On July 29, 2025, a 700MW fleet of household battery systems, including Tesla Powerwalls, was tested as a virtual power plant (VPP) in California, discharging 535MW into GO15 member CAISO’s grid during the 7pm-9pm peak.
Tesla and Sunrun, a solar and storage leasing company, were the two biggest aggregators involved in the operation.
The test analysis showed a significant reduction in net load, mitigating California’s Duck Curve and evening peak strain. Enrolled in the California Energy Commission’s Demand-Side Grid Support program, the batteries performed consistently, supporting grid reliability amid anticipated heat waves.
The role VPPs could play in mitigating CAISO’s net peak could reduce the need to invest in additional generation capacity and relieve strain on the system associated with the evening load ramp-up.