Arizona Utility Makes Biggest U.S. Bet Yet on Energy Storage

Arizona’s Pinnacle West Capital Corp. is kicking off the most ambitious deployment of energy storage ever announced by a U.S. utility.

Pinnacle West’s Arizona Public Service plans to add 850 megawatts of battery storage and at least 100 megawatts of new solar power by 2025, according to a Feb. 21 statement. The company did not say how much the initiative would cost.

The move comes as Arizona regulators have placed a temporary moratorium on building natural gas-fired plants and as falling energy-storage prices have compelled utilities to use batteries to extend output from solar farms after sundown.

Already, solar ...