifting.
b. Please provide comments on data transparency.
c. Please provide any other comments on this topic.
- Roles and Responsibilities to Prevent Cost-Shifting
CAISO PTOs do not have established mechanisms to effectively prevent cost-shifting of network upgrades from large-loads to ratepayers.
The FERC Order requires CAISO to address any cost-shifting risk caused by the process of evaluating the transmission facilities needed to serve large-loads.[1] In its straw proposal, CAISO states that cost-shifting risks are mitigated to the extent that a “PTO requires a large load developer to contribute to the costs of constructing network upgrades on an upfront basis.”[2] However, the extent that a PTO actually requires such contributions is not established; it is uncertain at this point. CAISO should revise its statement to accurately reflect current conditions and establish how it will address the cost-shifting risk.
First, PTOs have not yet established protections such as upfront payments for network upgrades. Therefore, CAISO cannot assume that PTOs will mitigate cost-shifting risks. As of the time of these comments, most large-load requests in the CAISO region are subject to Pacific Gas and Electric Company’s (PG&E) interconnection process under Rules No. 15/16 and, potentially, PG&E’s new Electric Rule No. 30 (pending CPUC consideration). The current interconnection process and PG&E’s proposal for Rule 30 do not require customers to contribute to network upgrade costs on an upfront basis. Retail interconnections under PG&E’s Rule 30 proposal creates a risk that large-loads will shift costs associated with all CAISO transmission facilities onto existing CAISO users. Importantly, PG&E opposes recommendations in the Rule 30 proceeding to include an upfront advance for network upgrades and refund mechanism based on actual customer revenue to curtail those risks.[3]
CAISO also notes that other account adjustments that prevent cost-shifting can be implemented in PTO tariffs. Proposals in the Rule 30 proceeding include account adjustment mechanisms such as minimum demand charges and exit fees. However, implementation of these terms will depend on a final CPUC decision in the Rule 30 proceeding, which will not likely come until 2027.[4]
Second, CAISO incorrectly states that “contributions offset costs that would otherwise have been added to the PTO’s rate base and included in the regional transmission access charge (TAC).”[5] Upfront contributions alone do not offset costs in the long-term because they are usually refunded. For example, the CPUC has released Draft Resolution E-5455 approving a data center interconnection agreement that requires refundable upfront cost payments for both dedicated and networked transmission facilities. Refundable upfront payments require large-load customers to take temporary responsibility for costs, which mitigates cost-shifts in the short-term. In the long-term, the PTOs will reimburse large-load customers via a refund process. These costs would be incorporated into the PTOs’ revenue requirements and paid for by all TAC ratepayers through retail and wholesale rate allocations. Cost-shifts would occur if the large-loads don’t sustain at the levels relative to the maximum loads requested for transmission service over the lifespan of the transmission infrastructure (40-50 years).
CAISO should revise its proposal in the cost-shifting section to reflect that PTOs have not established at-scale interconnection terms requiring large-loads to pay for network upgrade costs that sufficiently address cost-shifting risks. CAISO should also clarify that costs contributed through upfront payments are recoverable through the CAISO TAC over the lifetime of the transmission infrastructure project if reimbursed. As a short-term mitigation measure, PTO requirements for upfront contributions are not sufficient to prevent cost-shifting of the transmission costs required for large-loads. CAISO should encourage PTOs to pair upfront contributions with a slower recovery period that incorporates costs into rates as the underlying loads materialize on the system over time.
- Data Transparency
CAISO’s transparency requirements should include information identifying the portions of upgrades attributable to large-load customer types (e.g., electric vehicle charging and data centers) and general load growth.
The FERC Order states that transparency measures related to network upgrades for large-loads appear necessary for public utility commissions and other state regulators “to understand which transmission costs are caused by which transmission customers” and to “protect residential and small commercial customers.”[6] CAISO proposes to address this concern by following the Order’s direction to publish information that identifies: (1) aggregated amounts of large-load additions, (2) planned network upgrades needed to serve each large-load, and (3) the cost estimates for each upgrade (collectively the “proposed information”).[7] CAISO’s proposal is not sufficient to fully fix transparency issues, because it is unclear whether the proposed information can be solely attributed to large-loads.
Network upgrades can address multiple needs at once, so it is entirely possible that only a portion of an upgrade is necessary to serve large-load. The proposed information is not specific enough to determine whether a network upgrade is needed but for the addition of a large-load request, and the associated costs.[8] That information is important for state regulators and stakeholders to understand so they may require PTOs to use the information in transparent customer-specific approaches to large-load cost responsibility.
Stakeholders can gain visibility into large-load cost causation through the proposed information CAISO ushers through the FERC Order. Using this information, PTOs may perform cost calculations that determine system-wide averages and non-specific costs distributed equally among large-loads. While more general than customer-specific costs, these costs can be attributed to large-load customers during the interconnection process. To make the information useful for PTOs with retail load interconnections, CAISO should establish: (1) a clear timeline for data releases that align with the TPP, or (2) a new, transparent process focused solely on large-loads.
In line with FERC’s direction to ensure data transparency and retail cost allocation, CAISO should consistently provide information that identifies the portion of upgrades that are attributable to large-loads and the large-load type. CAISO should post the proposed information, as well as: (1) the portion of each network upgrade for which the large-load addition relies on for each transmission service request, (2) the portion of each network upgrade that would not be needed but for large-loads for each transmission service request, and (3) cost estimates for each portion of each upgrade.
Lastly, CAISO should clarify which large-load customer types are driving which network upgrades. CAISO refers to data center loads, computing loads, and AI-training data centers as drivers of large-load electricity demand in California.[9] CAISO should memorialize a definition for data center in its tariff to distinguish between large-load customer types. Other large-load types, such as electric vehicles and industrial electrification, are major drivers of demand growth in California. Due to differences in scale, load behavior, and operational dates, data centers may require more dedicated or accelerated network upgrades than other large-load types. To determine if additional protections or new rate classes for certain customer types are necessary, the CPUC needs insight into how customer types are impacting the grid and network upgrade costs. In its transparency measures, CAISO should specify that it will identify the types of large-load customers driving network upgrades to support fair cost allocation and recovery.
[1] FERC Order ¶ 67, 83.
[2] Straw Proposal at 26.
[3] CPUC Application (A.) 24-11-007, Pacific Gas and Electric Company’s (U 39 E) Limited Opening Post-Hearing Brief at 10-15.
[4] CPUC A.24-11-007, Order Extending Statutory Deadline, August 24, 2026.
[5] Straw Proposal at 26.
[6] FERC Order at ¶ 68.
[7] Straw Proposal at 27.
[8] “But-for” costs are needed to serve a new customer compared to costs that provide broader system benefits. See Lawrence Berekeley National Lab, Speed to Power: Solutions for Accelerating Large-load Connections, June 2026, available at https://eta-publications.lbl.gov/sites/default/files/2026-06/lbnl_large_loads_speed_to_power_final_1.pdf.
[9] Straw Proposal at 1, 4, 5, and 18.
3.
Please provide your organization’s comments on section C. Requirements for co-located arrangements.
a. Please provide comments on terminology.
b. Please provide comments on serving co-located loads.
c. Please provide comments on cost allocation for co-located loads.
d. Please provide any other comments on this topic.
Cal Advocates has no comments on section C at this time.
4.
Please provide your organization’s comments on section D. New transmission services for flexible large loads.
a. Please provide comments on the Flexible Interim Load Interconnection (FILI) offering.
b. Please provide comments on the Flexible Load Interconnection – Permanent (FLIP) offering.
c. Please provide any other comments on this topic.
CAISO’s proposed flexible service programs should include mandatory curtailment requirements, control technologies, and protection systems.
FERC requests that CAISO address service options for flexible large-loads and terms for remote disconnection of large-loads in stressed grid conditions.[1] CAISO proposes two new flexible load interconnection services: an interim flexible option and a permanent flexible option.[2] CAISO states that the PTOs should implement remote disconnections of large-loads.[3] CAISO is not sufficiently responding to the FERC Order by suggesting the PTOs should be responsible for remote disconnections and protection systems necessary to implement flexible load service. CAISO should establish enforceable requirements for curtailment for flexible large-loads, including requirements for the communications, control, protection, and remote disconnection capabilities necessary to ensure curtailment can be implemented when required.
CAISO also notes that for “a large-load requesting non-firm interconnection service, the PTO may need the CAISO to help memorialize and sign on to the operational procedures necessary to provide that service through new pro-forma non-firm service agreements.”[4] CAISO fails to propose ISO requirements that are necessary to ensure benefits materialize from flexible agreements and flow to system users. Any non-firm service agreement between CAISO and a PTO or large-load should establish the curtailable amount of a customer’s load and include control requirements for the curtailment to be implemented.
[1] FERC Order at ¶ 63, 104.
[2] Straw Proposal at 21.
[3] Straw Proposal at 21.
[4] Straw Proposal at 24.
5.
Please provide your organization’s comments on section E. Serving electrically proximate large loads.
Cal Advocates has no comments on section E at this time.
6.
Please provide your organization’s comments on the Operational Forecasting Requirements.
Cal Advocates has no comments on Operational Forecasting Requirements at this time.
7.
Please provide your organization’s comments on the proposed Technical Requirements.
Cal Advocates has no comments on the proposed Technical Requirements at this time.
8.
Please provide your organization’s comments on the Technical Requirements under development.
Cal Advocates has no comments on Technical Requirements under development at this time.
9.
Please provide any additional comments on the straw proposal or Aug 19 meeting discussion.
Cal Advocates has no additional comments at this time.
Constellation
Submitted 09/02/2026, 03:56 pm
1.
Please provide your organization’s comments on section A. Transmission Service to eligible customers.
a. Please provide comments on the definition of large loads.
b. Please provide comments on the large load application process and interconnection study procedures.
c. Please provide comments on the large load operational requirements.
d. Please provide any other comments on this topic
a. Definition of Large Loads
Constellation generally supports CAISO's proposed definition of large loads. The definition appropriately focuses on transmission-connected end-use customers with peak demand of 50 MW or greater while maintaining flexibility as industry practices and NERC requirements continue to evolve. CAISO should clarify how it intends to apply the 50 MW threshold to phased projects, expansions of existing facilities, and multiple loads that share a point of interconnection.
b. Large Load Application Process and Interconnection Study Procedures
Constellation generally supports CAISO's proposed enhancements to large load application, study, and coordination procedures. Improved information sharing, coordination between Participating Transmission Owner (PTO) load interconnection studies and CAISO processes, and greater visibility into large load characteristics should improve planning and operational awareness while supporting timely interconnection of new loads.
The study framework should clearly explain the respective responsibilities of CAISO, the PTO, and the interconnection customer. It should also establish clear application requirements, a delineation of the studies to be conducted, study milestones and timelines, data-sharing procedures, and timelines for communicating material changes to study assumptions or required upgrades.
CAISO and the PTOs should avoid duplicative studies and inconsistent data requests. Customers should receive access to the assumptions, methods, and results that support material upgrade or operating requirements, subject to appropriate confidentiality protections.
c. Large Load Operational Requirements
Constellation generally supports CAISO's efforts to develop operational requirements necessary to maintain reliability as large loads become a larger portion of system demand. Enhanced forecasting, telemetry, operational data, and communication requirements appear reasonable given the unique operating characteristics and scale of many emerging large load customers.
2.
Please provide your organization’s comments on section B. Framework to prevent cost-shifting.
a. Please provide comments on roles and responsibilities to prevent cost shifting.
b. Please provide comments on data transparency.
c. Please provide any other comments on this topic.
a. Roles and Responsibilities to Prevent Cost Shifting
Constellation supports assigning infrastructure costs to customers whose interconnection requests cause those costs. We also support CAISO's continued coordination with PTOs as they develop complementary tariff provisions to ensure that related tariff development and revisions apply consistent standards and do not create conflicting or duplicative obligations.
b. Data Transparency
Constellation supports CAISO's proposal to enhance transparency regarding large load interconnection activity, planned network upgrades, and associated cost information. Improved transparency should benefit developers, regulators, transmission customers, and other stakeholders
3.
Please provide your organization’s comments on section C. Requirements for co-located arrangements.
a. Please provide comments on terminology.
b. Please provide comments on serving co-located loads.
c. Please provide comments on cost allocation for co-located loads.
d. Please provide any other comments on this topic.
b. Serving Co-Located Loads
Constellation appreciates CAISO’s efforts to clarify the treatment of co-located loads and generally supports a framework that maintains reliability while accommodating different project configurations. CAISO should establish an explicit, study-based pathway to address scenarios where a generator serves co-located load while remaining available to the grid and retaining associated interconnection rights to the extent supported by the facility’s configuration, operating capabilities, and reliability impacts. Specifically, it would be improper for CAISO to treat every co-location arrangement involving existing generation as a retirement even when the generator intends to continue to supply energy to the wholesale market and provide reliability to the grid.
During the August 19 stakeholder workshop, CAISO emphasized the need to evaluate the reliability implications of generation serving co-located loads. CAISO’s prior Retention of Interconnection Service and Deliverability for Retirements and Repowers Final Proposal states that a generating resource subject to a Participating Generator Agreement (PGA) that intends to terminate participation in the CAISO wholesale market while continuing to serve load through applicable retail programs would be treated as a permanent-retirement, and subject to a Reliability-Must-Run (RMR) review:
“For clarity, the ISO considers any generation that is subject to a PGA and intends to terminate participation in the ISO wholesale market but continues generating to serve load through applicable retail programs, to also be subject to the retirement process as a generator that is permanently retiring (Retirement Scenario 3). This would include, for example, distribution-connected or transmission-connected participating resources that wish to exit from the ISO markets to serve onsite load. Although such generators will continue to produce electricity, their exit from the wholesale markets will be treated as a retirement, including triggering a reliability-must-run review.” [1]
However, the prior initiative does not clearly address co-location arrangements in which the generator could continue to participate in the wholesale market and support reliability, including:
- Only a portion of a generating facility serves co-located load.
- The generation owner could sell into wholesale markets when it is not serving co-located load.
- The co-located load can reduce or interrupt consumption in response to CAISO instructions, transmission constraints, or defined reliability conditions, allowing the co-located generation to supply the grid during times of reliability need (potentially under CAISO’s proposed FILI and FLIP services)
CAISO indicated during the August 19 workshop that it does not intend to apply a rigid framework to colocation arrangements and remains open to project-specific approaches. Constellation supports that position and believes that CAISO should accomplish it through a defined tariff pathway rather than leave these arrangements to case-by-case discussions.
CAISO should clarify that serving co-located load does not, by itself, establish an intent to terminate wholesale market participation or trigger Retirement Scenario 3. That conclusion is particularly important where the generator retains the ability to inject energy, provide ancillary services, support local reliability, and/or offer eligible capacity from all or part of the facility. It also aligns with the current tariff language that termination may occur “in the event that the Participating Generator no long wishes to submit Bids and transmit Energy over the CAISO Controlled Grid.”[2] CAISO should evaluate the combined generation and load configuration and its enforceable operating commitments rather than apply a categorical retirement designation based solely on the presence of co-located load.
CAISO should therefore establish an explicit pathway for existing resources that continues to participate in wholesale markets while serving co-located load as an alternative to retirement (Scenario 3) or repowering (Scenario 1) for existing resources. Under that alternative, CAISO should evaluate these arrangements through project-specific studies and enforceable operating requirements to determine the interconnection service capacity, deliverability, and wholesale market capabilities that the generator may retain based on its ability and intent to continue participating in the wholesale market and providing energy to the grid. The review should consider:
- The portion of the generating facility committed to serving co-located load.
- The generation capability that remains available to CAISO (which may vary over time).
- The co-located load’s maximum grid withdrawal and expected transmission use.
- The load’s ability to reduce or interrupt consumption (potentially under FILI or FLIP).
- The response time, duration, availability, and verification of any load-reduction obligation.
- Metering, telemetry, scheduling, dispatch, and communications requirements.
- Necessary limitations on simultaneous load service and wholesale injections.
- The arrangement’s transmission, operational, resource adequacy, and local reliability effects.
Flexible load capability should be central to this evaluation. A co-located large load may be able to reduce or interrupt consumption during system emergencies, transmission constraints, or other defined operating conditions under FILI, FLIP, or some other form of interruptible service. It may also qualify to participate as demand response or another form of dispatchable load. Where those capabilities are measurable, enforceable, and supported by appropriate metering, telemetry, and verification, CAISO should evaluate the extent to which the associated generator may continue to provide wholesale energy, ancillary services, resource adequacy capacity, or other reliability support, consistent with demonstrated operating capabilities, reliability requirements, and applicable market rules.
The relevant question should be what wholesale services the combined generation and load configuration can provide. Where reducing the co-located load can release generation capability for CAISO dispatch, that operating capability should inform the generator’s retained interconnection rights and eligibility to participate in CAISO markets, subject to applicable deliverability, qualifying capacity, availability, and performance requirements.
