Comments on May 28 Storage Design and Modeling Meeting

1. Please provide a summary of your organization’s comments on the May 28, 2025 working group discussion.

The California Community Choice Association (CalCCA) appreciates the opportunity to submit comments on the May 28, 2025, working group meeting. In summary, the California Independent System Operator (CAISO) should:

• Revise its proposed path forward for representing nonlinearity to implement a Master File parameter expeditiously, and in the interim, direct storage resources to use the “Technical Limitations Not in the Market Model” outage card, for the reasons described in CalCCA’s May 22, 2025, comments;[1] and

Seek to clearly differentiate between other instances where storage bid cost recovery (BCR) is either “warranted” or “unwarranted” and begin tailoring solutions to those differences.

[1]            See CalCCA Comments on May 9 Working Group Meeting (May 22, 2025): https://stakeholdercenter.caiso.com/Comments/AllComments/a278055e-4347-4ae8-bfd5-abdc49e61dad.

2. Please provide your organization’s comments on the topics related to Outage Management, particularly on the different means to represent foldback in the near-term and their relationship to availability incentives.

CalCCA reiterates its previous position. That is, the CAISO should revise its proposed path forward for representing nonlinearity to implement a Master File parameter expeditiously, and in the interim, direct storage resources to use the “Technical Limitations Not in the Market Model” outage card, for the reasons described in CalCCA’s May 22, 2025, comments.[1]  As an interim measure, the CAISO and/or the Department of Market Monitoring should review and validate the use of the “Technical Limitations Not in the Market Model” outage card to ensure that its use depicts actual physical constraints as intended by this stakeholder initiative and that it is not being misused. The CAISO should seek to finalize the near-term solution and communicate it to stakeholders as soon as possible so that scheduling coordinators have clarity on how to represent nonlinearity.

[1]            Ibid.

3. Please provide your organization’s comments on Uplift & DEB: Insights into Charging Bid Mitigation.

CalCCA appreciates the CAISO’s analysis on charging bid mitigation and how it impacts storage bids and states of charge. The Storage Bid Cost Recovery [BCR] and Default Energy Bids Enhancements stakeholder initiative revealed that it will be important to consider instances of mitigation when determining how to apply BCR to storage resources. As a next step, the CAISO and stakeholders should clearly differentiate between other instances where BCR is either “warranted” or “unwarranted” and begin tailoring solutions to those differences.

4. Please provide your organization’s comments on the PG&E’s presentation.

CalCCA has no comments on Pacific Gas and Electric Company’s presentation at this time.

5. Please provide any additional comments.

CalCCA has no additional comments at this time.

1. Please provide a summary of your organization’s comments on the May 28, 2025 working group discussion.

Comments on Storage Design and Modeling

May 28, 2025 Presentation

Department of Market Monitoring

June 11, 2025

Summary

The Department of Market Monitoring (DMM) appreciates the opportunity to comment on the Storage Design and Modeling May 28, 2025 working group presentation.[1] These comments reiterate DMM’s position on storage bid cost recovery (BCR) issues, mitigation and default energy bids of storage resources, and the proposal to extend usage of dynamic limits to storage resources.

DMM continues to encourage the ISO to address the storage BCR issues as a top priority. Specifically, DMM recommends the ISO address the real-time bidding incentives created by the current BCR design for batteries.

DMM appreciates the ISO’s analysis on the mitigation of charging bids for storage resources. DMM continues to recommend the ISO develop a dynamic default energy bid (DEB) for storage resources that can vary by hour. A storage DEB that reflects intraday opportunity costs that vary across the day would support efficient mitigation.

As noted in DMM’s last round of comments, DMM conditionally supports extending the use of dynamic limits to storage resources.[2] However, this support is conditional on sufficient ability for DMM and the ISO to monitor and enforce appropriate usage of this functionality, and rules that storage resources would be ineligible for BCR when dynamic limits impact dispatch.

Comments

Storage BCR

DMM continues to encourage the ISO to address storage BCR design as the top priority of this initiative. The current BCR rules remove the exposure to real-time prices for storage resources, which incentivize batteries to submit real-time bids that are inconsistent with their real-time opportunity costs. This creates efficiency, gaming, and reliability concerns. While the ISO developed a tariff amendment to mitigate some gaming concerns, the underlying incentive issues will continue to result in inefficient dispatch of storage resources in the real-time market.[3]  

The BCR framework was designed for traditional resources and does not consider attributes of batteries, such as state-of-charge. Therefore, the same situations in which traditional resources should receive BCR will not translate directly to situations where storage resources should receive BCR. DMM recommends redesigning BCR rules to assume no BCR eligibility for batteries and add eligibility only under specific situations where this is deemed appropriate.  

DMM does not argue that there are no circumstances in which storage resources should receive BCR. However, these circumstances should be specifically carved out to avoid over-extending BCR to storage resources and distorting their bidding incentives. DMM continues to recommend that the ISO and stakeholders work together to determine situations where BCR is appropriate for storage resources.  

DMM reiterates that it is not just gaming concerns that result from the current BCR design, but a lack of incentive for storage resources to bid in such a way that reflects expected real-time intraday opportunity costs and system conditions. When resources are properly incentivized to reflect these costs (including the potential need to buy-back day-ahead schedules at very high prices in the peak net load hours), real-time dispatch instructions should align much more closely with day-ahead schedules and support storage resources being available when most needed in real-time.  

DMM continues to recommend the ISO clearly identify where storage BCR is warranted and remove BCR payments for storage in any other scenarios, to ensure that storage resources are properly incentivized to submit bids that accurately reflect actual real-time costs so that the market optimization achieves efficient market outcomes.[4]

Mitigation and the storage DEB

DMM appreciates the ISO’s analysis on historical mitigation of charging bids. The ISO’s analysis indicates that incremental dispatch (or foregone charging) due to mitigation of charging bids appears minimal across most of the storage resources.[5] These results are similar to the ISO’s conclusion during the August 19, 2024 working group that incremental dispatch caused by mitigation on the discharging side was low.[6] DMM also provided analysis supporting this same conclusion as part of this stakeholder process in 2024.[7]

DMM agrees that mitigation does not appear to have historically had a large impact on the dispatch of most storage resources. However, to further understand whether mitigation of charging or discharging bids is causing storage resources to be unavailable in peak hours, DMM recommends the ISO provide more detailed analysis of certain resources on certain days, particularly the units that were frequently mitigated and the days where conditions were tight in the peak hours.

