Any one of these projects would have been the largest battery storage facility ever built. Combined, they amount to 15 percent of the battery storage installed planet-wide last year.

The new battery projects were commissioned in response to a fossil-fuel disaster—the natural gas leak at Aliso Canyon, near the Los Angeles neighborhood of Porter Ranch. It released thousands of tons of methane into the air before it was sealed last February.

In its wake, Southern California Edison (SCE) rushed to deploy energy storage deals to alleviate the risk of winter blackouts. There wasn't any time to waste: All of the projects rolling out this week were completed within 6 months, an unprecedented feat. Tesla moved particularly nimbly, completing in just three months a project that in the past would have taken years.

The battery storage industry—a key part of the plan if wind and solar power are to ever dominate the grid—is less than a decade old and still relatively small. Until recently, batteries were many times more expensive than natural gas "peaker" plants that fire up to meet surging demand in the evening and morning hours.