Sunrun says home batteries sent a record 745 megawatts (MW) to California’s grid on Tuesday, October 6, during an October heat wave. Tesla’s Powerwalls made up most of it. Tesla says more than 85,000 Powerwall owners in California sent over 600 MW, and it called the event “a new record for the largest Powerwall VPP event.” VPP means virtual power plant: many home batteries that act together.
What happened
The California Energy Commission and the state’s utilities asked for the power. A day earlier, on October 5, the same programs delivered 669 MW. October 5 was the first event this year in which two state programs, Demand Side Grid Support and the Emergency Load Reduction Program, dispatched at once across every participating utility area. The new record tops the 580 MW set in September.
Sunrun says it has more than 120,000 home batteries enrolled in California grid programs, and that 745 MW could power every household in San Francisco and San Jose combined at peak hours. Sunrun chief executive Mary Powell said “customers are being compensated for helping strengthen grid reliability.”
What the number does not show
Both companies report only megawatts. A megawatt figure shows how much power flowed at the peak, not how long it lasted, so the total energy delivered is not clear from their announcements.
What is next
A Google-funded project with PG&E near San Jose plans to enroll nearly 21,000 devices from Tesla and Everyday Electric, with first dispatches expected this month. The Tesla and Everyday Electric part is under a non-binding letter of intent, so it is not a firm commitment yet.
Our take: the record shows home batteries can work as a grid tool when a state asks them to, and owners are being paid to take part. It is still the companies’ own figure from one short event during a heat wave. The more useful numbers would be hours of power delivered and how often it can be repeated. Tesla reports third-quarter results on October 21, including its energy business: Tesla Sets Its Q3 Earnings Report for October 21.