DMM continues to recommend establishing dynamic DEBs that can vary by hour, to reduce the risk of mitigation to values that do not reflect varying real-time intraday opportunity costs. As previously discussed, because the current opportunity cost component of the real-time storage DEB is calculated from day-ahead prices, the real-time DEB only reflects the opportunity cost of a binding financial agreement from the day-ahead, rather than the opportunity cost in the real-time.[8] To dispatch batteries efficiently, bids should reflect the potential opportunity costs of charging or discharging batteries in the real-time market. These costs can change throughout the day, based on the state of the battery and remaining charge and discharge opportunities in future intervals. Therefore, DEBs for batteries used when bid mitigation is triggered need to vary across the day to reflect these dynamic intraday opportunity costs.[9]

DMM continues to recommend the ISO work with stakeholders to develop a method to calculate a real-time intraday opportunity cost for storage that could be incorporated into the storage DEB. Such an approach could result in DEBs that are higher in some hours, but lower in others, and would support more efficient mitigation that aligns with real-time intraday opportunity costs that vary across the day.[10]

Changing BCR rules should not be delayed until changes to DEBs are developed

While DMM continues to recommend that the storage DEB should be enhanced to reflect intraday opportunity costs, the changes to BCR rules recommended by DMM should not be deferred or delayed until such enhancements to DEBs are made. In 2024, DMM provided analysis examining whether the efficiency gains of properly incentivizing batteries to submit higher bids in the hours prior to the peak net load hours by removing BCR for battery buy-backs would be undermined by mitigation. The analysis showed that with the current storage DEB, even if batteries bid very high (e.g., $1,000/MWh), mitigation would likely have had minimal impact on dispatch prior to the peak net load hours on critical days.[11] 

Extension of dynamic limit functionality to storage resources

DMM continues to support the development of market model improvements that incorporate nonlinearities in storage resource charging and discharging capabilities (i.e., foldback).[12] As previously stated, DMM believes a more appropriate solution would be to include foldback into resource characteristics through Master File, and allow scheduling coordinators to bid based on their state-of-charge (SOC).[13] The ISO indicated these enhancements are not feasible in the short-term and proposed extending the hybrid resource dynamic limit functionality to storage resources as an interim solution.

In the last set of comments, DMM detailed conditional support for this interim solution.[14] To reiterate, DMM would support allowing storage resources to utilize dynamic limits in the short-term if: (1) the ISO tariff clearly specifies acceptable use of dynamic limits for storage resources, (2) the ISO requires new Master File data sufficient for monitoring usage of dynamic limits, and (3) resources would be ineligible for real-time bid cost recovery during hours when dynamic limits impact the resource’s dispatch. However, in the long-term, DMM continues to recommend the ISO sunset this feature and develop market functionality to manage operational nonlinearities.

[1] Working Group on Outage Management, Uplift & DEB, and SOC Management presentation, California ISO, May 28, 2025: https://stakeholdercenter.caiso.com/InitiativeDocuments/Presentation-StoradeDesignandModeling-May28-2025.pdf

[2] Comments on Storage Design and Modeling Issue Paper and Straw Proposal on Outage Management, Nonlinearity, and SOC Clarification, Department of Market Monitoring, May 23, 2025: https://www.caiso.com/documents/dmm-comments-on-storage-design-and-modeling-issue-paper-and-straw-proposal-on-outage-management-nonlinearity-and-soc-clarification-may-23-2025.pdf

[3] Tariff Amendment to Prevent Unwarranted Bid Cost Recovery Payments to Storage Resources, and Request for Effective Date on Shortened Notice, California ISO, November 26, 2024: https://www.caiso.com/documents/nov-26-2024-tariff-amendment-bid-cost-recovery-to-storage-resources-er25-576.pdf

[4] Comments on Storage Design and Modeling Working Group Session 1, Department of Market Monitoring, January 8, 2025: https://www.caiso.com/documents/dmm-comments-on-storage-design-and-modeling-working-group-session-dec-11-2024-jan-8-2025.pdf

[5] Working Group on Outage Management, Uplift & DEB, and SOC Management presentation, California ISO, May 28, 2025, p 21: https://stakeholdercenter.caiso.com/InitiativeDocuments/Presentation-StoradeDesignandModeling-May28-2025.pdf

[6] Storage Bid Cost Recovery and Default Energy Bid Enhancements Stakeholder Meeting, California ISO, August 19, 2024, pp 29-30: https://stakeholdercenter.caiso.com/InitiativeDocuments/Presentation-Storage-Bid-Cost-Recovery-and-Default-Energy-Bids-Enhancements-Aug-19-2024.pdf

[7]  Comments on Storage Bid Cost Recovery and Default Energy Bid Enhancements Revised Straw Proposal, Department of Market Monitoring, September 23, 2024: https://www.caiso.com/documents/dmm-comments-on-storage-bid-cost-recovery-and-default-energy-bid-enhancements-revised-straw-proposal-sep-23-2024.pdf

[8] Comments on Storage Design and Modeling Working Group Session 2 and 3, Department of Market Monitoring, March 7, 2025: https://www.caiso.com/documents/dmm-comments-on-storage-design-and-modeling-working-group-sessions-2-and-3-mar-07-2025.pdf

[9] Comments on Storage Bid Cost Recovery and Default Energy Bid Enhancements August 19, 2024 Stakeholder Meeting, Department of Market Monitoring, August 26, 2024: https://www.caiso.com/documents/comments-on-storage-bid-cost-recovery-and-default-energy-bid-enhancements-august-19-2024-stakeholder-meeting-aug-26-2024.pdf

[10] Comments on Storage Design and Modeling Working Group Session 2 and 3, Department of Market Monitoring, March 7, 2025: https://www.caiso.com/documents/dmm-comments-on-storage-design-and-modeling-working-group-sessions-2-and-3-mar-07-2025.pdf

[11] Storage Bid Cost Recovery and Default Energy Bid Enhancements Stakeholder Meeting, California ISO, August 19, 2024, pp 29-30: https://stakeholdercenter.caiso.com/InitiativeDocuments/Presentation-Storage-Bid-Cost-Recovery-and-Default-Energy-Bids-Enhancements-Aug-19-2024.pdf

[12] Comments on Storage Design and Modeling Issue Paper and Straw Proposal on Outage Management, Nonlinearity, and SOC Clarification, Department of Market Monitoring, May 23, 2025: https://www.caiso.com/documents/dmm-comments-on-storage-design-and-modeling-issue-paper-and-straw-proposal-on-outage-management-nonlinearity-and-soc-clarification-may-23-2025.pdf

[13] Comments on Storage Design and Modeling Working Group Session 2 and 3, Department of Market Monitoring, March 7, 2025: https://www.caiso.com/documents/dmm-comments-on-storage-design-and-modeling-working-group-sessions-2-and-3-mar-07-2025.pdf

[14] Comments on Storage Design and Modeling Issue Paper and Straw Proposal on Outage Management, Nonlinearity, and SOC Clarification, Department of Market Monitoring, May 23, 2025: https://www.caiso.com/documents/dmm-comments-on-storage-design-and-modeling-issue-paper-and-straw-proposal-on-outage-management-nonlinearity-and-soc-clarification-may-23-2025.pdf

2. Please provide your organization’s comments on the topics related to Outage Management, particularly on the different means to represent foldback in the near-term and their relationship to availability incentives.

