SDG&E to Create One of Largest Renewable Energy Microgrids in the US

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San Diego Gas & Electric plans to create one of the largest renewable energy microgrids in the United States with the help of a $5 million state grant it received earlier this month.

The utility will use the funds to link its Borrego Springs Microgrid to a nearby 26-MW solar photovoltaic plant developed by NRG Energy.

SDG&E won the grant through a $27.3 million solicitation issued by the California Energy Commission for microgrids and electric vehicle charging. It was the only investor-owned utility among ten winners.

The Borrego Springs microgrid, built with $10 million in state and federal funds, now serves about 1,000 customers, but will be expanded to 2,800 customers as part of the project.

North of San Diego, Borrego Springs is somewhat isolated from the main grid, fed by a single sub-transmission line. SDG&E installed the 4-MW microgrid to improve reliability.

The community already has extensive roof-top solar; the islandable microgrid also now uses batteries, diesel generators and automated switching to ensure reliability.

The solar plant will provide enough energy to power the town during the day. Large batteries will store the solar energy to provide power when the plant’s output is low.

If the batteries exhaust their power, the system can access traditional on-site generation.

SDG&E said that new computer software will ensure that the power flow is consistent and the transitions occur seamlessly.

The Borrego Springs Microgrid, which is often cited as a model of what’s to come as the US develops more local energy, has averted several outages, according to the utility. Because of the project’s success, SDG&E is looking into developing additional microgrids.

The utility expects to complete the Borrego Springs Microgrid expansion by mid-2016. The solar plant went into operation in 2013, selling its output to the utility under a 25-year power purchase agreement.

“This funding will create a true renewable energy microgrid, one that not only bolsters local electric reliability, but does so by using the cleanest resources available. This project combines our core priorities of enhancing reliability, promoting innovation and connecting to more clean energy, and we greatly appreciate the CEC’s support in making this happen,” said James Avery, SDG&E’s senior vice president for power supply.

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Green Energy Corporation, Lockheed Martin, and Oracle were among the contractors that helped SDG&E develop the Borrego Springs Microgrid.

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About Elisa Wood

Elisa Wood is the chief editor of She has been writing about energy for more than three decades for top industry publications. Her work also has been picked up by CNN, the New York Times, Reuters, the Wall Street Journal Online and the Washington Post.


  1. Excellent! And the latest in an expanding list of projects that provides evidence of the future role of microgrids in the new infrastructure paradigm.


  1. […] and California is once again a leading state. The California Energy Commission (CEC) just awarded San Diego Gas & Electric a grant of close to $5 million dollars to expand the Borrego Springs microgrid to be powered by […]

  2. […] The utility also is a leader in microgrid development, and is building one of the US’ largest renewable energy microgrids at Borrego Springs. […]