At a minimum, even if the co-located generation does not retain its deliverability and can no longer provide RA capacity, it should be able to retain its interconnection and continue to participate in energy and ancillary service markets. CAISO should also consider how co-location arrangements taking service under FILI and FLIP or other similar non-firm service (or participation in DR or Participating Load) might affect the treatment of existing generation serving co-located load.
Repowering may provide one path for retaining interconnection service capacity and deliverability, but CAISO should not make it the exclusive alternative to retirement. Requiring repowering (Scenario 1) where an existing generator remains capable of providing wholesale energy or reliability support could remove useful capability without a demonstrated reliability basis. It could also discourage arrangements under which a flexible large load helps support the continued operation of existing generation while remaining available to reduce consumption during constrained system conditions.
CAISO should clarify in its next proposal:
- When serving co-located load will terminate a generator's ability to participate in wholesale markets, and when a generator may retain full or partial wholesale market participation based on the facility's configuration and operating characteristics.
- Whether Retirement Scenario 3 applies when a generator intends to retain all or some wholesale market participation, and can continue to provide wholesale market services.
- How CAISO will treat existing generation that intends to remain available when the co-located load interrupts or reduces consumption.
- Whether an interruptible or dispatchable co-located load may participate as Demand Response or through another CAISO market construct, such as Participating Load.
- How verified load flexibility will affect the generator’s retained interconnection service capacity, deliverability, and eligibility to provide energy, ancillary services, resource adequacy capacity, or other reliability support.
- When existing interconnection agreement amendment and post-commercial-operation-date modification procedures may support these arrangements.
- What studies, operating agreements, controls, metering, telemetry, and verification requirements would apply.
Constellation supports CAISO’s statement that it does not intend to apply a rigid framework and remains open to project-specific approaches. CAISO should implement that position through a defined tariff pathway, not leave it to discretionary case-by-case discussions. The pathway should preserve existing generation rights to the extent supported by studies and enforceable operating conditions, prevent incompatible or duplicative use of those rights, protect other customers from inappropriate cost shifts, and retain energy, capacity, and reliability capability that remains available to the system.
d. Any Other Comments
Constellation appreciates CAISO’s clarification that existing tariff mechanisms, including interconnection agreement amendments and post-commercial-operation-date modifications, may provide flexibility for existing resources. CAISO should explain how those mechanisms would apply to co-location arrangements and identify any additional tariff procedures needed to implement the study-based pathway described above.
[1] See CAISO, Retention of Interconnection Service and Deliverability for Retirements and Repowers, Final Proposal, at 4–5 (June 23, 2026).
[2] CAISO Tariff Appendix B.2., Participating Generator Agreement Section 3.2.2, pg.3
4.
Please provide your organization’s comments on section D. New transmission services for flexible large loads.
a. Please provide comments on the Flexible Interim Load Interconnection (FILI) offering.
b. Please provide comments on the Flexible Load Interconnection – Permanent (FLIP) offering.
c. Please provide any other comments on this topic.
a. FILI Offering and b. FLIP Offering
Constellation generally supports CAISO's proposal to create flexible service offerings that accelerate large load development and reduce unnecessary transmission upgrades.
CAISO clarified during the stakeholder process that FILI and FLIP are intended primarily as transmission and interconnection solutions to address local transmission constraints and upgrade timing considerations, rather than resource adequacy or broader system capacity needs. Constellation supports that approach.
Constellation understands that CAISO intends these options to be tailored to individual interconnection customer requests. As the proposal evolves, CAISO should provide additional clarity regarding:
- Curtailment triggers and operating conditions;
- How curtailment parameters will be established;
- Deployment priorities;
- Scheduling treatment;
- The relationship between operational restrictions and study assumptions; and
- Potential interactions with scheduling, dispatch, and price formation.
While these services will likely be highly project-specific, additional transparency regarding implementation will improve predictability for developers and market participants and help stakeholders better understand any potential market impacts.
c. Any Other Comments
Constellation supports the development of FILI and FLIP as flexible transmission and interconnection solutions for large loads. As discussed above, it would be helpful for CAISO to specify how FILI and FLIP might apply to colocation arrangements, including those involving existing generation resources— in particular the implications for generator deliverability and continued participation in wholesale markets.
As these offerings evolve, Constellation also encourages CAISO to provide additional transparency regarding deployment protocols, operational implementation, and interactions with scheduling and market processes. Additional information will help stakeholders better understand any potential impacts on dispatch outcomes, price formation, and broader market signals.
5.
Please provide your organization’s comments on section E. Serving electrically proximate large loads.
Constellation has no specific comments on this section at this time.
6.
Please provide your organization’s comments on the Operational Forecasting Requirements.
Constellation supports CAISO's efforts to improve operational visibility into large loads and agrees that enhanced forecasting, telemetry, and operational data requirements are likely necessary given the unique characteristics of many emerging large-load customers.
We generally support CAISO's proposal to rely on existing Load Serving Entity and Scheduling Coordinator structures rather than creating direct scheduling obligations for large load customers.
Constellation encourages CAISO to provide additional detail in future proposals regarding how large-load forecasts will be incorporated consistently across day-ahead and real-time operational processes.
7.
Please provide your organization’s comments on the proposed Technical Requirements.
Constellation generally supports the continued development of technical requirements intended to ensure reliable operation of large loads and encourages CAISO to remain aligned with evolving NERC reliability standards and industry practices.
8.
Please provide your organization’s comments on the Technical Requirements under development.
Constellation has no specific comments on this section at this time.
9.
Please provide any additional comments on the straw proposal or Aug 19 meeting discussion.
Constellation supports CAISO's efforts to facilitate large-load development while maintaining reliability and minimizing unnecessary transmission investment. The proposal represents an important step toward providing California with the tools necessary to support continued economic growth, data center development, advanced manufacturing, and other large load investments.
As CAISO finalizes this initiative, Constellation urges CAISO to work closely with PTOs ensure that related tariff revisions support open access, competitive outcomes, efficient interconnection processes, and timely development of new load.
Constellation also encourages continued coordination among CAISO, the California Public Utilities Commission (CPUC), the California Energy Commission (CEC), and other state agencies on broader policy issues that extend beyond transmission interconnection procedures. In particular, co-located load and generation arrangements raise important questions regarding long-term load forecasting assumptions, resource adequacy treatment, reliability planning, and the role that flexible large loads can play in supporting grid reliability. Coordination between CAISO and the state agencies will help ensure that planning, procurement, interconnection, and reliability frameworks produce fair and competitive outcomes.
CAISO should also coordinate its treatment of co-located generation with the flexible service concepts proposed through FILI and FLIP. As discussed above, the next proposal should provide clear, coordinated pathways for flexible large loads and co-located generation. Those pathways should reflect each arrangement’s actual transmission use and operating capability, preserve demonstrable wholesale market and reliability value, protect other customers from inappropriate cost shifts, and avoid categorical treatment where studies and enforceable operating requirements can address the identified reliability concern.
KritiGrid
Submitted 08/31/2026, 09:04 pm
1.
Please provide your organization’s comments on section A. Transmission Service to eligible customers.
a. Please provide comments on the definition of large loads.
b. Please provide comments on the large load application process and interconnection study procedures.
c. Please provide comments on the large load operational requirements.
d. Please provide any other comments on this topic
a. Definition of large loads
No comment.
b. Application process and interconnection study procedures
No comment.
c. Large load operational requirements
The Straw Proposal's interconnection data requirements ask each large load to state its "Curtailment capability" and "Expected hourly flexibility capability" (p. 22). That disclosure only runs one way. The load must declare what flexibility it can offer, but nothing requires anyone to tell the load what flexibility it will actually be asked for.
The requirement should run both ways. Any FILI or FLIP offer should be accompanied by a disclosure of expected curtailment exposure at the proposed point of interconnection, covering: expected curtailment hours per year, given as a distribution and not a single number; the distribution of consecutive-hour episode lengths (a hundred scattered hours and a hundred hours arriving in twelve-hour blocks are different obligations, and they price differently); seasonal and diurnal concentration; and the transmission elements whose binding drives the exposure.
This is a disclosure requirement, not a cap. It does not constrain the CAISO or the PTO in operations. The figure should be expressly informational: an expectation published to be relied on in underwriting, not a level the CAISO undertakes to stay within. We recognize the tension in that sentence. A number published for use in financing will be relied on, and a disclosure that is relied on can drift into being treated as a commitment. We are not asking the CAISO to carry that risk. The disclosure should carry an express non-reliance term: that it creates no entitlement, no cause of action, and no limit on curtailment actually instructed, and that a load taking flexible service accepts the operational obligation as written in the agreement rather than as estimated in the disclosure. It requires only that the party being asked to accept an interruption right be told what that right is expected to be worth. Detail in the attachment, Section 2.
d. Any other comments on this topic
The Large Load Technical Requirements Straw Proposal of June 15, 2026 states that it "is focused specifically on technical requirements associated with interconnection and reliable grid operation," and that it "does not establish or address broader planning, market participation, scheduling, or operational requirements applicable within the ISO Balancing Authority Area" (p. 2). That track therefore defines with real precision what a large load must be able to do, while expressly leaving aside what it will be asked to do. This Straw Proposal, in turn, creates the services and declines to bound them. The exposure question seems to be falling between the two workstreams, not within either.
2.
Please provide your organization’s comments on section B. Framework to prevent cost-shifting.
a. Please provide comments on roles and responsibilities to prevent cost shifting.
b. Please provide comments on data transparency.
c. Please provide any other comments on this topic.
a. Roles and responsibilities to prevent cost shifting
No comment.
b. Data transparency
This is our principal comment.
We support the proposed framework. The CAISO states that "cost data should be transparent and can be provided on the CAISO website in a searchable format," and proposes "to memorialize these transparency requirements in its tariff" (pp. 26-27), across three categories: aggregate proposed large load additions by pricing zone; planned network upgrades by equipment type; and cost estimates for each such upgrade.
Our observation concerns the stated purpose. The CAISO explains that transparency matters "both to aid large load developers in making efficient siting decisions as well as to provide information critical for state regulators to ensure fair cost allocation at the retail level" (p. 26).
The first of those purposes is not served by cost data alone once flexible service exists. For a load taking firm service, upgrade cost is the material siting variable and the proposed disclosures address it well. For a load taking FILI or FLIP, the defining term of the deal is not the upgrade cost it avoids — it is the curtailment it accepts in exchange. A developer comparing two candidate points of interconnection under flexible service can now learn what each would cost to upgrade, and cannot learn what each would cost to operate.
So our recommendation is narrow: add expected curtailment exposure as a fourth category to a transparency framework the CAISO has already agreed to build and to memorialize in its tariff. Nothing more than a fourth category.
On who produces it, no new machinery is needed either. The CAISO already proposes to post the other three categories in a searchable format, and in the same passage "encourages the PTOs to memorialize tariff requirements to adopt large load queue spreadsheets as it does for wholesale generator interconnection customers" (pp. 26-27). The fourth category can travel the same path: the PTO supplies the figure alongside the queue spreadsheet, and the CAISO posts it with the rest. The underlying inputs are contingency and load-flow cases, shift factors, and planned outage and in-service schedules, all of which are the PTO's, so production sits with the party that already holds them.
We should be plain about what that asks of a PTO. A queue spreadsheet is an administrative record; a forward exposure estimate is a forecast, and a forecast carries review and assurance burden that a spreadsheet field does not. If that burden is what makes this slow, there is a lighter first step that delivers most of the value: publish the realized history rather than a forecast. Hours above a stated congestion threshold at each node, for the last two calendar years, requires no forward-looking judgment from anyone and is already implicit in settlement data the CAISO publishes. A developer can underwrite against a history. Treat the forward estimate as a second phase if the first proves useful.
c. Any other comments on this topic
This is feasible today, from data the CAISO already publishes. We have demonstrated it across 44 settlement locations in the PG&E service area over two complete calendar years, using only the congestion component of the day-ahead price from the public OASIS API, and no utility data of any kind. Method, results and stated limitations are in the attachment, Section 4. We should also be plain about scope: the analysis covers the PG&E service area only. Nothing in the method is specific to PG&E, and the same computation runs anywhere the CAISO settles a node, but we have not run it in the other service territories and do not claim the magnitudes carry across them.
We should be clear that this is a floor, not a ceiling. A PTO holds inputs no external party does — contingency and load-flow cases, shift factors, and planned outage and in-service schedules — and a disclosure produced with those inputs would be materially better than one produced without them. Our point is not that external analysis is sufficient. It is that the floor is already higher than nothing, and nothing is what the Straw Proposal currently offers a prospective flexible load.
3.
Please provide your organization’s comments on section C. Requirements for co-located arrangements.
a. Please provide comments on terminology.
b. Please provide comments on serving co-located loads.
c. Please provide comments on cost allocation for co-located loads.
d. Please provide any other comments on this topic.
a. Terminology
No comment.
b. Serving co-located loads
One finding bears on the assumption that a large load facing congestion can mitigate it with co-located generation. We overlaid hourly NASA POWER irradiance with day-ahead congestion prices at 44 PG&E settlement locations across 2024 and 2025.
Congestion concentrates in daylight hours, and more so at lower thresholds: 87% of congested node-hours fall between 08:00 and 16:59 local at a $10/MWh threshold, against 67% at the $50/MWh trigger used for the exposure figures elsewhere in these comments. We give both because the spread is itself informative. The lower threshold describes the diurnal shape across many more hours; the higher one describes the hours a load would actually be asked to stand down.
Mitigation varies roughly fourfold across nodes. At $10/MWh, a 100 MW array against a 100 MW load removes 11% to 45% of the annual congestion charge depending on the node; doubling the array with storage sized at the full load spans 64% to 98%, and half-load storage with the array unchanged spans 36% to 66%. At the $50/MWh trigger the same 100 MW array spans 0% to 44%. The low end of that range is not the interesting part: it sits at nodes whose entire annual congestion charge is well under the $182,000 median across the 44, where a percentage of very little is still very little. Nor is the relationship monotonic. Rio Oso carries the largest charge in the set and sits only tenth from the bottom on mitigation, so the size of a node's congestion charge does not by itself predict how much of it on-site generation will remove.
The ranking is counterintuitive. Figures below are on the $10/MWh basis except where the $50/MWh trigger is named. The node carrying the largest congestion charge in our sample, Rio Oso (RIOOSO_1_N033), is also the hardest of the 44 to mitigate: under the largest build we modeled it retains a greater share of its charge than any other node in the set, leaving $3.2M of a $9.0M annual charge in place. That ranking is the one robust result here, in that it holds at the $50/MWh trigger as well, where the same node carries a $5.9M charge. Everything else moves with the threshold: under solar alone Rio Oso ranks seventh worst at $10/MWh and tenth at $50/MWh, so it is the extreme case by construction and not the typical one. We give the pricing node identifier so each of these can be checked against your own record for that point.
Concretely, the CAISO should not permit a co-located arrangement to be credited with mitigating a large load's exposure on the basis of a generic assumption. By generic we mean any figure not derived from that node's own hourly congestion record and the hourly resource at its own coordinates: a fleet-average capacity factor, a regional irradiance figure, or a nameplate ratio would all fall on the wrong side of that line. We offer the definition so it can be adopted or amended rather than left to be settled later. Where co-located generation is offered as mitigation, the expected offset should be stated for that specific node and on an hourly basis, because that is the only resolution at which the answer differs between sites. A co-located framework should not assume a uniform capacity to self-mitigate. Two loads offering identical flexibility at nodes with identical annual curtailment hours can face residual exposures differing several-fold, and the party accepting the interruption right should know which case applies before it signs.
c. Cost allocation for co-located loads
No comment.
d. Any other comments on this topic
No comment.
4.
Please provide your organization’s comments on section D. New transmission services for flexible large loads.
a. Please provide comments on the Flexible Interim Load Interconnection (FILI) offering.
b. Please provide comments on the Flexible Load Interconnection – Permanent (FLIP) offering.
c. Please provide any other comments on this topic.
a. Flexible Interim Load Interconnection (FILI)
The Straw Proposal states, of FILI, that "CAISO declines to propose any kind of temporal or capacity cap on this interconnection service offering" (p. 38). Two paragraphs earlier, on the same page, it states that "To date, no stakeholder has requested that the CAISO develop non-firm transmission services. To the contrary, developers consistently express that they are only interested in acquiring firm service and would only agree to be flexible temporarily to interconnect before completion of long-lead network upgrades" (p. 38).
We read those two statements as cause and effect, not as two separate findings.
A large load financed on project debt cannot accept an obligation of unbounded duration and unknown frequency. Debt service reserve sizing, letter of credit terms and covenant structures are all built around a quantified view of downside: a lender needs some basis for how often, and for how long, revenue-generating operations might stop. An interruption right with no stated limit and no disclosed expectation gives a financing party nothing to size against, because nothing in the offer states how many hours a year the load is expected to stand down. The developer is not expressing a preference for firm service in the abstract. It is expressing the only position available to a project that has to clear underwriting.