Please see the PDF attached below the final question for DMM's fully formatted complete set of comments. For the reader's convenience, the complete text of the comments is pasted in response to #1, but there may be some formatting errors.

3. Please provide your organization’s comments on Uplift & DEB: Insights into Charging Bid Mitigation.

Please see the PDF attached below the final question for DMM's fully formatted complete set of comments. For the reader's convenience, the complete text of the comments is pasted in response to #1, but there may be some formatting errors.

4. Please provide your organization’s comments on the PG&E’s presentation.

Please see the PDF attached below the final question for DMM's fully formatted complete set of comments. For the reader's convenience, the complete text of the comments is pasted in response to #1, but there may be some formatting errors.

5. Please provide any additional comments.

Please see the PDF attached below the final question for DMM's fully formatted complete set of comments. For the reader's convenience, the complete text of the comments is pasted in response to #1, but there may be some formatting errors.

1. Please provide a summary of your organization’s comments on the May 28, 2025 working group discussion.

The Public Advocates Office at the California Public Utilities Commission (Cal Advocates) appreciates the opportunity to comment on the California Independent System Operator Corporation’s (CAISO) May 28, 2025 meeting on CAISO’s Storage Design and Modeling initiative.[1]

Cal Advocates provides the following recommendations:

• CAISO should maintain the Resource Adequacy Incentive Mechanism (RAAIM) during conditions of storage foldback to properly incentivize storage to make its full Resource Adequacy (RA) capacity available to the market.
• CAISO should not prioritize modifications to Local Market Power Mitigation (LMPM) for storage charging bids in this initiative because CAISO has shown the impact of LMPM is minimal.  Instead, CAISO can use warranted Bid Cost Recovery (BCR) payments to mitigate any financial impacts to storage due to LMPM.
• CAISO should eliminate storage BCR eligibility except under the limited circumstances of exceptional dispatch, LMPM, and multi-interval optimization.

[1] CAISO, Storage Design and Modeling initiative, started November 25, 2024.  Initiative information available at: https://stakeholdercenter.caiso.com/StakeholderInitiatives/Storage-design-modeling.

2. Please provide your organization’s comments on the topics related to Outage Management, particularly on the different means to represent foldback in the near-term and their relationship to availability incentives.

CAISO provided a summary of stakeholder comments on near-term foldback representation, indicating that some stakeholders support the exemption of storage foldback from RAAIM.[1]  CAISO also summarized other stakeholders’ support for the continued application of RAAIM incentives to help ensure that energy storage’s full contracted RA capacity is offered to the market.[2]  Ratepayers bear a resource’s RA cost whether or not its full capacity is actually available to the market.  RAAIM is needed to provide incentives to ensure that the contracted RA capacity is delivered.

Cal Advocates agrees with the CAISO’s Department of Market Monitoring (DMM) and Southern California Edison Company (SCE) that storage foldback should not be exempt from RAAIM in the near-term.[3]  RAAIM is CAISO’s primary tool to enforce RA must offer obligations, and exemptions from RAAIM would undermine incentives for storage to bid its full capacity under stressed grid conditions when the capacity is most needed.

Some stakeholders argue that foldback is comparable to ramp dispatch limits for thermal resources that are exempt from RAAIM and that declining to exempt storage foldback from RAAIM would be discriminatory.[4]  However, similar discriminatory treatment in favor of storage already exists.  Namely, if resource owners wish to avoid RAAIM penalties due to predictable unavailability, they may reduce their Net Qualifying Capacities (NQC) to account for the unavailability.  This often occurs today when thermal generation voluntarily reduces NQCs to account for ambient derates.[5]  Another example is the CPUC accreditation option for hydro resources which decreases the resource’s NQC to account for drought-conditions and provides an exemption from RAAIM penalties.[6]  Exempting foldback from RAAIM penalties, rather than use of a voluntary NQC decrease or adjustments to accreditation, would subject other resources to discriminatory treatment.

[1] The RAAIM applies financial penalties to unavailable RA resource capacity during certain hours of the day.  CAISO, Resource Adequacy Issue Paper, November 7, 2024 at 52-53.  Available at: https://stakeholdercenter.caiso.com/InitiativeDocuments/Issue-Paper-Resource-Adequacy-Modeling-and-Program-Design-Nov-07-2024.pdf.

[2] CAISO, Storage Design and Modeling, Working Group on Outage Management, Uplift & DEB, and SOC Management, May 28, 2025 (CAISO Presentation) at 12.  Available at: https://stakeholdercenter.caiso.com/InitiativeDocuments/Presentation-StoradeDesignandModeling-May28-2025.pdf.

[3] DMM comments on the May 9 working group meeting, May 23, 2025 at Section 1; and SCE comments on the May 9 working group meeting, May 27, 2025 at Section 3.  Available at: https://stakeholdercenter.caiso.com/Comments/AllComments/a278055e-4347-4ae8-bfd5-abdc49e61dad.

[4] CAISO Presentation at 12.  See also California Energy Storage Alliance comments on the May 9 working group meeting, May 23, 2025 at Section 3.  Available at: https://stakeholdercenter.caiso.com/Comments/AllComments/a278055e-4347-4ae8-bfd5-abdc49e61dad.

[5] Scheduling Coordinators may propose to use a qualifying capacity value that accounts for ambient derates, though CAISO recognizes that not all resources use the option nor use a consistent approach to account for ambient derate impacts.  CAISO, Resource Adequacy Issue Paper, November 7, 2024 at 33.  Available at: https://stakeholdercenter.caiso.com/InitiativeDocuments/Issue-Paper-Resource-Adequacy-Modeling-and-Program-Design-Nov-07-2024.pdf.  See also California Public Utilities Commission (CPUC), 2020 Qualifying Capacity Methodology Manual, November 2020 (CPUC QC Manual) at 12.  Available at: https://www.cpuc.ca.gov/-/media/cpuc-website/files/legacyfiles/q/6442466773-qc-manual-2020.pdf.

