Sunrun has successfully strengthened the stability of Puerto Rico's electricity grid by relying on a "Virtual Power Plant" (VPP) network that includes thousands of home batteries, which were used to support the grid for 18 consecutive days last October.
The virtual power plant technology relies on connecting batteries distributed across thousands of properties and coordinating their operation to act as a unified energy source when needed. According to company data, its network in Puerto Rico now includes nearly 70,000 batteries, capable of providing an average of 45 megawatts (MW) for four hours at a time. This network has been activated more than 60 times since last April, including daily deployments that began on October 13 to combat an unusual heatwave.
Mechanism and Technical Growth
Sunrun's network has seen rapid growth, rising from about 4,000 customers in 2024 to more than 30,000 in 2025, reaching current levels. The company is now the largest energy aggregator within the Customer Battery Energy Sharing (CBES) program in Puerto Rico.
The island's grid operator, LUMA, calls upon CBES program resources when it anticipates that electricity demand or reserve requirements will exceed available generation levels. In this case, companies like Sunrun manage the battery response automatically, allowing stored energy in homes to be discharged to support the public grid.
Why This Development Matters
The importance of this technical solution stems from the significant challenges Puerto Rico faces in the energy sector; residents pay some of the highest electricity prices in the United States, with the average price per kilowatt-hour in August reaching 26.36 cents, compared to an average of 18.16 cents in the United States.
In addition to cost, the island suffers from reliability issues, with the average power outage reaching 36 hours for customers in 2025, a 19% increase from 2024. Virtual power plant technology allows for the utilization of equipment already present in homes to secure energy without waiting for the construction of new power plants. Furthermore, homeowners receive financial compensation for sharing a portion of their battery capacity while retaining enough for personal use as a reserve.
Limitations and Future Challenges
Despite the success achieved, a technical gap remains. Aggregators participating in the program explained in a regulatory report in April that the program was unable to prevent all scheduled power outages in 2025 because some supply gaps exceeded the program's capacity of approximately 50 megawatts for four hours. Participants are currently seeking to register more batteries to increase capacity and cover larger supply gaps.