Declining to cap the service and finding no demand for the service are not two separate results. They are the same result.
We would also note that the record is fuller than the Straw Proposal reflects. In comments filed February 25, 2026, five filers addressed the idea directly, and their positions differ enough that we would rather distinguish them than summarize. BAMx carried it as numbered recommendation 4, that the CAISO "should explore the concept of non-firm transmission service to large stand-alone or co-located load". American Clean Power "supports CAISO exploring with stakeholders a less firm or flexible transmission service product for large loads". The City and County of San Francisco, under its section 3, "supports the CAISO's exploration of non-firm or curtailable transmission service". Avantus went further, writing that "it makes sense to offer various service level options to large load customers including off-peak non-firm service". NextEra Energy Resources put it more tentatively, under its section v: it "sees merit in CAISO exploring potential new transmission solutions" of that kind.
We would not characterize all five as having requested the service, and we are not asking the CAISO to read them that way. Four support exploring it and one sees merit in doing so. That is still a materially different record from one in which the question has not been raised. There is a real distinction between supporting exploration of a service and formally requesting its development, and we are not suggesting the record was mischaracterized deliberately. We raise these filings because the difference between a record in which no stakeholder has requested this, and one in which several filers supported exploring it on terms yet to be defined, bears on whether the CAISO should prioritize this work. The filings are quoted in full in the attachment, Section 1.
b. Flexible Load Interconnection – Permanent (FLIP)
The Straw Proposal asks stakeholders to comment on which services to prioritize, "including whether options such as FLIP are not worth pursuing at this time" (p. 39).
We recommend retaining FLIP, and we recommend not offering it in its current form.
As described, FLIP asks a load to accept "terms of flexible interconnection service in perpetuity" (p. 38) in exchange for avoiding network upgrade funding and delay. A perpetual, uncapped, unquantified interruption right is not something a lender can finance, and we would expect FLIP to draw the same response the CAISO has already observed to non-firm service generally. The problem is not that developers are unwilling to be flexible. It is that no rational financing party accepts an unbounded obligation of unknown magnitude in exchange for a known and immediate benefit.
Paired with a quantified exposure disclosure, and optionally with a negotiated annual hour cap above which firm service or compensation applies, FLIP becomes a legible trade: a stated number of curtailment hours per year against avoided upgrade cost and years of schedule. That is a trade a developer can evaluate and a lender can price.
c. Any other comments on this topic
The disclosure should be hourly, not annual. An annual curtailment-hours figure is equally consistent with an exposure that on-site generation would largely offset and with one it would barely touch. Only the hourly shape separates them, and only the hourly shape lets a load price its own flexibility offer correctly.
5.
Please provide your organization’s comments on section E. Serving electrically proximate large loads.
No comment.
6.
Please provide your organization’s comments on the Operational Forecasting Requirements.
We support forecasting requirements. One observation on the reciprocal case.
The value of a forecasting obligation placed on the load depends partly on whether the load can anticipate when it will be asked to curtail. We have tested whether that is possible from public data alone. Across 44 nodes and 18 monthly forecasts, a month-ahead forecast of congested hours achieves 31% median absolute error against 65% for a seasonal-climatology benchmark, taking the median across those 18 months. It outperforms the benchmark at 38 of 44 sites, and the failure modes are published alongside the results.
We offer it as evidence that the quantity is forecastable to a useful degree from public inputs, and that a party holding contingency cases and outage schedules could do considerably better. Method and limitations are in the attachment, Section 4.
7.
Please provide your organization’s comments on the proposed Technical Requirements.
No comment on the technical requirements themselves. We note only that the Technical Requirements Straw Proposal of June 15, 2026 expressly excludes "broader planning, market participation, scheduling, or operational requirements" (p. 2), which is where the question of what a flexible load will actually be asked to do would otherwise sit.
8.
Please provide your organization’s comments on the Technical Requirements under development.
No comment.
9.
Please provide any additional comments on the straw proposal or Aug 19 meeting discussion.
Our comments are narrow and address a single issue: the Straw Proposal creates two flexible interconnection services without any mechanism by which a prospective large load can determine what accepting flexibility would actually cost it. We believe that omission, rather than a lack of developer appetite, explains the market response the CAISO reports, and we believe it is fixable now from data the CAISO already publishes.
The attached comment sets out five recommendations in full, with sources. Every quotation in it has been verified verbatim against the Straw Proposal of August 12, 2026, the Large Load Technical Requirements Straw Proposal of June 15, 2026, and the stakeholder comments of February 25, 2026.
KritiGrid would be glad to provide the underlying analysis, methodology and source code to the CAISO or to any PTO on request, and appreciates the opportunity to comment.
Pacific Gas and Electric Company
Submitted 09/02/2026, 04:35 pm
1.
Please provide your organization’s comments on section A. Transmission Service to eligible customers.
a. Please provide comments on the definition of large loads.
b. Please provide comments on the large load application process and interconnection study procedures.
c. Please provide comments on the large load operational requirements.
d. Please provide any other comments on this topic
Introduction
Pacific Gas and Electric Company (“PG&E”) respectfully submits these comments on the California Independent System Operator Corporation’s (“CAISO”) Large Load Considerations Straw Proposal, issued August 12, 2026 (the “CAISO Straw Proposal”). PG&E submits these comments as both a Participating Transmission Owner (“PTO”) named as a respondent in the June 18, 2026 Order to Show Cause[1] issued by the Federal Energy Regulatory Commission (“FERC” or “Commission”) and a Utility Distribution Company (“UDC”) that serves as the primary interface for Large Loads seeking to interconnect within its PTO Service Territory.[2]
PG&E is one of the three Original Participating Transmission Owners (“Original PTOs”) that transferred Operational Control of their transmission facilities to the CAISO while retaining ownership, physical operation, and maintenance responsibilities.[3] These Original PTOs, along with other Load-Serving Entity PTOs (“LSE-PTOs”) occupy a unique position within the CAISO market structure.
As Utility Distribution Companies (“UDCs”), the Original PTOs serve native load retail customers within their service territories through their own physical distribution facilities.[4] This retail service relationship is governed by tariffs approved by the California Public Utilities Commission (“CPUC”). The Original PTOs bear a continuing obligation to serve these customers pursuant to state law.
The LSE-PTOs also serve Eligible Customers that seek connection to the grid by providing transmission interconnection service. The Original PTOs recover their just and reasonable transmission costs through Transmission Revenue Requirements approved by the Federal Energy Regulatory Commission ("FERC" or “Commission”). These costs are recovered from Eligible Customers through the Transmission Access Charge ("TAC") under the CAISO Tariff.[5] "Eligible Customer" means (i) any utility, federal power marketing agency, or any person generating Energy for sale or resale, and (ii) any retail customer taking unbundled transmission service pursuant to a state retail access program.[6] In recognition of the multiple roles and concurrent obligations of this subset of PTOs, these comments refer to “LSE-PTOs” to mean PTOs that are also Load-Serving Entities.
The CAISO’s transmission service model differs from the traditional Order No. 888 framework in that there is no formal application process for transmission service, and Eligible Customers do not reserve transmission capacity in advance.[7] Instead, Scheduling Coordinators (including Eligible Customers certified as Scheduling Coordinators) submit bids or self-schedules for supply and demand into the CAISO day-ahead and real-time markets, with equal access to all available transmission capacity each day.[8] If available transmission capacity is insufficient, the CAISO curtails schedules based on tariff-defined scheduling priorities.[9]
PG&E’s load interconnection service is coordinated with the CAISO, which provides Market Access and Generation Interconnection service to wholesale customers. This coordinated framework supports the respective tariff responsibilities of the PTOs and the CAISO under the Transmission Control Agreement and ensures that interconnections are studied, planned, and implemented in a manner consistent with transmission reliability requirements and long-term transmission plans.
Applicants seeking wholesale generation interconnection to the CAISO-controlled grid submit their requests to the CAISO, while applicants seeking wholesale load interconnection to the CAISO-controlled grid submit their requests to the relevant PTO. Consistent with the regional framework, retail customers must apply for transmission interconnection service through an Eligible Customer and cannot directly apply for transmission interconnection service.[10] The CAISO reviews PTO interconnection study results through a concurrence process to ensure alignment with its Transmission Planning Process (“TPP”), and it approves network upgrades affecting the CAISO Controlled Grid.[11]
Non-LSE PTOs bear different obligations within the CAISO framework. These PTOs generally include entities that joined the CAISO after its formation by constructing transmission facilities selected through the FERC Order No. 1000 competitive solicitation process.[12] These entities do not have PTO Service Territories and do not have an obligation to serve retail load.[13] They are eligible for cost recovery through their own TO Tariffs, but they do not perform the same interconnection study and UDC functions as the original PTOs. The distinction is significant because PTOs with PTO Service Territories bear primary responsibility for processing Large Load applications, conducting interconnection studies, coordinating with affected systems, and managing the cost allocation and recovery processes that prevent cost shifting.
PG&E broadly supports the Straw Proposal and commends the CAISO for advancing a framework that responds to the Commission’s directives while maintaining the established division of responsibilities between the CAISO and the PTOs. PG&E recognizes the urgent need for solutions that enable Large Load interconnection while maintaining grid affordability and reliability. PG&E supports the CAISO’s approach of preserving the existing allocation of interconnection and study responsibilities—under which PTOs continue to process applications for and study new Large Loads, and the CAISO reviews those studies for consistency with its transmission planning activities—which has proven efficient and effective. PG&E’s support, however, is qualified in several key respects, and PG&E offers targeted recommendations throughout these comments, including regarding the definition of “Large Load” and the sequencing of new flexible interconnection services. PG&E offers these recommendations toward ensuring the Commission’s cost-shifting and reliability concerns are adequately addressed. In addition to the targeted recommendations below, PG&E believes the CAISO should provide critical, region-specific context up front. PG&E therefore recommends that the CAISO include in its response to the OSC a background section explaining the unique CAISO transmission service model and existing CAISO terminology, which differ from other regional transmission operator (“RTO”) and independent system operator (“ISO”) models.
PG&E appreciates the opportunity to provide comments on this preliminary proposal detailed below, and also provides the following general comments:
- PG&E’s comments do not address whether the proposed changes are properly placed in the CAISO Tariff or elsewhere, but in some instances, it is not clear where the CAISO intends to incorporate or implement its proposals. PG&E recommends that the CAISO clarify where it plans to place these changes.
- PG&E believes that it is appropriate that the CAISO has not proposed market operation revisions in this initial draft, but such revisions may be necessary in the long term.
- The current framework wherein a retail customer must take service through an Eligible Customer is consistent with FERC Order No. 888, and, as such, PG&E agrees with the CAISO’s general approach to the Straw Proposal in that it does not contemplate providing a mechanism for End-Use Customers to directly access transmission service, including load interconnections.
- Given the differences in roles and responsibilities described above, PG&E emphasizes the importance of establishing consistent expectations for the study and interconnection of Large Loads, through the CAISO’s Tariff and the PTOs’ respective tariffs.
The remainder of PG&E’s comments specifically address and follow the structure of the Straw Proposal and the CAISO’s stakeholder comment template. PG&E addresses, in turn:
- Section A — Transmission Service to Eligible Customers on Behalf of Large Loads, including the definition of “Large Load,” the application process and interconnection study procedures, ongoing operational requirements, and Large Load service agreements;
- Section B — the framework to prevent cost shifting, including roles and responsibilities and data transparency;
- Section C — requirements for co-located arrangements, including terminology, the study of co-located loads, and cost allocation;
- Section D — new transmission services for flexible Large Loads, including the Flexible Interim Load Interconnection (FILI) and Flexible Load Interconnection–Permanent (FLIP) offerings; and
- Section E — serving electrically proximate Large Loads.
PG&E then provides comments on operational forecasting requirements, the proposed technical requirements, the technical requirements currently under development, and such additional matters as may bear on the Straw Proposal and the August 19, 2026 stakeholder meeting.
Section A
In Section A, the CAISO responds to the first category of concerns in the Order to Show Cause, which addresses the application process, study procedures, and ongoing operational requirements that apply to Eligible Customers seeking transmission service on behalf of Large Loads.[14] The CAISO proposes to preserve the existing division of responsibilities—under which the PTOs process and study Large Load interconnections and the CAISO reviews those studies for consistency with its transmission planning—while adding targeted tariff clarifications, new information requirements, and operational requirements.[15] In addition to the following general comments, PG&E addresses each of the CAISO’s proposals below in the order the CAISO presents them.
Before addressing the CAISO’s specific proposals, PG&E emphasizes the importance of distinguishing among the various types of entities that participate in the CAISO transmission system, each with different responsibilities for processing and studying Large Load interconnections.
a. Please provide comments on the definition of large loads.
The CAISO proposes to add a definition of “Large Load” to its tariff, while cautioning that a definition may be premature because NERC is concurrently developing potentially overlapping standards for computational loads.[16] The CAISO’s proposed definition modifies the Commission’s suggested definition by omitting a description of the type of load, an interconnection voltage threshold, and the exclusion of co-location arrangements. The CAISO also declines to adopt additional rules to deter de-aggregation or gaming.[17] The CAISO focuses this initiative on transmission-connected Large Loads.[18]
Specifically, the CAISO Straw Proposal defines Large Load as “[a]n End User located at a single site interconnecting to the CAISO Controlled Grid, and that has a peak load of 50 MW or greater.”
This definition would include any Eligible Customer with a Point of Interconnection on the CAISO-Controlled Grid that serves a customer at a single site with a peak load of at least 50 MW. PG&E supports the CAISO’s effort to define a distinct category of Large Loads and believes that the proposed definition requires refinement to capture all load that will have a material impact on the CAISO-Controlled Grid.
PG&E understands that CAISO’s intended interpretation of this definition would be that the service voltage at the customer site would not be a defining criterion; rather, an Eligible Customer would be subject to the requirements adopted in response to the OSC for the portion of its Gross Load at the POI that is attributable to a single-site End User with peak load above the threshold 50 MW.
However, PG&E believes that the phrase “interconnecting to the CAISO Controlled Grid” is ambiguous as written because End Users do not connect directly to CAISO-controlled facilities, but rather are served by Eligible Customers via points of interconnection (POIs) with the CAISO controlled grid.[19] To ensure uniform application, PG&E recommends that the final proposed definition explicitly include all loads above the MW threshold that affect the CAISO transmission system, i.e., loads above the MW threshold served by an Eligible Customer via a POI on the CAISO Controlled Grid. Clarity in the application of this definition would also avoid leaving the door open to strategic site selection by developers attempting to avoid the requirements imposed in response to the OSC. Defining Large Load too narrowly or ambiguously could exclude Large Loads with meaningful operational impacts on the CAISO grid and could shift costs to other customers, undermining the Commission’s cost-shifting and reliability objectives.
PG&E also recommends that the CAISO utilize a 20-MW peak-load threshold. This threshold reflects PG&E’s operational experience that Large Loads affecting the network transmission system are often smaller than 50 MW, and a 20-MW threshold would better capture transmission system impacts from smaller, yet still meaningful, loads seeking to interconnect. A 20-MW threshold aligns with NERC’s assessment that loads as small as 20 MW can present material grid impacts. In its Level 3 Alert issued May 4, 2026, NERC indicated it was working to register any “Computational Load Entity,” defined to include loads that are 20 MW or greater, connected at 60 kV or higher, and host more than 1 MW of load from information technology equipment. The Commission has also expressed concern that providing transmission service to Eligible Customers on behalf of Large Loads “may be more complex and could raise greater reliability concerns for the transmission system” due to the size, concentration, and unique load profiles of such customers.
Therefore, PG&E proposes to define “Large Load” to mean: “An End User located at a single site that has a peak load of 20 MW or greater and is served by an Eligible Customer through a point of interconnection on the CAISO Controlled Grid.”
PG&E believes that this proposed definition provides clarity where the CAISO-proposed definition may otherwise vary in application depending on how each PTO’s distribution system is configured. As such, PG&E believes that this definition will promote the Commission’s objective of ensuring “clarity and consistency” across the CAISO footprint.
PG&E also recommends that the CAISO consider a 50 kV threshold at the End-User’s retail Point of Interconnection to the UDC as an additional measure to distinguish between customers that will have a high impact on the CAISO grid. PG&E notes that SPP establishes the voltage threshold at the POI of the End Customer under the recently approved definition of High Impact Large Load (“HILL”) in the SPP tariff.[20] Voltage, like load volume, customer class, or single-site status, represents one criterion for distinguishing between load that does or does not have a material impact on the bulk system. To ensure consistent application across the CAISO balancing authority, any voltage threshold should be set uniformly.
b. Please provide comments on the large load application process and interconnection study procedures.