[6] This voluntary accreditation for hydro resources is available to dispatchable hydro resources accredited by the CPUC’s Qualifying Capacity methodology.  CPUC QC Manual at 18. 

3. Please provide your organization’s comments on Uplift & DEB: Insights into Charging Bid Mitigation.

Stakeholders have expressed concern that CAISO’s Local Market Power Mitigation (LMPM) process results in the downward mitigation of storage charging bids.[1]  A decrease of a storage resource’s charge bid could result in a reduction in storage charging relative to the unmitigated bid if the mitigated bid is lower than the competitive Locational Marginal Price (LMP).  If the LMPM process is triggered and a mitigated charging bid is lower than the LMP, the storage resource will not charge and may not have sufficient state-of-charge (SOC) to meet energy or ancillary service awards in later periods.  CAISO did not propose a solution to this issue in the May 28, 2025 meeting, and it is not clear whether a viable solution exists due to the technical requirements of CAISO’s market optimization.

However, CAISO’s analysis of historical LMPM bid mitigation indicates that the impact of charging bid mitigation is minimal.  CAISO indicates that the frequency of charging side mitigation is less than 1% for most resources, although there are infrequent but higher outliers.[2]  Given the minimal impact of LMPM on charging bids, and the technical challenges under CAISO’s existing market optimization and the storage market model, there is no urgency to address charging bid mitigation in this initiative.

A more viable approach, and one that aligns with the objectives of the current initiative, is to instead address any potential financial impacts of LMPM through BCR.  CAISO’s Market Surveillance Committee (MSC) indicates that BCR due to LMPM is one of the limited circumstances in which storage BCR may be warranted.[3]  The MSC proposes that CAISO could implement BCR in this limited situation in a similar manner as the BCR methodology for exceptional dispatch.[4]

In comments on the Storage Bid Cost Recovery and Default Energy Bids Enhancements initiative, Cal Advocates supported DMM’s recommendation to eliminate most BCR for storage resources except under specific circumstances, including LMPM.[5]  Cal Advocates agrees with DMM that CAISO should start with the presumption that storage is ineligible for BCR and add eligibility for specific cases potentially related to exceptional dispatch, mitigation, and muti-interval optimization.[6]

[1] CAISO Presentation at 16.  CAISO’s market optimization requires storage resources to submit a non-decreasing bid curve over the range of the resource’s capacity, from Pmin (negative Pmax) to Pmax.  Non-decreasing (or monotonic) bid curves are necessary to ensure that CAISO's market optimization formulation is tractable.  If the LMPM is triggered, any segment along the bid curve that is above the Default Energy Bid (DEB) and the Locational Marginal Price (LMP) on both the charge bid segments and discharge bid segments will be adjusted to preserve the monotonicity of the bid curve.

[2] CAISO Presentation at 18 and 24.

[3] CAISO Market Surveillance Committee, Opinion on Storage Bid Cost Recovery, November 1, 2024 (MSC Opinion) at 17.  Available at: https://www.caiso.com/documents/market-surveillance-committee-final-opinion-storage-bid-cost-recovery-nov-01-2024.pdf

[4] MSC Opinion at 18.

[5] Cal Advocates comments on the Revised Straw Proposal, Storage Bid Cost Recovery and Default Energy Bids Enhancements initiative, September 23, 2024 at Section 2.  Available at: https://stakeholdercenter.caiso.com/Comments/AllComments/04a134b1-3874-498a-ab08-e075048095e5#org-9e00b1ef-dcf2-42dd-be2e-588c91080e62.

[6] DMM comments on the December 11, 2024 working group meeting at Section 1.  Available at: https://stakeholdercenter.caiso.com/Comments/AllComments/2b83f24a-ad3a-4c29-aae1-b3997d81b383#org-cd0cba90-b130-4bc7-ac97-f4358b8cd1e2.

4. Please provide your organization’s comments on the PG&E’s presentation.

Pacific Gas and Electric Company (PG&E) offered a thoughtful perspective on the interrelationship among SOC, flexible ramping, BCR, RA, and foldback.  PG&E described conceptual approaches to modify the existing non-generating resource (NGR) market model or develop a new storage market model to incorporate SOC-based bids.[1]  These modified market models have the potential to address the many gaps in the existing storage model identified by CAISO and stakeholders.  However, PG&E recognizes that its conceptual ideas are longer-term solutions that require substantial stakeholder review, and that CAISO may not be able to implement these solutions until 2028.[2]

Cal Advocates appreciates PG&E’s balanced presentation on BCR reform,[3] a central topic of the Storage Design and Modeling initiative that has not been addressed in the stakeholder workshops to date.  PG&E suggests that a parallel effort to identify and modify CAISO’s storage market model to mitigate out-of-market CAISO dispatch decisions that drive BCR could offer a robust solution for eliminating unwarranted storage BCR.[4]  Moreover, PG&E offered an “unofficial” viewpoint that DMM’s position that storage should not receive BCR at all, or under limited conditions, may be reasonable if storage has greater control of its real-time SOC.[5]  Cal Advocates agrees that there are a number of longer-term market reform solutions that could address unwarranted BCR.

Until CAISO can implement longer-term market model improvements, Cal Advocates recommends that CAISO eliminate storage BCR eligibility except under the limited circumstances identified by DMM and MSC.

[1] PG&E presentation at the May 28, 2025 working group meeting (PG&E Presentation) at 8-9.   Available at: https://stakeholdercenter.caiso.com/InitiativeDocuments/Presentation-StoradeDesignandModeling-May28-2025.pdf.

[2] PG&E Presentation at 10.

[3] PG&E Presentation at 7.

[4] PG&E Presentation, May 28, 2025.  Recording available at: https://www.youtube.com/watch?v=z84z63TXxpQ at 2:12:18.

[5] PG&E Presentation, May 28, 2025.  Recording available at: https://www.youtube.com/watch?v=z84z63TXxpQ at 2:13:00.

