Key Moments
- Sunrun (NASDAQ:RUN) stock rose 4% Monday morning after a major grid support event in California on September 9.
- More than 140,000 home batteries supplied 580 megawatts of peak power to California’s grid during a heat wave, described as the largest residential distributed power plant event in history.
- A Brattle Group report commissioned by Sunrun and Tesla (NASDAQ:TSLA) found these grid programs could yield up to $206 million in net cost savings to Californians by 2028.
Record-Setting Residential Power Dispatch
Sunrun (NASDAQ:RUN) shares advanced 4% Monday morning after the company, together with Tesla (NASDAQ:TSLA), delivered a large-scale battery dispatch to California’s electricity grid on September 9 during a heat wave. The companies sent 580 megawatts of peak power from residential batteries, which was characterized as the largest residential distributed power plant event ever recorded.
More than 140,000 home battery systems discharged electricity into the statewide grid under severe heat conditions. The combined output matched the capacity of a large power plant and came as elevated temperatures pushed up electricity demand and wholesale energy prices.
Operational Details of the Grid Event
Sunrun and Tesla coordinated the September 9 dispatch at the request of the California Energy Commission and utilities. For a three-hour evening window, participating customers’ home batteries were discharged to support the grid. Of the total 580 megawatts, 517 megawatts came from Tesla Powerwalls, while 63 megawatts came from other battery systems.
Among the 110,000 Powerwalls that took part, 55% are owned and operated by Sunrun. In addition to those units, Sunrun also dispatched more than 30,000 batteries from other manufacturers installed at its customers’ homes.
| Metric | Value / Detail |
|---|---|
| Total peak power dispatched (September 9) | 580 megawatts |
| Power from Tesla Powerwalls | 517 megawatts |
| Power from other batteries | 63 megawatts |
| Number of participating home batteries | More than 140,000 |
| Number of participating Powerwalls | 110,000 |
| Share of Powerwalls owned and operated by Sunrun | 55% |
| Additional Sunrun customer batteries (non-Powerwall) | More than 30,000 |
Statewide Programs and Utility Participation
The coordinated effort operated through two California grid service frameworks: the California Energy Commission’s Demand Side Grid Support program and the California Public Utilities Commission’s Emergency Load Reduction Program. Batteries participating in the September 9 event were distributed across the service territories of all three investor-owned utilities in the state.
Follow-Up Dispatch and Combined Capacity
On the evening of September 10, Southern California Edison requested an additional three-hour dispatch during peak hours. In response, Sunrun and Tesla delivered more than 140 megawatts of battery capacity to the grid. According to the companies, if the September 9 and September 10 dispatches had taken place on the same night, they would have provided over 720 megawatts in a single event.
Projected Economic Impact
A study by The Brattle Group, commissioned by Sunrun and Tesla, concluded that these demand-side programs have the potential to generate up to $206 million in net cost savings for Californians by 2028.
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