In its proposal for a Large Load application process and interconnection study procedures, the CAISO restates its view that the PTOs currently conduct the existing load interconnection process efficiently and effectively.[21] The CAISO proposes enhanced coordination, data sharing, and alignment of PTO application processes and study timelines, including study procedures completed within 60 to 90 days.[22] The CAISO proposes to address alternative transmission technologies through annual Transmission Plan reporting rather than case-by-case justification, to clarify the purpose and approach to the concurrence process in the context of Large Loads, and to specify when it may decline to concur in PTO study results.[23] The CAISO defers to the PTOs to revise their TO tariffs to deter speculative or duplicative requests.[24]
The costs of network upgrades identified through the PTO load interconnection process—as distinct from upgrades approved through the TPP—are currently directly assigned to the Eligible Customer rather than socialized through the TAC.[25]
Application Process
As discussed above, the CAISO region is largely comprised of the local electric distribution service territories of several PTOs including PG&E, Southern California Edison Company, San Diego Gas & Electric Company, and Valley Electric Association, Inc. These PTOs have unique responsibilities, including with respect to the local Transmission Access Charge collected within each PTO’s Service Territory.
Given these distinctions, PG&E believes the Large Load interconnection process should be administered by each PTO based on the distribution service territory where the Large Load is located. In practice, this means that the PTO within its PTO Service Territory would typically handle most Large Load interconnection requirements, including offering flexible interconnection service, executing cost recovery agreements, and processing applications.[26] While PG&E seeks a process that creates equitable expectations and outcomes across the CAISO service regions, PG&E acknowledges that implementation details may vary across PTO Service Territories and whether a PTO is also a UDC. Non-UDC PTOs would not process retail Large Load interconnections and would continue to offer traditional wholesale load interconnection service to Eligible Customers pursuant to Section 10 of their respective TO Tariffs.
PG&E supports an application process under which the relevant LSE-PTO would receive the application for transmission interconnection service for Points of Interconnection within its PTO Service Territory. PG&E expects that the application process for Eligible Customers under TO Tariffs would be consistent with the application process for End Use Customers through the CPUC’s Rule 30 process, so that wholesale and retail customers would effectively undergo the same application process. PG&E supports TO Tariff revisions that identify the technical information required from Large Loads, and encourages coordination with CAISO and across the PTOs to develop consistent timelines to meet the sixty to ninety-day timeline proposed. The CAISO Straw Proposal recognizes that the existing interconnection process is conducted efficiently and effectively by the PTOs for their respective service territories, and PG&E agrees that the task should remain with the PTOs. New CAISO and TO Tariff provisions will provide enhanced coordination and reporting to provide greater visibility for the CAISO to plan for new Large Loads and maintain reliability once the load is interconnected. As with other provisions, PG&E believes that the technical information should be uniform across PTO Service Territories and in non-LSE and LSE-PTO Tariffs to facilitate this enhanced coordination and reporting.
Speculative or duplicative requests would be addressed through each PTO’s application process. The PTOs will propose appropriate criteria (e.g., financial commitments and data submissions) to reduce and/or be able to more readily identify duplicate Large Load interconnection requests.
New TO Tariff amendments relating to Large Loads will not supersede or replace Section 10 of the TO Tariff, which will continue to apply to wholesale loads. That said, if a Large Load is interconnecting to a wholesale customer that lacks transmission facilities, but plans to build transmission facilities to interconnect a Large Load, information about the Large Load must be submitted to the appropriate PTO.
PG&E will work with non-LSE PTOs in its PTO Service Territory to address responsibilities for applications for interconnections of Large Loads.
Study Process
PG&E expects the vast majority of Large Loads to be electrically dependent and require coordinated study in a cluster process. PG&E agrees that the CAISO Tariff should establish timing deadlines for the Large Load study process. A Large Load Transmission Interconnection Study Process will be set forth in TO Tariff amendments and, as discussed below, the CAISO will continue to conduct the existing TPP, which evaluates system-level impacts. PG&E supports allocating responsibility to the PTOs to amend their TO Tariffs to address issues such as study timelines; study procedures; types of network upgrades considered; methods to determine required network upgrades; collection of information required by the CAISO to provide transmission service to a Large Load; and alternative transmission technologies.
PG&E expects that, consistent with the Commission’s and CAISO’s recommendations, its revisions to the study process will include a Large Load Interconnection Study Agreement. The agreement structure may vary depending on whether the Large Load seeks flexible interconnection service. To accommodate both firm and non-firm service requests, PG&E is considering two structural options: (1) a single pro forma Large Load Interconnection Study Agreement with a separate optional Flexible Interconnection Service Addendum that specifies the conditions and service applicable during the period that network upgrades are being constructed, which would automatically convert to firm service upon completion; or (2) a distinct pro forma Flexible Interconnection Study Agreement for Large Loads seeking conditional service.
PG&E believes that PTOs should be permitted to perform studies sequentially or in clusters, based on circumstances such as electrical interdependence or merit, but that those options should be clearly defined and tied to timelines that align across the TO and the CAISO tariffs. The study process should address other affected transmission systems and, if merited by the facts, PG&E supports avenues for the PTOs to conduct joint studies and supports efforts by the PTOs to enhance coordination and visibility between the CAISO and PTOs regarding study results as compared to non-Large Loads, as well as coordinating affected system studies with non-CAISO entities as may be needed. PG&E anticipates that the PTOs will identify ways to improve alignment on load interconnection with the CAISO planning processes and will support and cooperate in efforts to do so. PG&E shares in the CAISO’s vision of clarifying the CAISO concurrence process, under which the CAISO reviews load interconnections that cause the need for additional facilities and expects that these clarifications may need to be incorporated in both the TO and the CAISO tariffs.
For resources with Co-Located Large Load, the CAISO proposes that the Large Load be studied by the PTOs and that the CAISO coordinate its Cluster Study process for wholesale generation interconnection with the relevant PTO’s study of the co-located Large Load transmission interconnection. This split approach is taken due to the PTOs’ and the CAISO’s respective legal obligations to interconnect retail load and wholesale generation. PG&E expects that tariff revisions will provide for the exchange of necessary information between the CAISO and PTOs to serve co-located customers.
PG&E generally supports the CAISO’s proposed framework for Large Load interconnection studies and offers the following observations:
- The CAISO appropriately preserves the existing allocation of study responsibilities, under which PTOs perform the bulk of load interconnection studies. This structure has proven efficient and effective, and PG&E agrees it should continue with appropriate enhancements for coordination and visibility.
- A key distinction between load and generation is the utility’s obligation to serve load. Unlike generation—which has no inherent right to interconnect—load carries with it a utility obligation to serve retail customers. This distinction supports maintaining the PTO-led study process for Large Load interconnections and counsels in favor of study timelines that can accommodate the load-serving obligation.
- PG&E supports the CAISO’s clarification that the concurrence process is the appropriate mechanism for ensuring that network upgrades identified through the PTO-led load interconnection study process are integrated with the TPP.[27] PG&E agrees that the TPP remains the appropriate venue for approving broader network upgrades that affect the CAISO-Controlled Grid.
- However, given the utility’s obligation to serve load and FERC’s expectation of a 60-90-day study timeline,[28] the existing annual TPP cycle may not always align with the needs of Large Load interconnection requests that arise after development of the demand forecast. PG&E recommends that the CAISO develop an off-cycle process for area-wide network upgrades triggered by Large Load interconnections that cannot await the next annual TPP. Such an off-cycle process could be addressed either as an exception to the TPP or as a modification of the approved Transmission Plan. Either approach would allow PTOs to proceed with necessary network upgrades to serve Large Loads on a timeline consistent with the load-serving obligation while preserving the CAISO oversight through the concurrence process.
c. Please provide comments on the large load operational requirements.
The CAISO agrees that the ongoing operational requirements the Commission identifies are necessary to maintain reliability as Large Loads interconnect, and it anticipates that the PTOs will require monitoring, control, and protection systems—potentially including automated load reduction and the ability for the CAISO to remotely disconnect a Large Load.[29] To support this oversight, the CAISO proposes tariff provisions enabling the exchange of Large Load interconnection and operating data between the CAISO and the PTOs, and between the CAISO and the LSEs’ Scheduling Coordinators.[30] The CAISO addresses the specific forecasting and technical requirements in the portions of the Straw Proposal that PG&E discusses in response to questions 6 through 8 below.
PG&E helped develop the various technical requirements proposed by the CAISO and supports their implementation here. The application process would require significant technical information, as well as information regarding intended operations, and would be used to develop an agreement (what FERC calls the transmission service agreement) addressing Large Load operations—discussed in subsection (d), below. The PTOs will require monitoring, control, or protection systems as needed for operational and reliability purposes. Depending on the service type requested, a Large Load may need automated load reduction equipment and/or be subject to the CAISO’s request that a PTO physically disconnect the Large Load.
PTOs will need to develop data transfer protocols in connection with the operational requirements to provide data to the CAISO, which likely would require consent from the Scheduling Coordinator, the UDC, and the Large Load. Data systems will have to be created to allow Large Loads to report their schedule and outages on an individual basis, much like Generators report outages.
Where a PTO is not the same legal entity as the Scheduling Coordinator for a Large Load, operational data for the Large Load will need to be submitted to the PTO. The PTO will need such data both to support any flexible interconnection products offered as well as to coordinate with the CAISO on reliability issues related to all Large Loads.
d. Please provide any other comments on this topic.
The CAISO agrees with the Commission that the existing tariffs lack pro forma provisions memorializing the technical and operational terms for Large Loads, and the CAISO states that it expects the PTOs to develop a consistent pro forma agreement.[31] The CAISO indicates that it need not always be a signatory: a two-party agreement between the PTO and the developer may suffice for firm service involving simple network upgrades, while non-firm service and co-located Large Loads with exporting generation may require the CAISO to join the agreement, including through an instrument that bridges the pro forma Large Generator Interconnection Agreement or a non-conforming LGIA.[32]
Large Load Agreement(s)
PG&E supports developing one or more TO Tariff pro forma agreements to address (1) Large Load operations, including data sharing requirements (as discussed in subsection c above), and (2) cost-shifting prevention. For simplicity, PG&E refers to a single “Pro Forma Large Load Interconnection Service Agreement” that would address operations and cost-shifting for firm service.[33] For Large Loads seeking conditional service (i.e., flexible interconnection service), PG&E proposes developing an optional Flexible Interconnection Service Addendum to the Pro Forma Large Load Interconnection Service Agreement that specifies the terms of conditional service, including curtailment conditions, operational requirements during the interim period, and automatic transition to firm service upon completion of network upgrades—as further discussed in Section 4 below.
PG&E confirms that it will strive to have consistent Pro Forma Agreements with the other PTOs.
[1] California Indep. Sys. Operator Corp., et al., 195 FERC ¶ 61,214 (2026) (“OSC”).
[2] Capitalized terms not otherwise defined in these comments have the meaning assigned to them in the California Independent System Operator Corporation Fifth Replacement FERC Electric Tariff.
[3] See Amended and Restated Transmission Control Agreement (“TCA”) §§ 4.1, 6.1.
[4] See CAISO Tariff § 4.
[5] See CAISO Tariff § 26.1.
[6] CAISO Tariff, App. A.
[7] See OSC at P 19.
[8] See CAISO Tariff § 4.5.3 (Responsibilities of a Scheduling Coordinator).
[9] OSC at P 20.
[10] PG&E notes that service to bundled retail customers within the PTO Service Territory is governed by the retail tariff.
[11] CAISO Tariff §§ 4.3.1, 24.
[12] See id. § 24.5.
[13] See CAISO Straw Proposal at 17.
[14] CAISO Straw Proposal at 7–8; OSC at P 3.
[15] CAISO Straw Proposal at 8.
[16] CAISO Straw Proposal at 8–9.
[17] CAISO Straw Proposal at 9–10; OSC at P 57.
[18] CAISO Straw Proposal at 10.
[19] Because PG&E is not aware of a situation where an End User could directly connect to a CAISO-controlled facility, a literal interpretation of “interconnecting to the CAISO Controlled Grid” could preclude any End User from being considered a Large Load.
[20] See OSC at P 15 (citing Sw. Power Pool, Inc., 194 FERC ¶ 61,031 at PP 61, 64 (2026) (“SPP HILL Order”)); SPP, Open Access Transmission Tariff, Sixth Revised Vol. No. 1, pt. I, § 1 (Definitions H) (1.0.0).
[21] CAISO Straw Proposal at 11.
[22] CAISO Straw Proposal at 10–12; OSC at PP 58–62.
[23] CAISO Straw Proposal at 12–17; OSC at PP 51–55.
[24] CAISO Straw Proposal at 17.
[25] See OSC at P 56.
[26] PG&E notes that, in some circumstances, an LSE-PTO may request transmission interconnection service on behalf of a retail customer (End-User) that requires the UDC to request service from another PTO.
[27] CAISO Straw Proposal at 16.
[28] See OSC at P 62.
[29] CAISO Straw Proposal at 17–21; OSC at P 63.
[30] CAISO Straw Proposal at 21-22.
[31] CAISO Straw Proposal at 24; OSC at P 64.
[32] CAISO Straw Proposal at 24.
[33] Although FERC refers to these types of agreements as “transmission service agreements,” the Pro Forma Agreement would address transmission interconnection service, not the CAISO-provided transmission service that Eligible Customers access through Scheduling Coordinators under the CAISO Tariff.
2.
Please provide your organization’s comments on section B. Framework to prevent cost-shifting.
a. Please provide comments on roles and responsibilities to prevent cost shifting.
b. Please provide comments on data transparency.
c. Please provide any other comments on this topic.
In Section B, the CAISO addresses the framework to prevent cost shifting among transmission customers, responding to the Commission’s objectives of improved transparency regarding the assignment of network upgrade costs and the development of a pro forma cost recovery agreement.[1] Following general comments on the relationship between roles and responsibilities and cost recovery in the CAISO region, PG&E addresses the CAISO’s proposals on roles and responsibilities and on data transparency in turn, below.
As discussed above, PG&E recommends that the CAISO emphasize the differences in roles and responsibilities between entities participating in the CAISO. These differences bear on cost recovery mechanisms in the CAISO. The Transmission Access Charge (“TAC”) provides for cost recovery associated with the development, operation, and maintenance of transmission facilities used to provide transmission service through the CAISO.[2] Unlike in some other RTOs and ISOs, where transmission charges may be assessed based on peak demand or point-to-point reservations, the CAISO assesses the TAC on a volumetric basis against UDCs[3] based on Gross Load served within each PTO Service Territory—meaning total end-user demand accounting for losses and excess behind-the-meter production.[4] This means transmission costs are allocated based on total delivered electricity, rather than on usage of specific transmission facilities or peak demand figures.[5]
In contrast to the LSE-PTOs, other LSEs in the PTOs’ retail service areas—Community Choice Aggregators and Direct Access providers—do not own or operate transmission facilities subject to the CAISO’s operational control; instead, these LSEs procure wholesale power and inform the LSE-PTOs how much to bill each of their retail customers for power. The UDCs then bill these LSEs’ retail customers pass-through power charges and also bill them for services the LSE-PTOs provide, including transmission and distribution, as well as all other CPUC-authorized charges.[6] Non-FERC-regulated UDCs and MSS Operators that pay the TAC (e.g., public power utilities that are in the CAISO’s Balancing Authority Area), some of which are PTOs and some of which are not, are also LSEs, and they include their transmission costs in their bundled rates that allow them to recover their share of the TAC. Investor-owned and public power utilities that are not UDCs or MSS Operators because they are outside the CAISO Balancing Authority Area would pay for Wheeling if they take transmission service from the CAISO.
a. Please provide comments on roles and responsibilities to prevent cost shifting.
The CAISO states that it agrees with the Commission that the PTOs should lead development of a pro forma cost recovery agreement and establish cost allocation rules in their own tariffs rather than the CAISO tariff, given the PTOs’ direct relationship with retail ratepayers, their cost allocation expertise, and their ownership of the network upgrades.[7] The CAISO declines to impose a top-down cost allocation solution and concludes that upfront contributions by developers and existing adjustment mechanisms that can apply against the transmission revenue requirement provide the kinds of mechanisms mentioned by the Commission in the Order to Show Cause, such that the CAISO does not see a reason to change the Transmission Access Charge at this time.[8]
PG&E is supportive of the CAISO’s proposal, with the understanding that “cost recovery agreement,” as used by the CAISO (and FERC), refers to an agreement that protects other customers from cost shifting if the Large Load departs, downsizes or otherwise fails to contribute the level of revenues anticipated. This protection is provided by requiring financial assurances or other monetary protections.