5. Please provide any additional comments.

In comments on the initial January 2025 meeting of the Storage Design and Modeling initiative, Cal Advocates urged CAISO to prioritize comprehensive BCR reform and highlighted similar recommendations from DMM and MSC.[1]  The Final Proposal in the Storage BCR and DEB Enhancement initiative, approved by CAISO’s Board of Governors and the Western Energy Imbalance Market (WEIM} Governing Body on November 7, 2024, preserved unreasonable ratepayer-borne BCR payments that result from storage’s inability to meet day ahead (DA) dispatch awards due to operator-driven insufficient SOC.[2]  The MSC Opinion on the Draft Proposal identified numerous shortcomings in CAISO’s partial BCR reform.[3]  The MSC indicated that while the partial BCR reform may eliminate extreme inflated cases of unwarranted BCR, on the whole the partial BCR reform would likely be ineffective in eliminating most unwarranted BCR.[4]  The MSC also pointed to CAISO’s lack of empirical data that makes it “impossible” to assess whether CAISO’s partial BCR reform fixes the problem of unwarranted BCR.  

CAISO should provide a comparison at the June 30 stakeholder meeting on BCR[5] of BCR payments since the implementation of the partial BCR reform to the counterfactual without the partial BCR reform over the same period.  CAISO should also provide overall historical trends in storage BCR payments.  CAISO must ensure that any proposed BCR reform addresses the shortcomings identified by the MSC and DMM.  At a minimum, CAISO should disallow most storage BCR except under specific circumstances that warrant BCR or demonstrate with empirical historical data that any alternative reform has an equivalent outcome.

[1] Cal Advocates comments on working group session 1, January 8, 2025 at Section 1.  Available at: https://stakeholdercenter.caiso.com/Comments/AllComments/2b83f24a-ad3a-4c29-aae1-b3997d81b383#org-e242b7ec-a271-4164-9b4d-2ddce44bd10d.

[2] CAISO, Storage Bid Cost Recovery and Default Energy Bid Enhancements, Final Proposal for Track 1, October 31, 2024 at 14.  Available at: https://stakeholdercenter.caiso.com/InitiativeDocuments/Final-Proposal-Storage-Bid-Cost-Recovery-and-Default-Energy-Bids-Enhancements-Oct-31-2024.pdf.

[3] MSC Opinion at 28-30.

[4] MSC Opinion at 28.

[5] CAISO Presentation at 7.

1. Please provide a summary of your organization’s comments on the May 28, 2025 working group discussion.

The California Energy Storage Alliance (CESA) appreciates the opportunity to comment on the May 28, 2025 working group.  CESA believes that sufficient discussion among stakeholders has occurred for CAISO to publish a Draft Final Proposal (DFP) on outage reporting, nonlinearity, and SOC definition & calculation. 

With regards to outage management enhancements, CAISO should include the following OMS enhancements in the DFP to be implemented in the soonest possible market release:   

• Overlapping outage cards that can adjust Availability, Load Max, Max Energy and Min Energy values on one card
• Allowing non-NULL values in addition to NULL for other cards (as related to ancillary services [AS])
• Creating a single Out-of-Service checkbox for Non-Generator Resources (NGRs)
• Allowing for Load Max (Pmin) rerates on Test Energy cards during New Resource Implementation 
• Allowing automatic acceptance of updates to forced outage cards

In addition, the CAISO should include any clarifying language it proposes to include in the Outage Management BPM in the DFP.  This will allow stakeholder review prior to publication of the PRR to kick off the BPM change process.

The use of Technical Limitations Not in Market Model nature of work (NOW) is an appropriate near-term solution for storage operators to reflect nonlinearity and should be included in the DFP.  As discussed below, a broad coalition of stakeholders have clearly justified that outages to reflect nonlinearity should not be subject to RAAIM penalties.  The use of dynamic limits, including “current rates” as resource specific values in the MasterFile, and evaluating a new biddable SOC storage model should be discussed as part of the SOC Management Topics of this initiative.

With regards to SOC definition and calculation, the CAISO should propose updated BPM language in the DFP to further clarify the expectation related to the term “available” to set clearer expectations related to the telemetered SOC.  This would be responsive stakeholder requests to review the BPM language prior to beginning the BPM process.

In summary, CESA believes CAISO should publish a DFP on June 30^th addressing the following areas:

1. Outage management enhancements (five items listed above).
2. Use of Technical Limitations Not in Market Model NOW to address nonlinearity.
3. BPM language to clarify SOC definition and calculation.     

2. Please provide your organization’s comments on the topics related to Outage Management, particularly on the different means to represent foldback in the near-term and their relationship to availability incentives.

CESA believes that based upon stakeholder comments received on May 23, the use of Technical Limitations Not in Market Model NOW is an appropriate near-term solution for storage operators to reflect nonlinearity because the outage is RAAIM exempt.  The following justify not applying RAAIM during the interim solution because:

1. If the current rates associated with nonlinearity were accurately modeled in the market software, no outage card would be used and there would be no application of RAAIM.
2. The SOC minimum duration rules were established through the CPUC resource adequacy proceedings.  The CPUC’s resource adequacy proceedings are the appropriate venue to modify the minimum capability rules for new storage resources.  It is not appropriate to retroactively change the rules by opportunistically finding a reason to apply a RAAIM penalty.
3. An interim measure that is RAAIM exempt will not create incentives or disincentives regarding battery sizing for online projects that are already meeting the CPUC duration rules.
4. As Vistra demonstrated in its comments, RAAIM would need to be modified since the 17-hour assessment period would inappropriately apply RAAIM beyond the 4-hour duration requirement.
5. Other resources have similar limitations to reaching full Pmax for an extended duration that are not currently or planning to be subject to RAAIM penalties.

3. Please provide your organization’s comments on Uplift & DEB: Insights into Charging Bid Mitigation.

CESA appreciates the data shared by the CAISO regarding mitigation of charging bids.  The data does demonstrate that storage resources are predominantly mitigated during the peak solar generation periods prior to peak net load and that more resources are mitigated during the summer months of July, August and September.  The concern CESA articulated during the Price Formation Enhancements – Rules for Bidding Above the Soft Offer Cap initiative is that mitigation of charging bids may exacerbate storage unavailability during high price conditions. CESA requests that CAISO perform additional analysis to determine if there is a correlation between charging bid mitigation and high price conditions during peak net load periods.

