Sunrun (Nasdaq: RUN) has networked more than 16,200 customers’ solar + storage systems to support California’s electrical grid during the summer months.

Sunrun’s CalReady virtual power plant will play a key role in supporting California’s grid, providing essential energy to communities when it’s most needed to help cut costs and prevent power outages.

A virtual power plant is a network of decentralized power generating units – such as solar + storage – collectively managed by a central control system to supply power and provide grid services efficiently.

In the summer of 2023, Sunrun’s Peak Power Rewards virtual power plant program delivered up to 32 megawatts of power to Pacific Gas and Electric Company (PG&E) during evening peak hours, thanks to the participation of 8,500 customers and their batteries.

Sunrun expects to roughly double 2023’s capacity and participants for the statewide Demand Side Grid Support virtual power plant program this summer.

The California Energy Commission runs the Demand Side Grid Support program, which is a key part of the state’s Strategic Reliability Reserve. This initiative helps increase energy supplies during challenging times like heat waves, wildfires, and other extreme events. Thanks to the efforts of aggregators who enroll tens of thousands of batteries, the program plays a crucial role in stabilizing the grid and reducing the risk of rolling blackouts.

Sunrun, as the largest participant in the Demand Side Grid Support program, will handle the monitoring and dispatching of enrolled customers’ batteries. Those who join the CalReady program through Sunrun will receive compensation for sharing their stored solar energy with the grid while Sunrun takes care of all the dispatching details.

Sunrun CEO Mary Powell said that “a typical customer won’t even notice that they’re sharing their stored power to bolster the grid while getting compensated for doing so.”

CalReady will support California’s grid every day from 4 to 9 pm, from May through October, when energy demand peaks and the grid is most susceptible to outages. Sunrun will ensure that customers’ batteries always maintain a minimum backup reserve of 20% to keep their homes powered during local outages.

Chris Rauscher, Sunrun’s head of grid services, explained:

Just like how a centralized fossil fuel power plant is controlled and dispatched by a single entity, so too is Sunrun’s CalReady virtual power plant – making it a powerful contributor to California’s grid. Because CalReady is a distributed resource spread across households statewide, it’s more resilient and adaptable when compared to a physical power plant.

Throughout the five-month program, the California Energy Commission may tap into Sunrun’s enrolled solar + storage systems up to 35 times to provide extra energy to the grid. Sunrun’s CalReady program enrollment is still open, and participation is expected to increase.

Sunrun’s Q1 results, released yesterday, reported a significant jump in storage attachment rates – reaching 50% on installations, up from 15% in the same period last year. The company installed 207.2 megawatt-hours during the quarter.

To date, Sunrun has installed over 102,000 solar and storage systems, representing more than 1.5 gigawatt hours of stored energy capacity.