The Commission focuses on mechanisms to prevent cost-shifting, with a focus on cost recovery, i.e., the mechanisms by which the PTO collects or secures funds to cover costs. Those mechanisms may include upfront payments, financial security, minimum annual revenue guarantees, and exit fees, all of which can ensure that the responsible party contributes adequate revenue and does not leave other transmission customers to bear greater costs. PG&E notes that this concept of “cost recovery” is distinct from “cost responsibility,” which focuses on which entity is ultimately responsible for bearing the costs associated with Large Load interconnection and “cost allocation,” which focuses on how costs incurred in providing transmission service are distributed (allocated) across customers and recovered through rate mechanisms like the Transmission Access Charge. These distinctions are important because the OSC focuses primarily on cost recovery mechanisms to prevent cost shifting, while leaving the existing TAC cost allocation methodology in place.[9]
Consistent with the Order to Show Cause, PG&E acknowledges that the PTO-LSEs will need to develop a pro forma cost recovery agreement to prevent cost shifting among transmission customers.[10] As discussed above with respect to PTO roles and responsibilities, the LSE PTOs serve as both UDCs and LSEs within their PTO Service Territories, giving them direct relationships with retail customers and expertise in cost allocation, rate impacts, and cost recovery matters. PG&E believes that the CAISO has appropriately recognized that the PTOs should lead the development of this agreement because these PTOs are responsible for recovering transmission costs from End-Use Customers within their PTO Service Territories, which is outside the scope of the CAISO’s transmission planning and market administration functions.[11]
PG&E supports the division of responsibilities relating to preventing cost shifts, particularly because the TAC methodology is not being changed. This approach should result in the PTOs drafting consistent relevant Pro Forma Agreements addressing cost issues.
b. Please provide comments on data transparency.
The CAISO states that it agrees with the Commission that cost data should be transparent and available on the CAISO website in a searchable format and the CAISO proposes to use or enhance its per-unit cost guides currently used for the generator interconnection study process, to clarify in the Transmission Planning Process where network upgrades accommodate general load growth versus Large Load interconnections, and to publicly post aggregate Large Load additions by transmission pricing zone, planned network upgrades, and associated cost estimates.[12] The CAISO would memorialize these transparency requirements in its tariff and encourages the PTOs to adopt Large Load queue spreadsheets.[13]
PG&E is generally supportive of the CAISO’s proposal. The PTOs will have to support the CAISO in its posting requirements and PG&E recognizes that the PTOs and/or UDCs will need to provide data in a format acceptable to the CAISO. PG&E expects that the transparency the CAISO contemplates will be similar to the transparency provided for in the generator interconnection queue process, and that it will remain consistent with California law. UDCs may need to require Large Load customer consent to pass information on to the CAISO.
c. Please provide any other comments on this topic.
PG&E does not have additional comments at this time.
[1] CAISO Straw Proposal at 25–28; OSC at P 65.
[2] See OSC at P 24.
[3] Under the CAISO Tariff, UDCs include Metered Subsystem (“MSS”) Operators that own and provide service over Distribution Facilities. PG&E notes that some entities that access load may be MSS Operators, but not UDCs, but would still ultimately be charged on a Gross Load basis.
[4] Id.; see also CAISO, Large Load Considerations Straw Proposal at 35 (Aug. 12, 2026).
[5] See id. (“[T]he CAISO would allocate costs to each large load with behind-the-meter generation to the extent the large load used the transmission system, as reflected by its metered load.”)
[6] See e.g., Pacific Gas and Electric Company, “Community Choice Aggregation (CCA),” available at https://www.pge.com/en/account/alternate-energy-providers/community-choice-aggregation.html.
[7] CAISO Straw Proposal at 25–26; OSC at PP 65–66.
[8] CAISO Straw Proposal at 26.
[9] See OSC at PP 76-84.
[10] See OSC at PP 65-66.
[11] CAISO Straw Proposal at 25–26.
[12] CAISO Straw Proposal at 26–27; OSC at PP 46, 72, 75.
[13] CAISO Straw Proposal at 27.
3.
Please provide your organization’s comments on section C. Requirements for co-located arrangements.
a. Please provide comments on terminology.
b. Please provide comments on serving co-located loads.
c. Please provide comments on cost allocation for co-located loads.
d. Please provide any other comments on this topic.
In Section C, the CAISO addresses co-location arrangements and load served by behind-the-meter generation, framing co-location principally as a study-process matter that preserves the existing jurisdictional boundaries between the CAISO and the PTOs.[1] PG&E addresses the CAISO’s proposals on terminology, the study of co-located loads, and cost allocation below, in turn.
a. Please provide comments on terminology.
The CAISO states that it generally agrees with the Commission’s definitions of “co-located load” and “behind-the-meter generation” but would exclude station power load and the generation that exclusively serves it.[2] The CAISO declines to create formal tariff definitions of these terms, reasoning that both already carry plain meanings and that “behind-the-meter” already appears throughout its tariff, and it indicates that it may issue clarifications in its business practice manuals if needed.[3]
PG&E agrees with the CAISO’s assessment that there is a general understanding within the CAISO of the meaning of “co-located load.” PG&E encourages the CAISO to develop a definition that would capture the existing breadth of arrangement to avoid future ambiguities that may arise as technologies and markets evolve. The Commission may also disagree with the approach of using a business practice manual, rather than the tariff, to define a term that the Commission has signaled as very salient.
b. Please provide comments on serving co-located loads.
The CAISO proposes to clarify how co-located Large Loads and generation may interconnect to and operate within the CAISO-controlled grid. The CAISO proposes to clarify in its tariff that configurations that do not export to the grid—such as backup generation and non-exporting behind-the-meter generation—would continue to proceed under PTO or CPUC-jurisdictional retail tariffs, such as Electric Rule 21, without a CAISO resource interconnection request, while co-located generation that may export would require a CAISO study under the Resource Interconnection Standards, with results reflecting the combined impact of the load and generation at the developer’s requested capacity.[4] The CAISO also proposes additional operational information requirements for co-located resources and proposes to bar adding or removing a Large Load once a cluster study is underway.[5]
Existing Co-Located Loads and Existing Generators
PG&E is generally supportive of efforts to facilitate co-location service. PG&E believes that the CAISO’s framing of co-location as fundamentally a study process issue is appropriate and consistent with the existing division of responsibilities between the CAISO and the PTOs. Under the current framework, the PTOs continue to govern and study all load interconnection requests pursuant to their tariffs, while the CAISO governs and studies wholesale generation interconnection requests.[6] For co-located configurations where generation may export to the grid, the CAISO’s cluster study process will evaluate the combined impacts of the load and generation together, ensuring that interconnection studies reflect the customer’s requested mode of operation and type of service.[7] This approach preserves the existing allocation of study responsibilities while enhancing coordination between the CAISO and PTO studies to produce consistent results.
California’s regulatory structure differs materially from other RTO/ISO footprints in ways that affect how co-location arrangements operate in practice. Under California law, subject to certain narrow exceptions, unregulated private generators may not serve third-party retail load directly.[8] This means that, unlike in PJM and other regions where a generator interconnection customer may serve co-located load behind the meter without using transmission or distribution facilities, in CAISO’s footprint grid-connected co-located loads and generation must still receive retail service from their load-serving entity and are governed by state-jurisdictional generator interconnection tariffs such as the CPUC’s Electric Rule 21.[9] The practical effect of this regulatory structure is that co-location arrangements in California will typically require some form of interconnection with the CAISO-controlled grid, even where the load is primarily served by on-site generation.
Because of these state-jurisdictional constraints, PG&E supports the CAISO’s proposed approach to limiting the CAISO’s role with respect to co-located loads to the study process and FERC-jurisdictional charges. The CAISO’s proposed tariff clarifications appropriately focus on (1) when a CAISO generator interconnection study is required (i.e., where co-located generation may export to the grid), (2) coordination between the CAISO and PTO studies to produce combined study results, and (3) the appropriate assessment of FERC-jurisdictional charges such as regulation and black start services on a gross load basis.[10] PG&E believes that this approach adheres to the existing jurisdictional boundaries while ensuring that the CAISO has the visibility and study coordination necessary to maintain system reliability.
PG&E supports the CAISO position that even with Co-Located Large Load, the PTOs will continue to perform load studies and share results with the CAISO, ensuring a cooperative approach with regard to identifying Network Upgrades.
PG&E seeks clarification on whether a Large Load seeking to be studied with a generating facility in the CAISO cluster study process must first complete the PTO study process prior to submitting an interconnection request to the CAISO queue. PG&E recommends that the two studies be structured to run concurrently whenever practical. Additionally, the straw proposal states that a Large Load that has been studied with a generating facility as part of the cluster study process may not be subsequently removed as a modification. PG&E requests clarification regarding the scope of this restriction. Specifically, PG&E seeks confirmation as to whether modifications to the Large Load that result in an increase in the co-located facility’s net MW export to the CAISO-controlled grid would also be prohibited or otherwise subject to modification restrictions.
c. Please provide comments on cost allocation for co-located loads.
The CAISO addresses cost allocation for co-located loads in three respects. It proposes to require the PTOs to sub-meter each co-located Large Load independent of any onsite generation so that regulation and black start services are assessed on a gross load basis;[11] it declines to revise its behind-the-meter generation, gross load, and Transmission Access Charge constructs, explaining that its volumetric methodology already allocates costs according to metered transmission use;[12] and it addresses transmission service flexibility through the new interconnection services described in Section D.[13]
PG&E supports CAISO’s proposal regarding cost allocation for co-located loads. First, with respect to the Transmission Access Charge, load served by behind-the-meter generation is not counted as Gross Load of a UDC for TAC purposes.[14] PG&E agrees that no change to this treatment is necessary because CAISO’s volumetric TAC methodology already allocates costs to each Large Load with behind-the-meter generation to the extent the Large Load uses the transmission system, as reflected by its metered load.[15] Second, PG&E supports the CAISO’s proposal that, consistent with FERC policy, co-located load should be counted on a gross load basis for purposes of procuring and allocating the costs of Black Start and Regulation services to UDCs.[16] PG&E agrees that, to implement this framework, it would be necessary for the PTOs to sub-meter each co-located Large Load independent of any onsite generation, and for Scheduling Coordinators for the LSEs serving those loads to report those meter values separately for the relevant charge codes.[17] PG&E recommends that CAISO clarify that sub-metering requirements apply to FERC-jurisdictional generation.
d. Please provide any other comments on this topic.
PG&E does not have additional comments at this time.
[1] CAISO Straw Proposal at 28–36; OSC at PP 88–102.
[2] CAISO Straw Proposal at 28; OSC at PP 88–89.
[3] CAISO Straw Proposal at 28.
[4] CAISO Straw Proposal at 28–31.
[5] CAISO Straw Proposal at 31–32.
[6] See CAISO Straw Proposal at 29 (Aug. 11, 2026).
[7] See id. at 30–31.
[8] See Cal. Pub. Util. Code § 218.
[9] See OSC at P 92.
[10] See CAISO Straw Proposal at 29–34.
[11] CAISO Straw Proposal at 33–34; OSC at PP 98–99.
[12] CAISO Straw Proposal at 34–36; OSC at P 102.
[13] CAISO Straw Proposal at 36.
[14] See id. at 34–35.
[15] See id. at 35–36.
[16] See id. at 33–34.
[17] See id. at 34.
4.
Please provide your organization’s comments on section D. New transmission services for flexible large loads.
a. Please provide comments on the Flexible Interim Load Interconnection (FILI) offering.
b. Please provide comments on the Flexible Load Interconnection – Permanent (FLIP) offering.
c. Please provide any other comments on this topic.
In Section D, the CAISO proposes to extend new transmission services to Eligible Customers taking service on behalf of flexible Large Loads. Rather than create new classes of transmission service, the CAISO proposes two new flexible interconnection service offerings that allow Large Loads to limit their energy withdrawals and interconnect more quickly and affordably.[1] The CAISO invites stakeholders to comment on which offerings it should prioritize.[2] PG&E addresses these proposals in turn, below.
a. Please provide comments on the Flexible Interim Load Interconnection (FILI) offering.
The CAISO proposes the Flexible Interim Load Interconnection (FILI) offering, an interim transmission interconnection service that would allow a Large Load to interconnect flexibly and receive service up to a level based on grid conditions until the network upgrades required for firm service are complete, at which point the load would transition to firm service.[3] The CAISO anticipates tailoring FILI to each Large Load’s point of interconnection and constraints and declines to propose any temporal or capacity cap on the offering.[4]
Please see response to 4.b, below.
b. Please provide comments on the Flexible Load Interconnection – Permanent (FLIP) offering.
The CAISO proposes the Flexible Load Interconnection–Permanent (FLIP) offering, a permanent transmission interconnection service that would allow a Large Load to interconnect while avoiding the need to fund or await network upgrades by accepting the terms of flexible interconnection service in perpetuity, customizable among the PTO, the CAISO, and the developer.[5] The CAISO asks stakeholders whether FLIP is worth pursuing at this time.[6]
PG&E supports the CAISO’s proposal to work toward offering two flexible interconnection products in the CAISO balancing area: Flexible Interim Load Interconnection (FILI) and Flexible Load Interconnection-Permanent (FLIP). Consistent with the CAISO Straw Proposal, FILI would enable Large Loads to interconnect flexibly and receive service up to a certain level based on grid conditions and constraints until network upgrades are complete, at which time the Large Load would transition to firm service. FLIP would enable Large Loads to interconnect and avoid the need to fund or wait for completion of network upgrades that would be required for firm load service by accepting conditional terms in perpetuity. PG&E emphasizes that the need for flexible service that accommodates innovative approaches is urgent. PG&E recommends that the CAISO initially focus on developing the interim flexible transmission interconnection service to gain experience with studying and operating these types of services before committing to offering a permanent flexible product like FLIP. This initial offering would provide Large Loads with the ability to interconnect more quickly than they otherwise would and would apply only until the network upgrades needed for firm service are complete.
PG&E recommends that FILI be renamed “Flexible Interim Large Load Interconnection” (FILLI) to more specifically indicate that the service will be limited to Large Loads, as defined in the Tariff, that are interconnecting to the transmission system and therefore are directly affecting the CAISO grid.
PG&E views the FILLI offering as consistent with FERC’s recent approval of similar interim, curtailment-based transmission services in other regions. In particular, SPP’s Conditional High Impact Large Load Service (CHILLS) provides a useful model.[7] Like FILLI, CHILLS provides an expedited path to service while permanent infrastructure is developed, includes curtailment provisions subject to tariff-defined scheduling priorities, and has a maximum term (seven years for CHILLS) to incentivize timely completion of permanent solutions.[8] The CAISO’s proposed FILI offering shares these core design features, and PG&E is confident that a similarly structured FILLI offering will satisfy FERC’s expectations for interim flexible transmission services as articulated in the Order to Show Cause.
As part of this stakeholder process, the CAISO and PTOs that will offer a FILLI service should determine what data, information, and operational control, if any, the CAISO should receive or exercise to facilitate the CAISO’s role in ensuring transmission system reliability. PG&E notes that it will be the PTO-LSEs who offer the service and expects that they will play an active role in coordinating with the CAISO and ensure consistent implementation details across the TO Tariffs.
PG&E recommends that the CAISO and the PTOs commit to making another filing by no later than a specified date to further consider the more permanent flexible transmission interconnection service that could avoid the need for Network Upgrades. This subsequent filing will benefit from the lessons learned working to implement and operationalize the interim flexible service and will further consider whether any rate adjustments are appropriate for a Large Load customer’s acceptance of conditional interconnection service on a permanent basis. As the CAISO notes, it will also be important to determine whether Large Load developers desire a permanent conditional interconnection service.
PG&E agrees that no new form of transmission service is necessary to implement the services described above, particularly as the TAC is cost-allocated on a kWh, not kW, basis—unlike any other RTO/ISO.
PG&E understands the PTOs would need to develop many aspects of the flexible interconnection services, including: (a) an overall framework in the PTO’s and CAISO’s respective tariffs, as appropriate, that identifies the roles and responsibilities for all impacted parties; (b) a pro forma Flexible Interconnection Service Addendum to the pro forma Large Load Interconnection Agreement (or, alternatively, a standalone pro forma Flexible Interconnection Agreement) that identifies the roles and responsibilities for impacted parties that will identify customer- and site-specific equipment and systems necessary to operationalize FILLI service; (c) study methodologies that recognize the unique operational characteristics of flexible Large Loads; (d) operational requirements, including curtailment implementation mechanisms and data reporting; (e) cost responsibility provisions, including any financial security during the conditional service period; (f) transition-to-firm provisions for FILLI that specify the automatic conversion to firm service upon network upgrade completion; and (g) coordination mechanisms between flexible interconnection service and the PTO study process.
Specifically with respect to the operational requirements, PG&E expects that fully enabling flexible connections (whether time-limited or permanent) may require customers to have capabilities to manage longer-duration curtailments. This capability could be achieved through traditional onsite generation or innovative approaches like virtual power plants. PG&E believes that the CAISO and the PTOs should ensure that pathways are available for these and other innovative approaches as flexible service is developed.
[1] CAISO Straw Proposal at 36–38; OSC at PP 101–104.
[2] CAISO Straw Proposal at 39.
[3] CAISO Straw Proposal at 38.
[4] CAISO Straw Proposal at 38.
[5] CAISO Straw Proposal at 38–39.
[6] CAISO Straw Proposal at 39.
[7] Sw. Power Pool, Inc., 195 FERC ¶ 61,196, at P 7 (2026) (“SPP CHILLS Order”).
[8] See OSC at PP 17-18 (citing SPP CHILLS Order).
