“It’s much more than we thought would be likely,” said Colin Cushnie, the utility’s vice president for energy procurement and management. The total is about four times all the storage the company now has in place or under construction, he said.

It is also extremely large relative to an order issued last year by the California Public Utilities Commission that investor-owned utilities install 1,325 megawatts of storage by 2020.

The bidding results indicate that the cost of storage is falling, experts say, although neither the utility nor the companies whose projects were selected would say what price the utility would pay. And the value of storage varies by location, with California an extreme case. Because of wind farms, the state has very cheap energy available at night, some of which now goes to waste.

The alternative, new generators running on natural gas, is particularly expensive in the Los Angeles area because of strict air emissions limits and high land prices. (Batteries take up less space than power plants.)

In addition to conventional batteries, a large slice of the utility’s solicitation was won by Ice Energy, a company that installs rooftop devices that look a bit like air-conditioners but are used to freeze water in 450-gallon pots.