SAN DIEGO — All the electricity delivered to Borrego Springs during a nearly nine-hour period last month came from a nearby “microgrid,” in what’s believed to be the first time that such a facility powered an entire community in the U.S., according to San Diego Gas & Electric.
The May 21 feat came during planned maintenance on SDG&E’s power grid, when all 2,800 customers in the desert community in northeastern San Diego County were switched over to the microgrid, according to the utility.
SDG&E officials said a significant amount of the power came from the 26- megawatt Borrego Solar facility. Since solar generation fluctuates depending on climatic conditions, batteries and diesel generators were also used.
“SDG&E demonstrated in a real-world situation how we can use innovative technology to create a more resilient and sustainable grid for our customers,” said Dave Geier, the company’s vice president of electric transmission and system engineering.
“Borrego Springs was entirely separated from the main grid, running on the microgrid’s local on-site resources for nine hours as we conducted necessary maintenance,” Geier said. “This ability to operate independently of the grid when necessary is exactly what the microgrid was designed for and the fact that we were able to accomplish this using local renewable energy is an added benefit.”
SDG&E said it employed the Borrego Springs microgrid because the transmission line that usually feeds the community had been damaged by lightning. Crews needed to replace or repair three transmission poles, which would usually require a 10-hour sustained outage to the entire community of Borrego Springs.
The microgrid is connected to the centralized energy grid, but can disconnect and function independently during emergencies, supplying electricity to the local community through its on-site resources.
According to SDG&E, it switched over to the Microgrid to power the entire community at 8:45 a.m. May 21, allowing the maintenance work to begin.
At 5:30 p.m. that day, crews completed the maintenance project and switched the town back to the main grid, during which customers experienced an outage of less than 10 minutes, according to SDG&E.