5.
Please provide your organization’s comments on section E. Serving electrically proximate large loads.
In Section E, the CAISO addresses interconnection customers that serve electrically proximate Large Loads and co-located loads. While the CAISO proposes to allow co-located Large Loads and generation to be studied together regardless of their configuration, it declines to create provisions permitting interconnection customers to serve electrically proximate Large Loads, explaining that California developers have expressed no interest in the option and that the construct is designed to satisfy bring-your-own-generation requirements that California does not impose.[1]
PG&E supports the CAISO’s decision not to create new provisions specifically designed to serve electrically proximate loads.
[1] CAISO Straw Proposal at 39–40; OSC at PP 112–113.
6.
Please provide your organization’s comments on the Operational Forecasting Requirements.
The CAISO proposes ongoing forecasting and data-submission requirements so that it has sufficient visibility into Large Load behavior for planning and reliable operations, to be provided through the Large Load’s LSE’s Scheduling Coordinator.[1] Specifically, the CAISO proposes that the Scheduling Coordinator must provide:
- hourly load forecasts for the Operating Day and a rolling seven-day forecast horizon;
- day-ahead forecasts submitted by 0700 Prevailing Pacific Time, prior to the close of the day-ahead market;
- real-time forecast updates upon any material deviation from day-ahead submitted forecasts;
- telemetry data showing actual load consumption in real time; and
- expected outage information, including planned maintenance schedules and notice of forced outages.
PG&E agrees with the CAISO and the Commission that additional operational forecasting data will support continued reliability. PG&E proposes a separate working group to address what it views as significant logistics that would need to be addressed to enable this additional data exchange. PG&E notes that some of the necessary changes, particularly to software, may not be ready for implementation by 2027.
[1] CAISO Straw Proposal at 21–23.
7.
Please provide your organization’s comments on the proposed Technical Requirements.
The CAISO states that it agrees that the technical requirements the Commission identifies are necessary and proposes to adopt requirements developed through the Large Load Technical Requirements Working Group and its June 15, 2026 Technical Requirements Straw Proposal—including frequency and voltage ride-through, ramp-rate limitations, monitoring and telemetry, post-fault active power recovery, modeling data, and commissioning—supplemented by four requirements that close gaps the Order identifies.[1]
PG&E supports the CAISO’s efforts to develop additional technical requirements and remains committed to participation in the CAISO stakeholder processes, including through continuing to lead in the development of effective technical requirements.
[1] CAISO Straw Proposal at 18–21; OSC at P 63.
8.
Please provide your organization’s comments on the Technical Requirements under development.
The CAISO notes that the Large Load Technical Requirements Working Group continues to develop additional technical requirements that the Order does not address, to be refined based on stakeholder feedback, system studies, operating experience, and evolving NERC Reliability Standards for computational loads.[1] These emerging requirements include low- and high-frequency cycling, constant power operation, power quality, dynamic reactive power support, phase-angle jump ride-through, and protection requirements.[2]
PG&E supports the CAISO’s efforts to develop additional technical requirements and remains committed to participation in the CAISO stakeholder processes, including leading the development of effective technical requirements.
[1] CAISO Straw Proposal at 19.
[2] CAISO Straw Proposal at 19.
9.
Please provide any additional comments on the straw proposal or Aug 19 meeting discussion.
The CAISO raises several cross-cutting and procedural matters on which it invites stakeholder comment, including the expedited initiative timeline—with a draft final proposal in September 2026 and Board of Governors approval targeted for October 28, 2026—and the decisional classification of the proposed tariff changes, which the CAISO proposes would go to the Board of Governors only, with no role for the Western Energy Markets Governing Body.[1]
PG&E appreciates the opportunity to provide additional comments on the straw proposal and the August 19 stakeholder meeting discussion. Below, PG&E provides additional comments for consideration related to implementation of the flexible interconnection service offerings.
Overall, PG&E encourages the CAISO to continue developing the details of the proposed flexible interconnection service offerings, in particular with regard to how they will interact with the CAISO market operations. PG&E expects that flexible service offerings will require ongoing refinement even after they become available to customers, including with respect to market integration.
More specifically, PG&E notes that the Straw Proposal proposes that Large Load demand would be scheduled by the LSE’s Scheduling Coordinator similar to non-Large-Load demand,[2] but does not fully address how flexible load would be represented in market timeframes. PG&E offers the following questions for further consideration by the CAISO:
- What load would get bid into the day-ahead and real-time markets for Large Loads taking FILI or FLIP service?
- How will the flexibility associated with FILI and FLIP be represented in day-ahead scheduling and real-time dispatch?
- How will flexible Large Load be incorporated into the CAISO’s demand forecast and Residual Unit Commitment (RUC) process?
- At what volume of flexible Large Load will it become necessary to consider interaction with the Extended Day-Ahead Market (EDAM) and Day-Ahead Market Enhancements (DAME)?
- How will FILI and FLIP interact with existing demand response programs, given that flexible Large Loads may be functionally similar to demand response resources? Considering the CAISO’s responsibility to curtail schedules based on tariff-defined scheduling priorities if available transmission capacity is insufficient, how does the CAISO envision market changes to account for FILI and FLIP?
PG&E recommends that the CAISO convene a working group to address these market integration issues and develop protocols for how Scheduling Coordinators will represent flexible Large Loads in market submissions.
[1] CAISO Straw Proposal at 40–41.
[2] CAISO Straw Proposal at 21.
San Diego Gas & Electric
Submitted 09/02/2026, 05:53 pm
1.
Please provide your organization’s comments on section A. Transmission Service to eligible customers.
a. Please provide comments on the definition of large loads.
b. Please provide comments on the large load application process and interconnection study procedures.
c. Please provide comments on the large load operational requirements.
d. Please provide any other comments on this topic
SDG&E Response:
- The CAISO’s proposed definition of Large Loads[1] is similar to, but not the same as, the definition proposed in FERC’s Show Cause Order (SCO). FERC’s SCO states that the definition “…should be based on the characteristics of CAISO’s transmission system” and suggests that a reasonable definition for a Large Load would be a load that is “a new commercial or industrial customer, located at a single site behind one or more points of interconnection, and that has a peak load of 50 MW or greater, interconnects to the transmission system at a voltage level of greater than 69 kV, and is not part of a co-location arrangement.”[2]
The definition provided by the CAISO in its Straw Proposal does not include FERC’s suggestion that the definition be limited to “new” customers that are “commercial or industrial”. Furthermore, CAISO definition does not specify that the Large Load “interconnects to the transmission system at a voltage level of greater than 69 kV” and does not exclude loads that are “part of a co-location arrangement.” [3] The definition proposed by the CAISO should be revised to incorporate FERC’s suggestion that the Large Load must be from a “new commercial or industrial” customer. This change would recognize that existing customers connected their loads to the transmission system under rules that did not include the conditions proposed in the FERC SCO.
SDG&E notes that the FERC SCO’s reference to “a voltage level greater than 69 kV” is unlikely to have any practical effect since transmission networks operated below 100 kV are not designed to accommodate 50 MW load additions. Finally, given the characteristics of the CAISO’s transmission system, SDG&E agrees with the Straw Proposal’s recommendation that Large Loads be defined in terms of load that is connected to the CAISO Controlled Grid, because, by itself, the voltage threshold suggested by FERC is problematic. Some Large Loads could have a point of interconnection with sub-transmission facilities that are not under CAISO operational control. These sub-transmission facilities are subject to the jurisdiction of Local Regulatory Authorities (LRAs) rather than the FERC.
The co-location of Behind-The-Meter (BTM) generation with load, should not automatically result in End-Use load having peak Demand greater than 50 MW not meeting the Large Load definition. BTM generation may not always be available. Also, absent protective advance funding requirements, transmission ratepayers will be at risk for the costs of Network Upgrades that are built for load that does not materialize. These risks are not eliminated because generation is co-located with the load.
SDG&E agrees with the CAISO that consideration can be given to changing the definition to maintain consistency with the definition used by NERC to develop applicable reliability standards.
- Eligible Customers (as defined by the existing definition of Eligible Customers in SDG&E’s existing Transmission Owner (TO) Tariff) requesting service on behalf of a Large Load will submit an application (as provided for in SDG&E’s existing TO tariff) to SDG&E for service via SDG&E-owned transmission facilities at a point of interconnection to the CAISO Controlled Grid. Applications will be processed by SDG&E pursuant to SDG&E’s TO Tariff, as amended in response to FERC’s SCO.
Any Network Upgrades that SDG&E determines are needed to accommodate the amount of power requested in the customer’s application, will be reviewed with the CAISO. CAISO concurrence with the identified Network Upgrades is required in order for SDG&E to move forward with the upgrades. CAISO involvement in this step is necessary for cohesive transmission planning (i.e., all transmission facilities planned in the same process, as opposed to piecemeal planning).
- SDG&E supports including in its amended TO Tariff, some of the operational requirements listed in the CAISO straw proposal. However, SDG&E does not agree that the CAISO should have the physical ability to disconnect Large Loads. The retail service provider has the customer relationship and should have sole ability to disconnect the Large Load should such disconnection become necessary. SDG&E notes that CAISO already has arrangements in place with PTOs by which the CAISO requests, and the PTOs implement, emergency load reduction in order to avoid cascading outages. These arrangements are routinely reviewed and modified to remain effective and to minimize the burden on the most vulnerable end-use customers. The utilities are best positioned to identify the loads that can and/or should be disconnected in response to a CAISO request.
The FERC SCO permits the CAISO to explain how its existing processes provide the grid reliability that FERC is concerned with[4] respect to physical load disconnection by the CAISO, the CAISO should avail itself this invitation and explain in its response to the FERC SCO that the CAISO’s existing procedures provide grid reliability in the event involuntary load reduction is necessary; the CAISO does not need to have physical load disconnection capability.
- The CAISO’s Straw Proposal indicates the CAISO’s intent is to propose “a number of data requirements for the large load interconnection study procedures, described in Section A.4, to ensure the CAISO has the necessary information to account for [load] flexibility.”[5] The requirements would require Scheduling Coordinators to provide the CAISO, among other things, the following information:
“Real-time forecast updates: Updated forecasts whenever expected consumption of the large load materially deviates from previously submitted day-ahead forecasts, including:
o Expected energization activities
o Material changes in operations
o Curtailments
o Facility outages
o Co-located generation impacts on the load forecast
o Other known events affecting expected consumption”[6]
While Scheduling Coordinators might have near real-time information on a Large Load’s expected grid withdrawal quantities, Scheduling Coordinators are unlikely to have access to the specific real-time information listed above. Obtaining such real-time information on an ongoing basis will be very challenging because it depends on the Large Load’s ability and willingness to continually share its internal business processes with third parties. The CAISO should not require Scheduling Coordinators to provide this real-time information.SDG&E notes that the FERC SCO’s discussion of flexible Large Loads does not suggest that collection and provision of the above-listed real-time information is necessary to accommodate load flexibility in a reliable manner.
[1] “An End User located at a single site interconnecting to the CAISO Controlled Grid, and that has a peak load of 50 MW or greater.” CAISO Straw Proposal, p. 9.
[2] FERC SCO, paragraph 57.
[3] FERC SCO, paragraph 57.
[4] “CAISO and/or the Participating Transmission Owners should explain whether the tariffs remain just and reasonable without these or other ongoing operational requirements as part of the rates, terms, and conditions of transmission service or propose tariff revisions establishing necessary ongoing operational requirements.” FERC SCO, paragraph 63.
[5] CAISO Straw Proposal, p. 12.
[6] CAISO Straw Proposal, p. 23.
2.
Please provide your organization’s comments on section B. Framework to prevent cost-shifting.
a. Please provide comments on roles and responsibilities to prevent cost shifting.
b. Please provide comments on data transparency.
c. Please provide any other comments on this topic.
SDG&E Response:
- FERC’s SCO expresses concern regarding the transparency of Network Upgrade cost “assignment.” FERC SCO also expresses concern with the CAISO’s lack of a “pro forma cost recovery agreement between CAISO, the relevant transmission owner, and the Eligible Customer taking transmission service on behalf of large loads that help ensure that Eligible Customers bear the risk and are ultimately responsible for costs incurred to provide transmission service, including the cost of network upgrades.”[1]
The CAISO tariff’s low and high voltage Transmission Access Charge (TAC) mechanisms provide clear cost assignment for Network Upgrades. These cost assignments reflect FERC’s long-standing policy determinations that networked transmission provides benefits to all customers and that it is very difficult to determine which specific customers benefit by what amount from any particular network facility. Accordingly, socialization of Network Upgrade costs as provided in the existing CAISO tariff is appropriate. SDG&E suggests that in the CAISO’s response to the FERC SCO, the CAISO reference FERC’s previous findings on cost assignment for Network Upgrades within the CAISO Balancing Authority Area. These findings are as applicable today as they were when the FERC approved the rates framework reflected in the CAISO’s tariff.
The FERC SCO indicates concern with the possibility of “speculative requests” to connect Large Loads, the network upgrades that could be built in response to such requests, and the potential adverse downstream cost impact on transmission ratepayers. FERC preliminarily finds that “in order to prevent unjust and unreasonable cost shifting among transmission customers, it appears necessary for CAISO, the relevant transmission owner, and the Eligible Customer taking transmission service on behalf of a large load to enter into a cost recovery agreement that requires the Eligible Customer to make a minimum contribution toward the transmission owner’s transmission revenue requirement if the Eligible Customer ultimately takes less transmission service than anticipated because the large load does not materialize as planned or is not developed at all.”[2] If the Large Load does not materialize at the levels studied by the PTO, then the Large Load’s payments to the utility for transmission service are lower than anticipated when the need for the Network Upgrades was originally studied and identified. This effectively shifts the costs of any Network Upgrades built as a result of the Large Load energization request to all other CAISO transmission ratepayers.
Requiring the Eligible Customer requesting service on behalf of the Large Load to provide advance funding of necessary Network Upgrades will help to mitigate this cost shifting risk. The TO tariffs, and accompanying Large Load interconnection agreement, will set forth these advance funding requirements as well as subsequent reimbursement contingent on the studied load actually materializing. SDG&E has preliminarily concluded that the CAISO needs to be a party to this agreement. As a signatory, the CAISO is affirming that the advance funding adequately mitigates the cost shift risk across all TAC-paying LSEs. The CAISO’s participation will ensure that any differences among the CAISO PTOs’ interconnection agreements for advance funding and subsequent reimbursement will not result in an unjust or unreasonable TAC. The CAISO’s participation will also provide the CAISO’s concurrence that the identified Network Upgrades are necessary for grid reliability and consistent with the CAISO’s Transmission Planning Process (TPP) outcomes.
The CAISO’s response to FERC’s SCO should indicate that the CAISO will be a party to the interconnection agreement between the PTO and the Eligible Customer taking transmission service on behalf of Large Loads. The CAISO’s response should also explain that an advance funding requirement will satisfy FERC’s requirement that the Eligible Customer is “ultimately responsible” for Network Upgrade costs; specifically, that to the extent the Large Load does not materialize as planned, there is no reimbursement of advanced funds and the Large Load bears the full proportion of those Network Upgrade costs.
Finally, the CAISO’s response to the FERC SCO should point out that an advance funding requirement has the added advantage that it creates an incentive for Large Loads to interconnect at transmission locations that do not require costly Network Upgrades. Such locations will help to minimize the Large Load’s carrying costs associated with advance funding.
[1] FERC SCO, paragraph 65.
[2] FERC SCO, paragraph 80.
3.
Please provide your organization’s comments on section C. Requirements for co-located arrangements.
a. Please provide comments on terminology.
b. Please provide comments on serving co-located loads.
c. Please provide comments on cost allocation for co-located loads.
d. Please provide any other comments on this topic.
SDG&E Response:
- It would be helpful in the CAISO’s response to the FERC SCO (including possibly in its own tariff filing), for the CAISO to provide a more complete description of the various co-location arrangements that are possible, and not possible, under the CAISO tariff and the CAISO’s role in processing the associated interconnection requests. For example, it is possible that a Large Load may request to interconnect behind the meter of an existing Participating Generator meter. Or a generator may request to interconnect behind the meter of an existing Large Load. It is also possible that a developer could request interconnection of a new Large Load combined with new on-site generation. It may be that existing CAISO and PTO interconnection processes are sufficient for handling the various co-location possibilities, but further explanation would be beneficial for stakeholders and the FERC.
- See SDG&E’s response to question 3.a.
- The interconnection agreement that allows a Large Load to be energized will set forth the requirements for the advance funding of required Network Upgrades, and subsequent reimbursement contingent on the studied load actually materializing.
- Co-location of load and generation creates distinctly different study possibilities. These include cases where (i) the Large Load is off-line at the same time the generation is on-line, and (ii) the Large Load is on-line at the same time that the generation is off-line. Interconnection studies will need to account for these possibilities.
4.
