US battery storage capacity increased by 52% year over year, to 10.8 GW by the end of Q1

The Electric Reliability Council of Texas footprint added the most capacity in the first quarter, 498.6 MW, ending the three-month period with 3.3 GW, or 30.5% of U.S. capacity. The California Independent System Operator leads the nation with 5.2 GW, or 48.2% of U.S. capacity.

The Western Electricity Coordinating Council added 115 MW, or 16.2% of total U.S installations in Q1. Each of the other regions installed less than 3%.

The largest projects completed in the first quarter were in ERCOT and WECC and included Acciona Energy North America's 190-MW BT Cunningham Storage in Texas, Aypa Power Development's 155.5-MW Wolf Tank Storage facility in Texas and Key Capture Energy's 51.5-MW KCE TX 19 facility and 51.5-MW KCE TX 21 facility, both in Texas.

Others included NextEra Energy Resources' 50-MW Buena Vista Energy Center in New Mexico and Arizona Public Service's 50-MW El Sol battery energy storage system.

If all 3.2 GW of proposed second-quarter additions are completed and connected to the grid, overall battery storage capacity would be about 14 GW in the U.S.

While first-quarter additions shifted to ERCOT, the West is expected to again lead in U.S. capacity additions in the second quarter. Developers in CAISO are expected to add 1.6 GW, or 51.1% of all U.S. planned additions, while WECC is projected to add 1.2 GW, or 38%. ERCOT is proposed to be third in line with 200 MW added, or 6.3% of Q2 additions.

The five largest projects proposed to be completed in the second quarter are in the West: Vistra Energy's 350-MW Moss Landing Energy Storage 3 facility in California; NextEra Energy Resources' 260-MW Sonoran Solar Energy facility in Arizona; DE Shaw Renewable Investments' 150-MW Arroyo Energy Storage facility in New Mexico; and two RWE Clean Energy facilities in California — a 137-MW Fifth Standard Solar PV facility and 131-MW CED Westside Canal Battery Storage facility.

The largest battery storage facility in operation is Florida Power and Light's 409-MW Manatee Energy Storage Center, which started operations in the fourth quarter of 2021.