Giant Batteries Are Transforming the Way the U.S. Uses Electricity

California draws more electricity from the sun than any other state. It also has a timing problem: Solar power is plentiful during the day but disappears by evening, just as people get home from work and electricity demand spikes. To fill the gap, power companies typically burn more fossil fuels like natural gas.

That’s now changing. Since 2020, California has installed more giant batteries than anywhere in the world apart from China. They can soak up excess solar power during the day and store it for use when it gets...