Please provide your organization’s comments on section D. New transmission services for flexible large loads.
a. Please provide comments on the Flexible Interim Load Interconnection (FILI) offering.
b. Please provide comments on the Flexible Load Interconnection – Permanent (FLIP) offering.
c. Please provide any other comments on this topic.
SDG&E Response:
The CAISO’s Straw Proposal states that “the CAISO and PTOs propose to create two new flexible load interconnection services that will enable faster and more affordable interconnections.”[1] On this issue, however, the FERC SCO is only directed at the CAISO. FERC in the SCO preliminarily finds that the “CAISO’s Tariff appears to be unjust and unreasonable because it does not include transmission services that reflect Eligible Customers taking transmission service on behalf of flexible large loads that are willing and able to limit their use of the transmission system under certain conditions.”[2] FERC explains that it is directing this finding “only to CAISO because, unlike in other sections of this order, it appears that only CAISO’s Tariff is implicated because CAISO is the transmission provider.”[3]
Since the FERC SCO does not identify deficiencies in PTO tariffs, the CAISO’s response to the FERC SCO should not indicate that the “PTOs” will necessarily create new flexible load interconnection services. Also, the flexible load interconnection services described in the CAISO’s response should align with the scope of concerns identified by FERC in the SCO. Specifically, FERC’s SCO does not require the CAISO to provide flexible load interconnection services to Large Loads that are “co-located with generation.”[4] This means that the CAISO’s flexible load interconnection services only need to be available to Large Loads that are willing and able to either (i) partially energize the loads requested in their interconnection applications, or (ii) limit their grid withdrawals through direct load control technologies (e.g., thermal storage that would reduce electric air conditioning loads during certain conditions).
The CAISO Straw Proposal indicates that the CAISO intends to respond to FERC’s SCO by proposing a Flexible Interim Load Interconnection (FILI) service and a Flexible Load Interconnection - Permanent (FLIP) service. SDG&E will work with CAISO and other stakeholders to determine if the CAISO’s FILI and FLIP proposals align with FERC’s expectation.
SDG&E agrees with both CAISO and FERC that interim interconnection solutions can facilitate timely customer energization while Network Upgrades are being developed. SDG&E can already offer transmission-level interim load interconnection service arrangements through its existing customer consultation and study process when system conditions permit. Instead of committing to FILI and FLIP offerings, the CAISO’s response to FERC’s SCO could avail itself of FERC’s offer that “In the alternative, CAISO may explain whether, given that CAISO does not offer the transmission services required by Order No. 888, CAISO’s existing transmission service framework addresses the concerns described herein.”[5]
- As discussed above, the FERC SCO identifies issues regarding flexible transmission service in the CAISO’s tariff, not in the PTOs’ tariffs and the CAISO should not therefore submit a response to the FERC’s SCO that indicates that the “PTOs” will necessarily offer a FILI service. Also as discussed above, SDG&E will work with CAISO and other stakeholders to determine if the current CAISO’s FILI proposal aligns with FERC’s expectation.
Nevertheless, the PTO’s TO tariffs could include an offering in response to FERC’s SCO. If not already allowed under the PTO’s existing tariff, this offering would allow Large Loads to energize a portion of their load pending completion of necessary Network Upgrades.
- It is premature for the CAISO to indicate to the FERC that the PTOs’ TO tariffs will provide a FLIP offering. A FLIP offering is problematic in that it presumes a Large Load will be willing to indefinitely limit its electric consumption below its commercially-desired level. Unless the Large Load were somehow compensated for this inconvenience, it is doubtful that Large Loads will be interested in a FLIP offering. It seems more likely that the PTO and Eligible Customer serving the Large Load will reach an up-front understanding of the amount of interconnection service that can be offered without incurring a large up-front Network Upgrade cost responsibility. In this event, the FLIP will not be of interest to the Large Load.
If the Large Load does express interest in a FLIP, the Large Load will likely request some form of compensation in exchange for limiting its grid withdrawals and the commercial activity that such withdrawals would otherwise enable. Compensation raises numerous issues, not the least of which is the incentive it creates for a Large Load to overstate the amount of load it intends to add. Determining the appropriate amount of compensation will also be challenging since any particular Large Load’s agreement to permanently limit its grid withdrawals may only defer, not avoid, Network Upgrades. Other load growth may create the need for the Network Upgrade so the Large Customer’s agreement to limit its own consumption may not translate into permanent benefits for transmission ratepayers. Finally, as the CAISO notes in its straw proposal, “developers consistently express that they are only interested in acquiring firm service and would only agree to be flexible temporarily to interconnect before completion of long-lead network upgrades.” There is no immediate need to develop a FLIP.
For the above reasons, SDG&E recommends that the CAISO’s response to the FERC SCO indicate that efforts to develop a FLIP can be deferred until Large Load developers express an interest in such an offering. Deferring development of a FLIP until there is interest from Large Load developers is consistent with just and reasonable rates.
- Depending on how a FILI and FLIP offerings are structured and implemented there could be significant real-time operational challenges. For example, a single annual import limit established in the interconnection agreement is relatively straight-forward since it is comparatively easy for the Large Load to adhere to a single limit and since the limit is determined through planning studies and is not dependent on real-time inputs. Conversely, if the limits are set close to, or in, real-time, it will be far more challenging for the Large Load to adjust its business activities since grid conditions are very dynamic. The CAISO’s involvement in setting limits close to or in real-time is critical given the CAISO’s greater visibility into anticipated real-time system conditions.[6]
[1] CAISO Straw Proposal, p. 38.
[2] FERC SCO, paragraph 104 (emphasis added).
[3] FERC SCO, footnote 222.
[4] “For purposes of this order, ‘flexible’ large loads are a subset of large loads, as used in this order, that are not co-located with generation, but are willing and able to limit their energy withdrawals from the transmission system under certain conditions.” FERC SCO, footnote 218.
[5] FERC SCO, paragraph 105.
[6] Any limits on the amount of power a customer can withdraw from the grid require enforcement mechanisms. FERC recognizes this requirement: “an Eligible Customer must have necessary control technologies and/or protection systems, which may include a special protection scheme, to limit its energy withdrawals to its approved level.” FERC SCO, paragraph 105.
5.
Please provide your organization’s comments on section E. Serving electrically proximate large loads.
SDG&E Response:
SDG&E agrees with the CAISO’s proposed treatment of electrically proximate large loads.
6.
Please provide your organization’s comments on the Operational Forecasting Requirements.
SDG&E Response:
See SDG&E’s response to question 1.d.
7.
Please provide your organization’s comments on the proposed Technical Requirements.
SDG&E Response:
SDG&E supports the technical requirements referenced in the CAISO straw proposal. It would be helpful in the CAISO’s response to the FERC SCO to indicate which of the referenced technical requirements will be codified in the CAISO tariff and which will be incorporated by reference to NERC and/or the WECC.
8.
Please provide your organization’s comments on the Technical Requirements under development.
SDG&E Response:
With the exception of the CAISO’s ability to physically disconnect Large Loads (see SDG&E’s response to question 1.c), SDG&E agrees that the CAISO should continue developing the operational requirements identified in FERC’s SCO that have not been fully addressed by the Large Loads Technical Requirements Straw Proposal.[1]
[1] CAISO Straw Proposal, p. 20.
9.
Please provide any additional comments on the straw proposal or Aug 19 meeting discussion.
SDG&E Response:
Firm versus Non-Firm Service
The CAISO straw proposal uses the terms “firm” and “non-firm” at various points. In the CAISO’s response to the FERC SCO, it is important that the CAISO explain that all uses of the CAISO transmission grid are “firm” in the sense that transmission service is guaranteed when market clearing prices exceed seller’s offer prices and are below buyer’s bid prices.[1] FERC has previously determined that price/quantity bids and offers via the CAISO’s market mechanisms provide transmission service consistent with FERC Order 888’s open access principle.[2] Interconnection service, on the other hand, may be considered “non-firm” to the extent a Large Load agrees to limit its grid withdrawals in order to partially energize its requested load pending completion of required Network Upgrades (the CAISO’s proposed FILI offering).
Large Load Queue Spreadsheets
The CAISO’s straw proposal “encourages the PTOs to memorialize tariff requirements to adopt large load queue spreadsheets…”[3] There is no requirement in FERC’s SCO for PTOs to maintain spreadsheets that list the Large Loads that have submitted an interconnection application. Further SDG&E does not currently, nor plan to, “queue” load interconnection applications in the sense that outside of the timing of when applications are submitted, some customers requesting load energization get priority ahead of other customers requesting load energization. The CAISO’s response to the FERC SCO should not suggest that SDG&E develops and maintains “large load queue spreadsheets.”
Recovery of Costs Incurred to Provide Ancillary Services
In connection with Large Loads’ cost responsibility for the CAISO’s regulation and black start services, the CAISO Straw Proposal states that the CAISO will require the PTOs to “sub-meter each co-located large load independent of any onsite generation” and “report those meter values separately” to the CAISO for purposes of billing each Large Load with co-located generation.[4] The CAISO Straw Proposal also states that the CAISO is not proposing to “revise its current constructs for behind-the-meter generation, gross load, and the transmission access charges.”[5] These two statements appear to be at odds with one another since separate billing of Large Loads by the CAISO appears to be a revision of the current construct for recovering the costs the CAISO incurs to provide regulation and black start services. Under the current construct, the CAISO bills LSEs, not individual end-use customers, for the costs the CAISO incurs to provide regulation and black start services. It is also odd that the FERC SCO singles out regulation and black start services, and not all of the other ancillary services that the CAISO acquires through its market.
The CAISO should clarify the apparently conflicting statements in its straw proposal. More significantly, the CAISO’s response to FERC’s SCO should explain whether the CAISO’s current construct for recovering the costs the CAISO incurs to provide all ancillary services becomes unjust or unreasonable upon the introduction of Large Loads. As presented in the CAISO Straw Proposal, it is not evident that the current cost recovery construct is flawed.
Allocation of Costs to Large Loads
The CAISO Straw Proposal states that the “CAISO would allocate costs to each large load with behind-the meter generation to the extent the large load used the transmission system, as reflected by its metered load.” The CAISO allocates costs to LSEs, not to individual customers including Large Loads. The CAISO should clarify this statement.
Unnecessary Network Upgrades
According to the Straw Proposal, “enabling flexibility will offer cost savings by avoiding unnecessary network upgrades.”[6] “Unnecessary network upgrades” is misleading language since the CAISO and the PTOs only identify network upgrades that they determine are necessary. To do otherwise would be imprudent.
Customer Confidentiality
As CAISO implements provisions of FERC’s Show Cause Order regarding publicly posting information regarding network upgrades triggered by large loads, it is important to maintain confidentiality as required by law and prudent business practice. SDG&E suggests that in its response to the FERC SCO, the CAISO explain how it intends to protect confidential information while at the same time providing the transparency that the FERC SCO requires. The SCO acknowledges the importance of confidentiality: “To the extent there are concerns about data confidentiality, CAISO and the Participating Transmission Owners should consider whether there are ways to mitigate those concerns while still providing the necessary transparency.”.[7]
[1] Emergency conditions can require the CAISO to undertake out-of-market actions in order to maintain overall grid reliability.
[2] See Pacific Gas & Electric Co., et al., 81 FERC ¶ 61,122 (Oct. 30, 1997)
[3] CAISO Straw Proposal, p. 27.
[4] CAISO Straw Proposal, p. 33.
[5] CAISO Straw Proposal, p. 35.
[6] CAISO Straw Proposal, p. 36.
[7] FERC SCO, paragraph 75.
Valley Electric Association, Inc.
Submitted 09/02/2026, 10:34 am
Submitted on behalf of
Valley Electric Association, Inc.
1.
Please provide your organization’s comments on section A. Transmission Service to eligible customers.
a. Please provide comments on the definition of large loads.
b. Please provide comments on the large load application process and interconnection study procedures.
c. Please provide comments on the large load operational requirements.
d. Please provide any other comments on this topic
Valley Electric Association, Inc. (“VEA”) submits these comments on the CAISO’s Large Loads Straw Proposal, posted August 12, 2026. VEA appreciates the opportunity to provide feedback on the Straw Proposal and supports the Straw Proposal’s central idea, preserving Participating Transmission Owners’ (“PTO”) lead role over load interconnection, while layering CAISO data-exchange, transparency, and operational requirements on top. That framework is workable for VEA, but it does not represent VEA’s specific circumstances.
VEA is a small, member-owned, nonprofit cooperative serving a territory almost entirely in Nevada, and it is also the load-serving entity and scheduling coordinator for its members. VEA also owns and operates its own 138 kV transmission system. For most large loads, however, VEA will likely not be the interconnecting PTO. The higher-voltage facilities a large load at or above the 50 MW threshold would need are owned by GridLiance West, LLC, a separate PTO operating within VEA’s service area. The realistic sequence of events is that the load applies for service, GridLiance studies and processes the request under its own TO tariff in consultation with VEA, and VEA requests that service on the customer’s behalf and schedules the resulting load. The Straw Proposal assumes a single PTO holds every role in its territory. That assumption holds for most investor-owned utilities in CAISO’s footprint, but it does not hold for VEA. The CAISO’s Straw Proposal should account for a small PTO that is more likely to request interconnection service as a load serving entity (“LSE”) for a large load, rather than provide interconnection service to a large load.
VEA provides four recommendations for consideration:
1. Where a large load’s service will run over the facilities of a PTO other than the LSE, CAISO should confirm that PTO leads the interconnection study, large load application process, and PTO-alignment work, in consultation and coordination with the LSE. The LSE should have a defined opportunity to review and provide input on decisions that materially affect its ability to serve the load.
2. Any obligations that attach to VEA should be proportionate to VEA’s geographic footprint, size, and staffing, not to the scale of an investor-owned utility. In addition, the process requirements should account for the fact that VEA is unlikely to receive significant, if any, demand by large loads for interconnection to its 138 kV transmission system, especially since most of the data center opportunities in VEA’s service area are located in Nye County, Nevada, which recently adopted a ban on data center construction.
3. CAISO should allow flexibility for other power marketing entities to schedule the large load’s demand, subject to the LSE’s consent.
4. Every PTO’s tariff should carry minimum developer cost allocation principles, because VEA’s members generally pay the same regional Transmission Access Charge for its load as everyone else, regardless of where large-load upgrades occur.
Three features of VEA’s situation should inform every recommendation. First, VEA is the only LSE in the CAISO footprint outside California, so the California-specific rules and regulations the Straw Proposal refers to do not necessarily govern VEA or its Nevada local regulatory authority. VEA, as a member-owned cooperative organized under Nevada law, is also not subject to the state commission regulation and oversight that govern investor-owned utilities elsewhere in the CAISO footprint. Second, VEA’s historical system peak is on the order of 140 MWs, so a single 50 MW campus can equal a third of VEA’s entire load, and campuses being marketed in the Pahrump-Amargosa corridor routinely exceed that. Lastly, while VEA will keep the direct retail and billing relationship with the customer, it will not necessarily be the sole entity that studies the interconnection or owns the facilities the customer connects to.
CAISO should not assume that whichever entity holds the “PTO” or “LSE” label can absorb the Straw Proposal’s full range of obligations. It should designate the PTO that owns the interconnecting facilities as the lead study and application entity, require that PTO to consult with the load-serving entity on matters affecting the local distribution and retail obligations, and keep the load-serving entity’s own obligations proportionate. This will ensure flexibility for VEA.
a. Definition of Large Load
No comment.
b. Large Load Application Process and Interconnection Study Procedures
VEA supports keeping interconnection studies with the PTOs under their own tariffs. CAISO should clarify that where service runs over a PTO other than the customer’s LSE, that PTO leads the study. For projects in VEA’s service territory that require the interconnecting PTO’s system, that PTO should run the study in consultation with VEA, which holds the retail relationship and local operational knowledge a transmission-only study can miss. CAISO’s expectation that PTOs “align study processes” should be qualified by system size and request volume, whichever PTO is aligning. CAISO should also establish minimum process requirements for non-load-serving PTOs interconnecting large loads, including a standardized application process, study timelines comparable to those of load-serving PTOs, and minimum study methodologies consistent with CAISO’s planning assumptions, together with defined coordination procedures with the load-serving entity, so that VEA and the interconnecting PTO operate under the same expectations.
On CAISO’s ability to reject study results for “high operational risk or uncertainty,” VEA asks for objective published criteria, a cure opportunity, deference to the interconnecting PTO’s study on local matters, and defined concurrence timelines. On speculative requests, CAISO’s proposal relies on the CEC’s IEPR forecast. Deterrence of speculative or duplicative loads should fall to VEA’s and the PTO’s own tariffs and rules (deposits, readiness milestones, site-control showings), and CAISO’s planning inputs may misstate VEA-area load growth to the extent they depend on CEC data never designed to reach outside California.
