The Arizona Public Service Company is set to install 850 megawatts of energy storage and at least 100 megawatts of new solar by 2025, according to a Feb. 21 press release.

• The first part of the new plan is upgrading existing solar plants with 200 megawatts of battery storage systems. The utility is partnering with Invenergy to install six of the new battery systems at solar plants in Maricopa County and Yuma by 2020, with the remaining two upgrades to be completed by 2021.
• APS also announced that it will use 150 megawatts of solar-fueled battery storage to meet evening peak demand when the company usually relies on natural gas. The battery storage will come from two projects, a 100-megawatt battery provided by AES, and a 50-megawatt battery by Invenergy. Additional backup natural gas will come from a contract with Calpine for 463 megawatts under a seven-year contract instead of the more traditional 20-year power purchase agreement.
• Finally, the company plans to build an additional 500 megawatts of solar storage and stand-alone battery storage by 2025, starting with a 100-megawatt solar-storage plant for which the utility will issue a request for proposals this summer. In addition, the company is already partnering with Tempe-based First Solar to build a first-of-its-kind 50-megawatt solar-plus-storage project that will be one of the largest in the country when completed in 2021