Arizona Now Among the Top Three States with Largest Capacity of Utility-Scale Battery Storage Systems

Phoenix, Ariz.- Utility-scale battery storage deployments in Arizona reached record high levels during the April to June quarter this year, breaking into the top three states with the most Battery Energy Storage Systems (BESS) according to the latest quarterly joint report released by Wood Mackenzie Power & Renewables and the American Clean Power Association. BESS systems help balance energy supply and demand by storing excess solar power for later use when the sun goes down, further adding more power to Arizona's electric grid when it is needed most.

"To truly maximize the benefits of Arizona's abundant yet intermittent solar resources, we must pair them with large-scale battery storage systems," said Vice Chair Nick Myers. "Adding significant storage capacity is critical to maintaining a reliable and resilient grid. Battery storage not only supports grid stability, it ensures that renewable energy is available into the evening when the sun isn't shining."

Arizona has nearly 3,900 megawatts of operational Battery Energy Storage Systems (BESS) as of May 2025, with an additional 3,807 megawatts planned to come online by 2026, according to the Energy Information Administration. California, Texas and Arizona accounted for 75% of utility-scale BESS capacity, WoodMac & ACP reports. Industry experts say Arizona's rise in utility-scale storage development shows the Grand Canyon state's constructive attitude to achieve grid reliability. With the rapid pace of residential, commercial, and manufacturing companies moving to Arizona, the state is meeting high power demands with its "all of the above" approach, embracing both traditional thermal generation, and renewable generation sources where financially viable.

"While Arizona's energy landscape continues to evolve, our regulatory laws remain stagnant," said Chair Kevin Thompson. "The statute which gives the Commission the authority to regulate power plants hasn't been significantly updated since 1971, long before the adoption of renewables and new technologies like battery storage. That means the Commission has little authority to regulate these non-thermal sources the same as traditional thermal plants like natural gas and coal. I hope policymakers will continue to look at updating our statutes so that all generation sources are truly treated the same and environmental and local community considerations are equally evaluated for all generation types."

Senate Bill 1538, a bill that passed the Arizona legislature earlier this year, would have added non-thermal generation (renewables) to the Commission's jurisdiction; however, it was vetoed by the Governor. The Commission's narrow regulatory role over non-thermal sources like BESS systems includes limited Line Siting approval for transmission-related infrastructure necessary for the project's interconnection to the energy grid and approval of requests to recover costs of the battery storage systems. Zoning decisions and approvals of renewable generation source projects are made at the local government level.

"Battery energy storage systems, paired with utility-scale solar, continue to be a viable option in Arizona's 'all of the above' approach to maintain grid stability for residents and to meet tomorrow's demands," said Commissioner René Lopez. "As battery technology advances, I believe such systems will be an integral part of Arizona's long-term energy assets."