The proportionality point above also applies to CAISO’s expectation that PTOs “align application processes.” The Straw Proposal envisions each PTO adopting a consistent process covering the application itself, application fees and readiness requirements, and information and data requirements, and as drafted the Straw Proposal expects that alignment to extend across every LSE in its footprint regardless of size. Where a PTO other than VEA is the interconnecting PTO, that alignment expectation should run to that PTO’s process for the relevant project, conducted in consultation and collaboration with VEA, not create a parallel obligation on VEA to build and maintain application infrastructure of its own that it would use only occasionally, for a narrow set of projects. VEA does not have the staff, application-tracking systems, or engineering team that an IOU-scale application process presumes, and requiring VEA to replicate that process rather than participate in it would be a wasted expenditure that produces no additional benefit for CAISO, the interconnecting PTO, or the large-load customer. Any required changes to VEA’s TO Tariff should reflect these limitations.
Consultation and collaboration should be a substantial part of the process. VEA should have a defined opportunity to review and comment on the application terms that touch its own retail relationship with the customer, including readiness milestones, deposit and security requirements, and the information the PTO collects that VEA will later need to schedule and bill the resulting load. VEA should also have standing to flag any local distribution-interface conditions or retail service considerations that a transmission-focused application process might not otherwise provide for. That collaborative role lets the PTO retain a single, consistent application process across its system while still accounting for the operational and commercial realities specific to VEA.
c. Please provide comments on the large load operational requirements
No comment.
d. Other Comments – Large Load Service Agreements
No comment.
2.
Please provide your organization’s comments on section B. Framework to prevent cost-shifting.
a. Please provide comments on roles and responsibilities to prevent cost shifting.
b. Please provide comments on data transparency.
c. Please provide any other comments on this topic.
a. Roles and Responsibilities to Prevent Cost-Shifting
CAISO declines to impose a top-down cost allocation rule, leaves cost allocation and the pro forma cost recovery agreement to PTO tariffs, and concludes that no change to the regional Transmission Access Charge is needed because construction contributions offset rate base and existing adjustment mechanisms suffice.
High-voltage network upgrades driven by large loads anywhere in the CAISO footprint flow into the single regional TAC that VEA’s members pay. CAISO’s no-TAC-change conclusion rests entirely on an assumption that every PTO’s tariff will actually require developers to fund the upgrades their own loads cause. Nothing in the Straw Proposal requires this. Each PTO negotiates its own cost allocation tariff in its own stakeholder process, where VEA has no input, and a PTO competing for a large-load customer may have an incentive to under-collect from that customer and let the shortfall be socialized through rate base rather than lose the project to a PTO with more favorable cost allocation terms. Those costs do not stay contained within the PTO that made the choice. Because most PTOs’ transmission revenue requirements feed the same regional TAC, a customer-favored cost allocation tariff anywhere in the system becomes a cost VEA’s members help pay, with none of the economic development benefit that accrued to the PTO that brought in the load. VEA therefore requests minimum cost-causation safeguards and transparency requirements rather than rely solely on PTO discretion. CAISO, as the entity responsible for regional transmission planning and reliability assessment, is well positioned to determine the extent to which network upgrades are driven by a specific large load interconnection rather than broader regional load growth, much as CAISO already allocates network upgrade costs among generator interconnection customers using metrics such as the generation distribution factor. CAISO should develop minimum cost allocation principles and a methodology reflecting that distinction, which PTOs would then implement through their respective tariffs. At minimum, PTO tariffs should include consistent principles designed to ensure that large-load customers bear the costs they cause and that transmission customers throughout the CAISO footprint are protected from stranded-investment and cost-shifting risks.
b. Data Transparency
VEA also requests annual monitoring and public reporting of large-load-driven additions to each PTO’s transmission revenue requirement, so that stakeholders can verify the assumption CAISO’s conclusion depends on.
c. Other Comments
The Straw Proposal contemplates that the pro forma interconnection agreement will run between the interconnecting PTO and the large load customer. For projects located in VEA’s service territory, where a PTO other than VEA holds the interconnecting facilities, that means the agreement will run between that PTO and the customer, not VEA. VEA needs a defined role in that agreement that reflects its separate function as the LSE. CAISO should adopt a pro forma framework that makes the load-serving entity a party to, or at minimum a required signatory or reviewing party on, the large load interconnection service agreement, rather than a purely bilateral agreement between the interconnecting PTO and the customer.
VEA’s own system will likely require network upgrades to deliver the resulting load, at the interface between the interconnecting PTO’s transmission facilities and VEA’s distribution and sub-transmission system, and potentially further into VEA’s own system depending on where the load sits. A two-party agreement between the interconnecting PTO and the customer would not completely capture the scope, cost responsibility, or construction timeline for those VEA upgrades. The pro forma framework CAISO adopts should make clear that VEA’s own network upgrade costs and construction obligations are addressed in the pro forma interconnection agreement. VEA should therefore participate directly in the drafting of these pro forma agreements to protect its network-upgrade interests and to preserve cooperative-specific terms, including membership requirements, board policies, and credit and security provisions scaled to VEA’s requirements.
3.
Please provide your organization’s comments on section C. Requirements for co-located arrangements.
a. Please provide comments on terminology.
b. Please provide comments on serving co-located loads.
c. Please provide comments on cost allocation for co-located loads.
d. Please provide any other comments on this topic.
No comment.
4.
Please provide your organization’s comments on section D. New transmission services for flexible large loads.
a. Please provide comments on the Flexible Interim Load Interconnection (FILI) offering.
b. Please provide comments on the Flexible Load Interconnection – Permanent (FLIP) offering.
c. Please provide any other comments on this topic.
No comment.
5.
Please provide your organization’s comments on section E. Serving electrically proximate large loads.
No comment.
6.
Please provide your organization’s comments on the Operational Forecasting Requirements.
No comment.
7.
Please provide your organization’s comments on the proposed Technical Requirements.
No comment.
8.
Please provide your organization’s comments on the Technical Requirements under development.
VEA appreciates CAISO’s continued leadership on the Large Load Technical Requirements effort and looks forward to participating in the development of any requirements that may affect small, non-IOU load-serving entities like VEA.
9.
Please provide any additional comments on the straw proposal or Aug 19 meeting discussion.
No comment.
Viridon California
Submitted 08/28/2026, 02:56 pm
1.
Please provide your organization’s comments on section A. Transmission Service to eligible customers.
a. Please provide comments on the definition of large loads.
b. Please provide comments on the large load application process and interconnection study procedures.
c. Please provide comments on the large load operational requirements.
d. Please provide any other comments on this topic
Introductory Comments
Viridon California LLC (Viridon) appreciates the CAISO’s efforts to develop a framework to respond to the issues identified in the Federal Energy Regulatory Commission’s (FERC’s) June 18, 2026 order to show cause (Order) on large load interconnection issues. The CAISO’s Straw Proposal accurately identified the issues to be addressed in CAISO and participating transmission owner (PTO) responses to the Order. As a current PTO and independent transmission developer actively engaged in building, owning and operating CAISO-approved transmission, Viridon looks forward to coordinating to ensure that all issues raised in the Order are thoroughly and clearly addressed to provide large load customers timely and cost-effective access to the CAISO controlled grid.
Through its subsidiaries, Viridon is both a CAISO PTO and the approved project sponsor for new transmission facilities identified for construction in the CAISO’s Transmission Planning Process (TPP). The TPP-approved facilities Viridon is currently developing include approximately 500 miles of new 500 kV transmission lines and associated substation and other infrastructure in Northern and Central California. Viridon, like other independent transmission developers, owns and operates transmission infrastructure in the CAISO, but does not serve end-use load customers.
Non-load serving entity PTO (non-LSE PTO) facilities can and should be used to provide transmission access to large load customers, especially because they can provide cost-effective and expedited access to the larger transmission grid. To ensure non-LSE PTOs can provide transmission service, the combined CAISO and PTO tariffs must adequately describe and distinguish the planning, operations, ownership, and cost allocation/recovery mechanisms for the CAISO, PTOs, relevant utility distribution companies (UDCs), LSEs, and end-use customers. As with the current TPP and generator interconnection processes, the load interconnection process should ensure that non-LSE PTOs have the opportunity to study and identify upgrades to their facilities, as well as the right to construct, own, and operate those upgrades.
Viridon understands that the nature of the CAISO’s market and transmission service construct raises complicated questions regarding how to define each entity’s appropriate roles and responsibilities. Viridon looks forward to working with the CAISO, PTOs and stakeholders regarding how to resolve these issues in a way that optimizes use of the current and planned transmission system.
Part a – Large Load Definition
Viridon supports the CAISO’s proposed definition of Large Load, which does not include a voltage threshold but instead applies to interconnections to the CAISO Controlled Grid. Specifying interconnection to the CAISO Controlled Grid appropriately delineates between federal and state jurisdiction.
Part b – Large Load Application and Study Procedures
Viridon agrees with CAISO’s Straw Proposal regarding the need for enhanced coordination between the CAISO and PTOs on the load and resource interconnection processes. The Straw Proposal notes that the CAISO “expects the PTOs to align application processes in order to ensure the level of visibility necessary for the CAISO to plan for new large loads and maintain reliability once they are interconnected.” Viridon agrees that consistency and transparency are necessary to provide fair and non-discriminatory service to large load customers.
Viridon also agrees with the Straw Proposal’s intention to clarify its “concurrence process” to address potential local network needs associated with large load interconnections. As part of the CAISO concurrence process, Viridon suggests including an opportunity for potentially affected PTOs to identify downstream upgrades on their own systems.
The Straw Proposal also recognizes that non-LSE PTOs could be impacted by large load interconnection requests and encourages PTOs to work together to clarify complementary roles and responsibilities. Viridon agrees, and further suggests that the CAISO and PTO tariffs provide a consistent, transparent, and non-discriminatory application and study process that allows all relevant parties, including large load customers, to optimize transmission interconnection to the CAISO-controlled grid. Transparency and coordination are fundamental to ensure large load customers can evaluate interconnection options that provide the best value and “speed-to-power.”
The application and study process for new large load interconnections should enable PTOs, UDCs, LSE, and customers to identify and evaluate preferred points of interconnection on any CAISO PTO transmission facilities without intermediaries. Viridon understands that the current CAISO framework and the Order contemplate that “Eligible Customers,” i.e., utilities, will seek transmission service on behalf of large loads.[1] Under such a framework, it is particularly important that end-use customers have both (1) the necessary information to evaluate potential points of interconnection and (2) the ability to select a preferred point of interconnection independent from the UDC or LSE. A framework that relies on the UDC to select the end-use customer’s point of interconnection does not provide effective open access to the transmission system, especially if the end-use customer has no information to assess alternative interconnection options.
Viridon looks forward to exploring potential large load interconnection application and study processes that, similar to the generator interconnection process, ensure consistency between PTOs while also providing transparent data and non-discriminatory grid access to large load customers.
Part c – Large Load Operational Requirements
Viridon generally agrees with the operational requirements identified in the Order and the Straw Proposal. The CAISO and/or PTO tariffs should consistently identify which entities will provide the operational requirement data and which entities will receive such data.
Viridon provides specific comments regarding operational requirement data in the table below:
|
Operational Requirement Identified in FERC Order to Show Cause (P63)
|
Viridon Comments
|
|
Hourly forecasts
|
The CAISO Straw Proposal appropriately proposes that day-ahead and real-time information will come from the load-serving entity scheduling coordinator responsible for the large load’s demand. Information should also be provided to all applicable PTOs.
|
|
Telemetry data & Monitoring Equipment
|
Both the UDC/LSE and the PTO (where not the same entity) should be eligible to require, install, and charge the large load customer for monitoring and telemetry equipment. PTOs and UDC/LSEs need visibility into telemetry and planned/forced outage data for interconnecting large loads for maintenance and ratings purposes.
|
|
Remote disconnection
|
The CAISO Straw Proposal notes that it does not have direct control of switches, “so the PTOs would need to make sure they have control at the right level. In other words, these requirements would be implemented at the PTO rather than at the
CAISO level.”[2] Non-LSE PTOs execute ISO/reliability coordinator operating instructions like any other directive, with protection tripping as designed. However, non-LSE PTOs have no retail relationship with the end-use customer and should bear no responsibility for curtailment decisions made for commercial or service-level purposes.
The curtailment decision and customer relationship belong with the UDC/LSE under CAISO direction. To the extent flexible interconnection service is offered, there must be clear directives from the UDC/LSE and/or the CAISO to enable such action.
|
The CAISO Straw Proposal also contemplates CAISO tariff provisions enabling data exchanges with the PTOs and LSEs to ensure access to specific large load interconnection information. Viridon agrees that the CAISO tariff should implement an adequate information-sharing framework among the relevant parties.
Viridon generally agrees with the Straw Proposal’s suggestion that it will obtain large load data from the PTOs during the interconnection process and the load-serving entities representing the large load’s demand in market timeframes.[3]
[1] See Order at Paragraph 3.
[2] Straw Proposal at 21.
[3] Straw Proposal at 23.
2.
Please provide your organization’s comments on section B. Framework to prevent cost-shifting.
a. Please provide comments on roles and responsibilities to prevent cost shifting.
b. Please provide comments on data transparency.
c. Please provide any other comments on this topic.
Part a – Roles and Responsibilities to Prevent Cost Shifting
Viridon agrees with the need to implement a pro forma cost recovery agreement to avoid cost shifting and the Straw Proposal’s acknowledgement that PTOs that will construct and own network upgrades associated with large load interconnections.[1] To ensure terms are consistent, just, and reasonable, the pro forma cost recovery agreement should ensure there are clear financial arrangements between the PTO, the UDC/LSE and large load customer, as necessary. It is unclear whether a pro forma agreement limited to the PTO and the Eligible Customer could adequately prevent the cost shifting concerns FERC identified in the Order. Viridon suggests that LSEs and large load customers provide their perspectives regarding how to structure potential multi-party agreements to address FERC’s cost shifting concerns.
The CAISO’s preliminary proposal indicates that cost allocation principles should be set forth in PTO tariffs rather than the CAISO tariff, partially on the assumption that PTOs “have a direct relationship with their retail ratepayers and the regulators of those ultimate rates, including the CPUC.”[2] This assumption is not true for non-LSE PTOs that do not have direct relationships with retail ratepayers and are not rate regulated by the CPUC. Instead, any contributions in aid of construction (i.e., large load upfront funding) and reimbursement mechanisms associated with upgrades to non-LSE PTO facilities will be defined in FERC-regulated tariffs.[3]
For investor-owned utility PTOs (IOU-PTOs), the CPUC may directly provide rules for upfront funding mechanisms and large load customer reimbursement. Non-LSE PTOs are not subject to CPUC regulation and will have FERC-approved tariffs governing these issues. While these mechanisms will necessarily be implemented through different regulatory frameworks, they should apply consistent principles for protecting customers against the cost-shifting concerns identified in the FERC Order, without creating barriers to large load customers interconnecting with non-LSE PTO facilities.
Part b – Data Transparency
Viridon supports the Straw Proposal’s commitment to post aggregate large load additions, associated network upgrades, and cost estimates in a searchable format. Viridon requests two enhancements. First, large load interconnection requests of a size material to regional flows, including requests at extra-high voltage buses, should be visible in the TPP stakeholder process rather than solely through the CEC demand forecast, so that stakeholders can evaluate system impacts. Second, potentially affected PTOs should receive notice of large load interconnection requests that may impact their facilities so that downstream impacts can be identified during the study process.
[1] Straw Proposal at 25.
[2] Straw Proposal at 25.
[3] Though ultimate cost allocation is subject to CPUC jurisdiction.
3.
Please provide your organization’s comments on section C. Requirements for co-located arrangements.
a. Please provide comments on terminology.
b. Please provide comments on serving co-located loads.
c. Please provide comments on cost allocation for co-located loads.
d. Please provide any other comments on this topic.
4.
Please provide your organization’s comments on section D. New transmission services for flexible large loads.
a. Please provide comments on the Flexible Interim Load Interconnection (FILI) offering.
b. Please provide comments on the Flexible Load Interconnection – Permanent (FLIP) offering.
c. Please provide any other comments on this topic.
Parts a and b – FILI and FLIP Offerings
Viridon supports development of both the FILI and FLIP offerings. For either offering to function, curtailment obligations must be enforceable and the chain of authority must be clear: the CAISO directs, the UDC/LSE implements the curtailment with the end-use customer, and the interconnecting PTO acts only pursuant to CAISO or Reliability Coordinator operating instructions. Experience with existing reliability-based demand response arrangements suggests that voluntary curtailment commitments are difficult to enforce in practice. Flexible interconnection service agreements should therefore include clear performance obligations, verification through the telemetry and monitoring requirements described above, and meaningful consequences for non-performance, so that the flexibility credited in interconnection studies is realized in operations.
5.
Please provide your organization’s comments on section E. Serving electrically proximate large loads.
6.
Please provide your organization’s comments on the Operational Forecasting Requirements.
7.
Please provide your organization’s comments on the proposed Technical Requirements.
8.
Please provide your organization’s comments on the Technical Requirements under development.
9.
Please provide any additional comments on the straw proposal or Aug 19 meeting discussion.
