Tesla and Sunrun’s virtual power plant dispatch record 580 MW to California grid

On September 9, Tesla and Sunrun linked more than 140,000 home batteries into a "virtual power plant" — a network of home batteries acting together like a single power source — and sent a record 580 megawatts to California's grid during a heat wave. About 110,000 of those batteries were Tesla Powerwalls, which supplied 517 MW; the rest came from other battery brands in Sunrun's network. Combined, that's enough power for every household in Sacramento County during peak hours. The next evening, Sunrun sent another 140-plus MW to the grid at Southern California Edison's request.

The batteries were tapped through two existing state programs: the California Energy Commission's Demand Side Grid Support program, which kicks in automatically when wholesale power prices spike, and the California Public Utilities Commission's Emergency Load Reduction Program, which utilities activate directly during extreme demand. Homeowners enrolled in these programs get paid when their batteries send power back to the grid during these events.

This matters because covering short bursts of peak demand usually means building or running expensive power plants that sit unused most of the year. A Brattle Group report cited by Sunrun estimates this kind of battery dispatch could save Californians up to $206 million by 2028. If you already have solar and a home battery, particularly a Tesla Powerwall, this is the kind of event that can put money back in your pocket. Programs and payouts vary elsewhere, so it's worth checking what your own state or utility offers.