4. Please provide your organization’s comments on the PG&E’s presentation.

CESA appreciated PG&E’s presentation State of Charge (SOC): Market or Physical Parameter?   The presentation facilitated an interesting discussion and highlighted the need for CAISO to holistically review the existing storage model.  CAISO should discuss further FRP’s impact on SOC and evaluate if envelope constraints for imbalance reserves could apply to FRP or if those constraints need to be modified.  CESA also believes the pricing impact of attenuations factors, particularly with regard to opportunity costs calculations, needs to be more broadly discussed.  CESA notes that the imbalance reserve envelope constraints were developed before issues were identified with the price formation of regulation down and regulation up when attenuation factors were added to the SOC constraints. 

5. Please provide any additional comments.

No additional comments. 

1. Please provide a summary of your organization’s comments on the May 28, 2025 working group discussion.

PG&E supports CAISO’s commitment to accurate modeling of resources and their specific limitations. In the near-term, PG&E supports OMS enhancements in combination with Master File parameters, to accurately reflects storage resources’ availability vis a vis “foldback”.  Making these changes will provide CAISO and stakeholders with data and allow for a better understanding of the problem. During this time, PG&E believes it is appropriate for these “foldback” related outages to be exempt from RAAIM penalties.   

PG&E agrees with CAISO’s analysis of charge bid mitigation, but believes that while correct and unavoidable using the current NGR model, such mitigation can lead to unintended reductions of battery availability during stressed conditions.  Modifications to the current NGR model might enable these unintended consequences to be reduced.? 

2. Please provide your organization’s comments on the topics related to Outage Management, particularly on the different means to represent foldback in the near-term and their relationship to availability incentives.

Until we understand the size of the issue, PG&E believes it is appropriate to provide a Nature of Work card that does not require RA substitution or incur RAAIM penalties for indicate to CAISO that a battery has entered or will imminently enter (or exit) a “foldback range” in which the battery cannot be operated per its master file ramp rate and operating range parameters.  However, PG&E’s primary rationales for supporting this reporting mechanism are that no alternative can be developed in the near term, and that the division of responsibility for real time SOC has not been sufficiently clarified to assign costs in a way that is sure to be fair and correct.  Thus, PG&E believes that the OMS mechanism for protecting batteries from “market model risk” should only be a bridging mechanism, with a sunset date tied to CAISO commitments to develop a better solution through modified modeling of NGR in the markets. 

There are several additional complexities associated with use of OMS as a bridging mechanism to protect batteries from unwarranted penalties, which PG&E believes should be addressed in a draft proposal: 

1. PG&E supports the concept of adding the parameters that determine whether a battery is in a foldback range, and the resulting ramp rates in these ranges, to the Master File.  Having the parameters there will also greatly improve the data analytics capabilities of CAISO and DMM in determining the effectiveness of the OMS card approach. 

2. Entering and exiting the foldback range are not discrete state changes, and the procedures for entering the OMS nature of work card need to be clarified: i.e., should the card be submitted when a battery is close to entering foldback range, already in foldback range, or perhaps on a routine basis to cover future intervals when the risk of entering foldback is high but not a certainty?  Similar questions arise for end dating such a card, unless CAISO chooses to take responsibility for moving batteries out of their foldback ranges. 

3. Assuming that a clear procedure for submitting the Nature of Work card is defined, PG&E believes the OMS data pertaining to this card should be collected by CAISO and DMM to perform aggregate analysis regarding the effectiveness and possible efficiency losses due to the procedure, and also to provide clear information to all market participants as to whether the problem is universal, widespread, or limited to only a few batteries or periods of time. 

4. Finally, RAAIM penalties aside, it seems obvious that the bridging solution to this problem should not result in a loss of RA to the CAISO system that could result in changes to planning reserve margins or system failures of the daily resource sufficiency tests.  Some tolerances should be defined for the upper and lower SOC thresholds such that within these tolerances, capacity calculations are unaffected and no RAAIM penalties are incurred. 

5. However, if “foldback range” takes some substantial percentage of a battery’s SOC (e.g., 20%), foldback should be treated differently, at the sunset of the proposed bridging solution, and potentially be subject to RAAIM, simply because it would in fact require procurement of substitute capacity under stressed conditions. 

3. Please provide your organization’s comments on Uplift & DEB: Insights into Charging Bid Mitigation.

PG&E understands that the existing NGR model does not allow charging and discharging bids to be mitigated separately, because the existing NGR model is based on a single monotonic bid curve from pmin to pmax.  This bid format implies that a bid constructed to indicate high willingness to charge and high unwillingness to discharge in a current interval in order to capture an even higher discharge value in a later interval (whether due to an existing day ahead award or an anticipated real time award) may be mitigated to a price below the current clearing price, so that the mitigated portion of the charging segment of the battery’s bid does not clear.  PG&E hypothesizes that this outcome will be rare or nonexistent in the day ahead market, in which the CAISO’s market optimization would see the higher value of discharge in the later hour and hence charge in an earlier period if needed to minimize total day ahead costs.  In real time the optimization horizon is short enough that the issue should be a rare one, but the claim has been made that some batteries do see such mitigation preventing charging frequently and with high costs to the batteries due to forced buyback of day ahead discharge awards.  PG&E suggests that the Negotiated DEB, based on documentation of such losses, would be one appropriate method to address such frequent over-mitigation.  Another approach would be to define a DEB that allowed a higher charging bid during the solar hours, when battery discharge would be unlikely except in case of contingencies in any case, and hence less susceptible to the exercise of market power. 

4. Please provide your organization’s comments on the PG&E’s presentation.

None.

5. Please provide any additional comments.

1. Please provide a summary of your organization’s comments on the May 28, 2025 working group discussion.

PGE has questions regarding the feasibility of using outage cards to represent nonlinearity (foldback) BESS resource characteristics and requests additional conversation on the operational feasibility of this proposal.

PGE supports modifications to charging bid modification and DEB design, especially as EIM entities increasingly participate BESS in the RT market. PGE would like a mechanism to account for price deviations between RT and DA.

2. Please provide your organization’s comments on the topics related to Outage Management, particularly on the different means to represent foldback in the near-term and their relationship to availability incentives.

1. PGE requests additional detail on the suitability of using outage cards to communicate foldback due to the compatibility issues with the RT market operations' 4.5-hour lookahead. PGE believes that master file updates are the optimal near and long-term solution for representing nonlinearity and foldback.

2. Currently, BESS outage reporting is complex, requiring multiple outage cards for different characteristics (MWh, SOC, Pmax, Lmax, etc.). This is more complex than traditional resources due to BESS's unique characteristics and additional data fields.

