AriSEIA filed the direct testimony of our two experts today in the Tucson Electric Power rate case. We are focusing on community solar and battery storage programs for residential and commercial customers. The testimony and exhibits exceed 400 pages. You can view the entire filing at the button above. TEP is due to file their response on February 15th.
Arizona Corporation Commission
1200 W. Washington Street
Phoenix, AZ 85007
Re: Arizona Public Service (APS) E-32 L SP Tariff, Docket E-01345A-22-0281
Madam Chair and Commissioners,
Pursuant to Decision No. 78317,1 APS was ordered to engage with stakeholders, namely the Arizona Solar Energy Industries Association (AriSEIA) and the Solar Energy Industries Association (SEIA), to redesign the E-32 L SP (Storage Pilot) rate tariff to increase customer adoption of the 35 MW commercial pilot program. AriSEIA appreciated the opportunity to provide constructive feedback and generally guide the tariff design process towards a solution that creates value for APS and the adopting customers.
Throughout the duration of 2022, AriSEIA met monthly with APS and reiterated that rate optionality and investment certainty are key components of behind-the-meter energy storage adoption as not all customer loads are created equal, and few customers are able to benefit from existing tariffs using 15-minute interval demand charges. To that end, we collaborated with APS on the proposed volumetric, time-of-use (TOU) rate including a substantial differential between on-peak and off-peak rates which de-risks the customer’s energy storage investment in terms of achieving monthly savings while creating grid support during the utility’s coincident peak periods. Our assessment of the new rate tariff is that it will encourage participation in the pilot energy storage program through market-competitive payback opportunities. This rate tariff may also provide a foundation to develop more value-stacking opportunities for utilities such as distributed virtual power plants or similar grid-response programs.
While the proposed E-32 L SP pilot revisions are a significant step in the right direction, we believe that further alignment with APS’ true coincident on-peak demand periods is important to creating an equitable program. To this end, we issued our recommendation to APS to limit the on-peak hours to Monday through Friday in lieu of across all seven (7) days of the week as the weekend load and marginal prices are typically much lower and do not merit the same TOU price differential. We look forward to continuing to work with APS as this program evolves.
Thank you for considering these comments and we encourage you to adopt this rate in the first quarter of 2023 and to continue promoting more grid-interactive programs for customer-sited distributed energy resources.
President, Board of Directors
1 Arizona Corporation Commission, Decision 78317, November 9, 2021, available here https://docket.images.azcc.gov/0000205236.pdf?i=1670984264693.
BEFORE THE ARIZONA CORPORATION COMMISSION
Lea Márquez Peterson – Chairwoman
IN THE MATTER OF THE APPLICATION OF ARIZONA PUBLIC SERVICE COMPANY FOR A HEARING TO DETERMINE THE FAIR VALUE OF THE UTILITY PROPERTY OF THE COMPANY FOR RATEMAKING PURPOSES, TO FIX A JUST AND REASONABLE RATE OF RETURN THEREON, AND TO APPROVE RATE SCHEDULES DESIGNED TO DEVELOP SUCH RETURN.
Docket No. E-01345A-19-0236
Arizona Solar Energy Industries Association (AriSEIA) Comments on Arizona Public Service (APS) Efforts to Comply with Order Relating to Rate Schedule E-32 L Storage Pilot in Decision No. 78317
We appreciate the Commission’s decision to include AriSEIA/SEIA in collaborative discussions with APS on the rate design elements and intended success of the E-32 L Storage Pilot (SP) plan.
The E-32 L SP tariff was established in December 2017 as a result of APS’ previous rate case with the intention to evaluate the opportunity of large-scale, behind-the-meter energy storage solutions as a value-added benefit to the grid while allowing for high demand (as determined by 15-minute interval kilowatt readings) customers to benefit from peak shaving. Due to several issues, including poor rate tariff mechanics and imbalanced Cost of Service (COS) formulas (notably with lower per-kW rates than the non-pilot, base E-32 L rate tariff), the pilot program offering did not facilitate subscription from any customers.
Decision No. 78318 and Current Status
AriSEIA/SEIA offered testimony that the E-32 L SP rate schedule required re-evaluation. The Commission ordered APS to do the following:
Subsequent to the order, APS filed its revised rate tariff on December 1, 2021, and held its first stakeholder engagement meeting on February 23, 2022. AriSEIA/SEIA maintains that while APS is complying with the letter of the order, the spirit of the decision is being left to stakeholders to enforce.
Key Issues on Proposed E-32 L SP Rate Plan and Discussion
It is AriSEIA’s understanding that the intent of this pilot program is to facilitate adoption of energy storage for APS’ large commercial customer class up to 35 megawatts (MW) of installed capacity, and to that end, we submit the following feedback for consideration:
Due to the nature of variability between customer load profiles (predictability of peaks depending on facility type), the economics of energy storage vary significantly from project-to-project. Furthermore, the value proposition (i.e., return on investment), depends on whether or not a customer can monetize federal tax incentives directly. Although pending federal legislation includes a change which provides tax credits to ‘storage only’ projects, the current Internal Revenue Code only allows energy storage customers to claim available tax incentives when the storage systems are charged by solar energy (at least 75%) throughout the operational year. Given that many APS E-32 L customers are tax-exempt and the fact that this tariff is unlikely to support solar projects in conjunction (i.e. tax credits will not be available), we believe it is critical that the tariff be designed in a way that provides sufficient economic incentive to pursue pilot projects for all interested customers.
Energy storage systems represent significant investments and require a precise and reliable method for return on investment. We submit that the spirit of the Order requires that APS demonstrate a thoughtful and comprehensive approach to the design of the E-32 L SP rate tariff, and we recommend an approach that leverages optionality and increased on-peak vs. off-peak differentials.
As it stands, it is AriSEIA’s position that the current E-32 L SP rate plan will not facilitate any adoption toward the cap of 35 MW without substantial changes, and we recommend the Commission direct APS to issue revised rate tariff options that will provide further opportunities for customer adoption.
We thank the Commission and its staff for the opportunity to submit these comments.
Respectfully submitted this 6th day of May, 2022.
/s/ Autumn T. Johnson
Arizona Solar Energy Industries Association (AriSEIA)
/s/ John Mitman
Arizona Solar Energy Industries Association (AriSEIA)
 See APS 2019 Rate Case, Docket No. E-01345A-19-0236, Decision No. 78317, available here https://docket.images.azcc.gov/0000205236.pdf?i=1650001754509.
 See APS 2017 Rate Case, Docket No. E-01345A-16-0036, available here https://edocket.azcc.gov/search/docket-search/item-detail/19348.
 National Renewable Energy Laboratory, Identifying Potential Markets for Behind-the-Meter Battery Energy Storage: A Survey of U.S. Demand Charges, available here https://www.nrel.gov/docs/fy17osti/68963.pdf.
 Southern California Edison, Schedule TOU-8 Time-of-Use - General Service – Large (Option E), available here https://www.sce.com/regulatory/tariff-books/rates-pricing-choices and included as Attachment A.
 National Renewable Energy Laboratory, Storage Futures Study, available here https://www.nrel.gov/analysis/storage-futures.html.
 National Renewable Energy Laboratory, Federal Tax Incentives for Energy Storage Systems, available here https://www.nrel.gov/docs/fy18osti/70384.pdf.
Keep up with the latest solar energy news!