The Borrego Springs microgrid allowed SDG&E to avoid what would have otherwise meant several hours of no power for 2,800 customers.
During nine hours, the microgrid managed power from onsite energy, energy storage and NRG Energy’s nearby 26-MW Borrego Solar to ensure that customers kept their lights on.
The utility said that the event may have marked the first time a U.S. microgrid leveraged renewable energy to power an entire community.
“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,” said Dave Geier, SDG&E’s vice president of electric transmission and system engineering.
Earlier, lightning had damaged a transmission line that usually feeds the community. SDG&E crews needed to replace or repair three transmission poles, which would usually require a 10-hour sustained outage to all of Borrego Springs.
However, SDG&E was able to call on the Borrego Springs microgrid and avoid shutting off the power.
The grid-connected microgrid uses advanced technologies – including local power generation, energy storage, and automated switching – to create a more resilient local grid. It has the ability to disconnect or ‘island’ from the larger grid and function independently during emergencies.
SDG&E reported that it seamlessly switched over to the microgrid to power the entire community at 8:45 a.m. on May 21, allowing the maintenance work to begin. The microgrid generated the majority of power during this time from the Borrego Solar facility.
Batteries and traditional distributed generation filled in gaps created by the intermittent solar facility. The microgrid uses advanced computer software and automated switching to ensure the system accounted for solar fluctuations in real time.
This innovative network of resources kept a steady supply of power flowing to the community throughout the day. At 5:30 p.m., SDG&E completed the repairs and switched the town back to the main grid.
So rather than having an extended, nine-hour outage, customers experienced a planned outage of less than 10 minutes as they were switched back from the microgrid to the repaired transmission feed.
“The microgrid was really a crucial tool during this maintenance,” said Linda Haddock, executive director of the Borrego Springs Chamber of Commerce. “This innovative project provided electricity to our residents and kept the town running all day. Residents were also pleased that the Borrego Solar facility was used to support this effort. It’s great to see all these local, sustainable resources being put back into the community to truly make a difference in the lives of our residents in Borrego Springs.”
Using renewable energy to energize Borrego Springs was one of the main goals of a $5 million grant the California Energy Commission recently awarded to SDG&E. Because of the funding, the microgrid can connect to the Borrego Solar facility, making this one of the nation’s largest microgrids that can operate solely on renewable energy.
In addition to bringing in more clean power, the funding is being used to increase the size of the microgrid, so that it can serve more customers.
SDG&E’s success during the outage is the first step in implementing the CEC’s grant. SDG&E plans to incorporate additional advanced computer software and sensors to enhance the microgrid. The innovations will broaden the microgrid’s use of renewable energy to power the entire community and allow this type of outage response to become routine and standardized.
The utility expects to make the physical improvements to the microgrid by mid-2016.
In 2008, the U.S. Department of Energy granted the utility $8 million to launch the microgrid.
Read about other successful microgrid projects by subscribing to our Microgrid Knowledge newsletter. It’s free.