1. 1. When submitting an outage card for a battery, all details must be included even if only one parameter has changed. For example, if a few cells are lost, affecting only the State of Charge capacity (EMax), operators still need to fill out the entire outage card, including PMax, PMin, LMax, LMin, EMax, and EMin. Similarly, when losing an inverter that impacts P/L figures, all other values must be adjusted as well.
   2. PGE would like to discuss enhancements to allow NULL value submissions and overlapping outages. These changes would enable more precise reporting of individual condition changes without necessitating updates to unaffected parameters. For instance, operators could submit one outage to reflect a single condition change and later submit a second outage to represent a different condition.

These improvements could streamline the outage management process for BESS resources, allowing for more accurate and efficient reporting of various outage conditions.

3. Please provide your organization’s comments on Uplift & DEB: Insights into Charging Bid Mitigation.

PGE supports modifications to the existing charging bid mitigation design. PGE supports improvements to bid range flexibility via mechanisms including improved price-based opportunity cost design that includes an intra-day opportunity cost component to reflect real time price deviations.

4. Please provide your organization’s comments on the PG&E’s presentation.

PGE thanks PG&E for the comprehensive presentation and is interested in continued conversation around (1) the role of market vs physical SOC, (2) envelope constraints, (3) the SOC bidding model, and (4) options for evolving the NGR model to incorporate RT ramp rates.

5. Please provide any additional comments.

Since bidding batteries into the EIM, PGE has sought to balance both spinning reserve requirements and BESS participation in the RT market. The current market design allows participants to hold out power (MWs) but not charge (MWh) for spinning reserves.

Using a 200MW BESS resource as an example:

• A market participant holds back 50 MW spinning reserves on the battery
  • Thus, the market optimization will dispatch no more than 150 MWs
• However, the market may still dispatch resource to 0 or minimum SOC
  • This results in no remaining SOC available to utilize spinning reserves
  • Occurs even when using an end-of-hour SOC constraint (constraint doesn’t apply to middle of hour)

In addition, PGE lacks clarity on the suitability of other methods to impose hard limits on reserving charge (MWh), including the use of outage cards or a bid SOC limit. PGE is uncertain of the market’s response should PGE need to call on the spinning reserves to the point where SOC drops below the outage limit. Therefore, PGE would like to introduce the Spinning Reserves issue into the storage design working group scope to discuss design options and improvements.

1. Please provide a summary of your organization’s comments on the May 28, 2025 working group discussion.

SDG&E appreciates the opportunity to provide comments on the May 28 stakeholder meeting for the Storage Design and Modeling initiative. As a general matter, SDG&E supports CAISO’s proposed plan of action for this initiative as outlined in the 5/28 presentation, particularly the near-term BPM update, implementation of OMS enhancements, and continuation of the battery State of Charge (SOC) clarification discussion under the "SOC Management Topics" grouping. The overall initiative timeline allows for concurrent discussions, ensuring each topic area can be addressed within a reasonable timeframe, and time-sensitive issues can be accelerated for implementation. The pace CAISO intends to conduct this initiative seems to be workable, but depending on implementation feasibility timing, there may be topics where it would be appropriate for CAISO to moderate the pace of issue and proposal development to maximize stakeholder engagement. The Storage Modeling and Design initiative consolidates several inter-related topics that impact storage resources, and given the interconnectedness of issues, a slightly slower process that enables participants to fully engage in the discussion of issues and development of solutions may be preferable when there are periods with overlapping on proposals for each track and implementation may not be feasible for some time.

SDG&E also encourages CAISO to provide additional detail on the timeline and process for next steps on the OMS enhancements. These enhancements would improve operations for storage resources and it appears that CAISO will be prioritizing implementation of those changes in this initiative. However, SDG&E would like to understand how DAME/EDAM implementation efforts may impact the implementation timing of OMS enhancements, if at all.

2. Please provide your organization’s comments on the topics related to Outage Management, particularly on the different means to represent foldback in the near-term and their relationship to availability incentives.

SDG&E reiterates its position that use of the RAAIM exempt "Technical Limitations Not in Market Model" NOW card is the most appropriate interim solution to use in the case of Nonlinearity/Foldback. While outage card usage may present a feasible near-term fix, it remains critical to move expeditiously to develop a long-term, market-based solution. To the extent that there are concerns over misuse of this outage card, CAISO should consider what additional information, if any, may be needed to ensure there is sufficient data to allow for CAISO to monitor and track the use of this NOW to reflect nonlinearity and include that in the next iteration of the proposal.

3. Please provide your organization’s comments on Uplift & DEB: Insights into Charging Bid Mitigation.

SDG&E thanks CAISO for the data-based insights into the frequency of concerning events, which are important to better target efforts and attention during the initiative. Due to the demonstrated infrequency of instances of charging bid mitigation, SDG&E does not believe that further exploration of this topic should overtake other priorities.

4. Please provide your organization’s comments on the PG&E’s presentation.

SDG&E thanks PG&E for their work and the thorough discussion of representation of SOC in the market. The issues raised in the presentation highlight the need for longer-term changes to the modeling and uplift paradigm for storage resources. While SOC should ideally reflect the true physical availability of storage resources, challenges with market optimization require resources to shape their dispatch to meet schedules later in the day. Durable solutions to storage optimization and development of BCR procedures will require further consideration of these issues, highlighting the importance of this initiative and discussion of broader policy ideas prior to development of any concrete solutions.

5. Please provide any additional comments.

1. Please provide a summary of your organization’s comments on the May 28, 2025 working group discussion.

Southern California Edison (SCE) comments can be viewed under the subsequent questions.

2. Please provide your organization’s comments on the topics related to Outage Management, particularly on the different means to represent foldback in the near-term and their relationship to availability incentives.

SCE’s position regarding Outage Management and foldback representation remains unchanged since the last comment period.[1]

SCE reiterates that the CAISO tariff and BPM for Outage Management should provide detailed requirements for outage reporting, including the appropriate method for reflecting foldback/non-linearity (i.e., Power Availability and Load Max evolving as a function of the resource SOC). Providing detailed requirements will ensure consistency across the battery fleet, support reliability, and allow for better market optimization.  

SCE supports outage reporting guidelines that represent the true availability of the battery. To the extent that a battery has energy capacity available, but it can only be accessed at a lower power rating, guidelines should require the battery to represent the actual power rating, as soon as possible through an update of the Resource Availability and Load Max. To the extent that energy capacity is stranded and cannot be accessed at any power rating, guidelines should require the battery to represent the updated minimum or maximum SOC. 

