Battery storage systems are growing rapidly. The largest battery storage facility in the world, located along Monterey Bay, California, has completed an expansion, showing that storage systems can exist on a gigantic scale — and are easily expandable.

Moss Landing Energy Storage Facility, owned by Vistra Corp. of Texas, added 100 megawatts to the 300 megawatts of capacity that went online in December, for a total of 400 megawatts. The lithium-ion batteries can run for up to four hours on a charge, which translates to 1,600 megawatt-hours. The initial project and expansion operate under an agreement with Pacific Gas & Electric.

California was already leading the nation with 1,438 megawatts of utility-scale battery storage capacity as of June, as much as the next 10 states combined, according to federal energy data.

“Essentially that battery is able to operate like a natural gas power plant for four hours,” said Joshua Rhodes, an energy researcher at the University of Texas at Austin. “In a place like California, that’s really important because of how much solar California has, and the sun goes down every day. The plant is able to provide a lot of support to the grid to help it transition from its daytime solar into its night usage of other power plants.”

Read more: