Sunrun customers aided the California grid in summer and fall of 2023 via the Pacific Gas and Electric Company (PG&E) Energy Efficiency Summer Reliability Program, also known as Peak Power Rewards. This residential solar and storage distributed virtual power plant was popular with Sunrun customers, achieving its maximum enrollment of 8,500 customers. It was also a big win for the grid, providing a consistent average of 27 MW of power during evening peak hours for more than 90 consecutive days.
With an instantaneous peak output of nearly 32 megawatts, the program frequently supplied the grid with up to 30 megawatts – sufficient power for more than 20,000 homes.
“The Peak Power Rewards program achieved a customer participation rate and power supply volume that’s never been accomplished before,” said Sunrun CEO Mary Powell. “PG&E was able to confidently rely on the renewing daily resource of Sunrun’s fleet of home solar and storage systems. We are rapidly transitioning to a storage-first company and the results of this partnership highlight the unique capability that distributed power plants provide communities.”
Enrolled battery systems discharged energy back to the grid every day from 7 p.m. to 9 p.m. during the months of August through October, a critical window when energy needs are highest in California. In exchange, customers received an upfront payment of $750 and a free smart thermostat for participating. Batteries enrolled in the program retain enough energy to meet personal, essential needs in the event of a local power outage in their area.
Sunrun managed the participating fleet of home batteries to provide power to PG&E in the same way that a centralized, traditional power plant would. However, Peak Power Rewards was operational within six months of contract signature, a timeframe not possible when building traditional power plants.
Sunrun’s distributed power plant programs use software to manage the discharging of thousands of home batteries onto the grid in coordination with utility needs, requiring no action on the customers’ part.
PG&E has connected nearly 820,000 customers with rooftop solar to the electric grid totaling approximately 8,039 megawatts of capacity. Nearly 75,000 PG&E customers have installed and connected storage systems to the grid in PG&E’s service area as well, totaling more than 670 megawatts of capacity.
“What is happening in California will soon need to be replicated across the country,” Powell said. “Residential solar-plus-storage systems networked together as distributed power plants are answering the demand call by providing flexible, on-demand power stabilization while also guarding against increasing rates.”
“Working together with partners like Sunrun is a win-win-win for our customers, the electric grid and California as a whole. Solar-plus-storage plays a significant role in California’s clean energy future and we’re proud of our customers who are leading the charge with their clean energy adoption,” said Patti Poppe, CEO of PG&E Corporation.
— Solar Builder magazine
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