While SCE supports outage reporting guidelines that reflect the actual operational characteristics of the battery, we acknowledge that CAISO’s current methodology for calculating RAAIM charges would not appropriately penalize a battery for truly stranded energy capacity that is represented through an update of the min/max SOC attributes. While a battery that cannot support its full NQC power rating for 4-hour would fail to meet the CPUC’s RA criteria, there is currently no mechanism to assess that penalty through CAISO’s RAAIM process. As such, CAISO may consider adjusting the RAAIM calculation for batteries to also include an energy capacity performance metric.

[1]SCE Comments on CAISO Storage Design and Modeling Issue Paper and Straw Proposal, May 23, 2025, https://stakeholdercenter.caiso.com/Comments/AllComments/a278055e-4347-4ae8-bfd5-abdc49e61dad#org-d3c6e5fb-43f1-4017-8a38-31bef59d23fc 

3. Please provide your organization’s comments on Uplift & DEB: Insights into Charging Bid Mitigation.

SCE does not have any comments at this time.

4. Please provide your organization’s comments on the PG&E’s presentation.

SCE does not have any comments at this time.

5. Please provide any additional comments.

SCE does not have any comments at this time.

1. Please provide a summary of your organization’s comments on the May 28, 2025 working group discussion.

The Salt River Project Agriculture Improvement and Power District (SRP) appreciates the opportunity to provide feedback on the recent working group discussion regarding the Storage Design and Modeling initiative. SRP conditionally supports using the Outage Management System as a temporary solution while the Master File process is updated to handle battery foldback characteristics but seeks clarity on the required modifications and their timelines. SRP also requests a side-by-side comparison of three interim approaches: Outage Management, Nature of Work, and Dynamic Limits, including necessary changes and implementation timelines. Should the interim solutions require significant time, SRP suggests focusing on updating the Master File process instead. Additionally, SRP requests more detailed bid mitigation data, including price impacts, bid magnitudes, and breakdowns by DEB-setting methods for storage resources.

2. Please provide your organization’s comments on the topics related to Outage Management, particularly on the different means to represent foldback in the near-term and their relationship to availability incentives.

SRP conditionally supports using the Outage Management System as an interim solution until the necessary adjustments can be made to the Master File process to accommodate battery foldback characteristics. However, SRP would like clarification of what kind of modifications to the existing process would be required to implement successfully and how long those modifications would take. For example, it is currently not possible to include SOC conditions in outage cards; how long would it take to modify the outage process to accommodate this change? SRP would like to see a clear side by side comparison of the various interim remediation suggestions: Outage Management system approach, Nature of Work approach and Dynamic Limits approach, along with the required modifications and expected modification timeline for each in order to effectively assess them. If the expected modification timelines are excessive, time might be better spent updating the Master File Process as a long-term solution. Also, examples regarding the impact of RAAIM on the various proposed solutions would be useful.

SRP agrees that any updates to current systems need to be tested and vetted through market simulation.

3. Please provide your organization’s comments on Uplift & DEB: Insights into Charging Bid Mitigation.

It would be useful to get more insight into the conditions associated with mitigation rather than just counts. While hourly percentages were useful, it would also be useful to understand the typical prices prevailing during mitigation as well as the magnitude of the bid mitigation. Similarly, it would be beneficial to know if the mitigated bids were unusually high compared to their peers.  Also, as there are several methods for setting DEBs for storage resources, it would be useful to see the mitigation frequency broken out and grouped by which approach an entity is using.

4. Please provide your organization’s comments on the PG&E’s presentation.

N/A

5. Please provide any additional comments.

The expected implementation timeline and process should be included in the next revision of the Straw Proposal.

1. Please provide a summary of your organization’s comments on the May 28, 2025 working group discussion.

WPTF supports the use of outage cards to manage foldback in the near term and strongly urges CAISO to allow use of the Technical Limitations Not in Market Model nature-of-work (NOW) with RAAIM exemption. Applying RAAIM penalties in cases where limitations are not represented in the market provides no meaningful incentive and risks imposing unnecessary costs on ratepayers. Additionally, WPTF is concerned that the current approach to mitigating charging bids could reduce storage charging and limit availability during critical peak periods. While the current impact may be small, the growing storage fleet makes it important to address this issue proactively to maintain system reliability.

2. Please provide your organization’s comments on the topics related to Outage Management, particularly on the different means to represent foldback in the near-term and their relationship to availability incentives.

WPTF continues to support the use of outage cards as a practical near-term mechanism to manage foldback. While we appreciate CAISO’s ongoing work with stakeholders to develop a durable, market-based solution that includes changes to the Masterfile and market model, it is critical that the interim approach remains practical, efficient, and avoids unintended consequences.

Regarding the appropriate nature of work (NOW) to reflect these conditions, we strongly urge CAISO to proceed with using the Technical Limitations Not in Market Model NOW, which provides for Resource Adequacy Availability Incentive Mechanism (RAAIM) exemption. As discussed in stakeholder meetings and included in our previous comments, there are multiple valid reasons why such conditions warrant exemption from RAAIM penalties:

• These limitations are not modeled in the market and cannot be forecasted or controlled through market behavior
• Applying RAAIM penalties under these circumstances does not serve as a meaningful or effective incentive for improved performance
• Exposing resources to penalties for conditions outside their control could impose substantial costs with no reliability or efficiency benefit, costs that will ultimately be borne by ratepayers

Given this is a temporary solution, it is inappropriate to impose financial consequences. CAISO should move forward promptly with the RAAIM-exempt NOW card to ensure fairness and avoid undermining the intent of RAAIM during this transitional period.

3. Please provide your organization’s comments on Uplift & DEB: Insights into Charging Bid Mitigation.

WPTF appreciates the thoughtful analysis CAISO provided on the mitigation of charging bids. The data clearly shows that charging bid mitigation occurs most frequently during the midday and summer months, precisely the times when storage resources should be charging in preparation for discharging during peak net load hours.

Mitigating charging bids during these critical windows could inadvertently reduce the availability of storage resources to support grid reliability during evening peaks. While we acknowledge that the current overall MW impact may be modest, the energy storage fleet is rapidly expanding. If left unaddressed, this issue could become more pronounced and lead to missed reliability opportunities or increased reliance on more costly alternatives.

We recommend that CAISO explore options to refine its mitigation framework for charging bids, ensuring it does not block storage resources from being used in a manner that supports grid needs.

4. Please provide your organization’s comments on the PG&E’s presentation.

No comments at this time.

5. Please provide any additional comments.