AriSEIA Submits 2nd Round of Comments on Mesa's BESS Setbacks

City of Mesa
20 E. Main Street
Mesa, AZ 85201
 
RE: Comments on Item 7 of the December 1 Agenda
 
Dear Mayor and Councilmembers,
 
On behalf of the Arizona Solar Energy Industries Association (AriSEIA), I urge you to reject the proposed 1,000 foot setback for battery energy storage systems (BESS) in Agenda Item 7. AriSEIA is Arizona’s solar, storage, and electrification trade association, and we previously submitted detailed BESS comments to the City in our October 15, 2025 letter.
 
A 1,000 foot setback is arbitrary, unsupported by data or national standards, and would function as a de facto moratorium on BESS in Mesa at the very moment when the region is facing record peak demand and rapidly rising electricity bills. Arizona’s three largest utilities have all set new peak demand records in recent summers, and Salt River Project expects continued significant load growth over the coming decade.[1] These conditions require more flexible, dispatchable resources, not fewer.
 
When this ordinance was before the Planning and Zoning Board, the 400 foot setback already under consideration was too large. Every member of the public who testified spoke against it and urged you to follow national standards instead. Yet, staff has proposed increasing the setback to 1,000 feet. That change moves Mesa even further away from evidence based practice.
 
National guidance and emerging practice in other jurisdictions point in a very different direction. The American Planning Association’s Zoning Practice review of BESS ordinances found that BESS specific setbacks in adopted codes are typically in the range of 50 to 150 feet from property lines.[2]
 
In addition, The National Fire Protection Association (NFPA) 855, the national consensus standard for installation of stationary energy storage, and related guidance used by fire professionals recommend a 100 foot separation between large outdoor BESS and nearby buildings or public ways to manage worst case thermal and blast scenarios.[3] Many jurisdictions address BESS separation primarily through adoption of NFPA 855 and the International Fire Code, combined with project specific review by the fire authority that can consider technology type, enclosure design, fire barriers, and egress.
 
Maricopa County provides a good example of this approach. County staff initially proposed a 500 foot separation between BESS and existing off site residences, but after hearing from fire experts and stakeholders, the Planning and Zoning Commission advanced an ordinance that dropped the 500 foot residential separation.[4] In other words, the County chose not to create a second, much larger layer of BESS specific zoning setbacks on top of the fire code.
 
By contrast, a 1,000 foot setback from BESS equipment to homes, churches, and similar uses in Mesa would:
 
• Push viable sites so far from load that projects become infeasible or uneconomic.
• Single out BESS for treatment that is far more restrictive than other critical energy infrastructure, such as substations.
• Effectively ban standalone BESS projects in most of the City while still allowing other, higher risk facilities at much closer distances.
 
Mesa does not need to reinvent the wheel. There are several defensible paths available to the Council that are protective of public safety and aligned with best practice:
 
1.      Follow the Maricopa County model and rely primarily on the fire code.
Mesa can remove the BESS specific separation requirement from the zoning text and allow the adopted fire code, which incorporates NFPA 855 requirements and related standards, to govern separation distances, fire protection features, and emergency response planning, with project specific review by Mesa Fire and Medical.
 
2.      If the Council decides to retain a numeric setback, it should align with national standards.
A maximum of 100 feet from BESS equipment to property lines is consistent with NFPA 855 guidance and with conditions used in Maricopa County approvals. This distance should always be measured from the BESS structure itself and not from the property line of the BESS parcel.
 
3.      If the Council wants an additional margin of comfort, it should not exceed 150 feet.
Buckeye has already adopted a 150 foot standard, based on the Phoenix Regional Standard Operating Procedures for BESS and NFPA guidance.[5] A 150 foot limit would still be conservative relative to many jurisdictions yet it would remain within the range documented by the American Planning Association.
 
Adopting a 1,000 foot setback would place Mesa well outside the mainstream of BESS regulation, chill investment in energy storage, and worsen the very reliability and affordability challenges your residents are already facing. A more measured, standards based approach is both safer and more practical.
 
For these reasons, AriSEIA respectfully asks the Council to reject the proposed 1,000 foot setback in Agenda Item 7, remove the BESS specific separation requirement from the zoning text or, at most, replace it with a setback no greater than 100 to 150 feet that is tied to NFPA 855 and Mesa’s adopted fire code.
 
Thank you for your consideration and for your continued work on policies that keep Mesa safe, reliable, and affordable while enabling clean energy investment.
 
Respectfully,
/s/ Autumn T. Johnson
Executive Director
AriSEIA 
(520) 240-4757
[email protected]

[1] Pinal County, Board of Supervisors meeting, Sept. 10, 2025, available here https://pinalcountyaz.new.swagit.com/videos/355087?ts=230.
Utility Dive. “Arizona utilities hit new peak demand during extreme heat.” July 2023.
Available at: https://www.utilitydive.com/news/arizona-utilities-peak-demand-heat-wave/686198/

[2] American Planning Association. Zoning Practice: Regulating Battery Energy Storage Systems. March 2024.
Available at: https://planning-org-uploaded-media.s3.amazonaws.com/publication/download_pdf/Zoning-Practice-2024-03.pdf

[3] National Fire Protection Association. NFPA 855: Standard for the Installation of Stationary Energy Storage Systems. 2023 edition.
UL. UL 9540A Test Method for Evaluating Thermal Runaway Fire Propagation in Battery Energy Storage Systems.

[4] Maricopa County Planning and Zoning Commission. Public Hearing on Text Amendment TA2024001 (Battery Energy Storage Systems). November 6, 2024.

[5] City of Buckeye. Zoning Code, Article 3: Use Regulations. Battery Energy Storage Systems standards adopted October 21, 2025.