Utility-scale battery storage installations in Arizona reached new highs during the second quarter of this year, positioning the state among the top three in the United States for Battery Energy Storage Systems (BESS) capacity. This development was highlighted in a recent joint report from Wood Mackenzie Power & Renewables and the American Clean Power Association.
BESS systems store excess solar power generated during daylight hours for use after sunset, helping to stabilize Arizona’s electric grid. “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.”
According to data from the Energy Information Administration, Arizona has about 3,900 megawatts of operational BESS as of May 2025, with plans for an additional 3,807 megawatts by 2026. The combined utility-scale BESS capacity of California, Texas, and Arizona accounts for three-quarters of national capacity. Industry observers note that Arizona’s rapid expansion in battery storage reflects its approach to balancing increased energy demand driven by growth in residential and commercial sectors through a mix of traditional and renewable sources.
Commission Chair Kevin Thompson addressed regulatory challenges facing these technologies: “While Arizona’s energy landscape continues to evolve, our regulatory laws remain stagnant,” he said. “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.”
Earlier this year, Senate Bill 1538 passed through Arizona’s legislature with provisions to expand commission oversight over non-thermal generation such as renewables but was vetoed by the Governor. As it stands now, local governments are responsible for zoning decisions on renewable projects while commission oversight is limited mainly to certain approvals regarding transmission infrastructure and cost recovery requests related to BESS projects.
Commissioner René Lopez emphasized ongoing advances: “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,” he said. “As battery technology advances, I believe such systems will be an integral part of Arizona’s long-term energy assets.”
