California’s first grid-connected large solar-battery microgrid went live last week after years of work by Cal Poly Humboldt’s Schatz Center, the Redwood Coast Energy Authority, Pacific Gas & Electric, and others.   

This $11 million front-of-the-meter independent microgrid is comprised of a 2.2 megawatt solar array and 2 MW from three Tesla mega batteries capable of 9 MWh of output. During outages on lines that bring in outside electricity, the local system will be islanded to keep electricity flowing to the Humboldt County airport, the U.S. Coast Guard Air Station, which patrols 250 miles of coastline from the borders of Sonoma County to Oregon, and some small facilities in the fairly remote North Coast.

Redwood Coast Energy Authority’s microgrid “is really a lifeline for our community,” Peter Lehman, founding director of the Schatz Center and project lead, told Current. The region is seismically active, has been inundated by major floods, faces wildfire threats from the surrounding forests, and is accessible by only two major highways—US 101, which runs north to south, and State Route 299, which runs east to west.

When the community is not subjected to power outages, the microgrid supplies energy to the Redwood Coast community aggregator and is sold into the California Independent System Operator’s market. It is the first renewable microgrid to participate in CAISO’s day ahead, real time and ancillary services markets.

Bidding into the ancillary services market, which when called on requires a response within four seconds, is “lucrative,” Lehman said. The payments will help the Redwood Coast Energy Authority recoup its $6 million investment in the microgrid. Another $5 million grant was provided by the California Energy Commission. 

“The Redwood Coast Airport Microgrid has ushered in a new and exciting era for the electric grid in California,” according to Lehman. It is a “role model to communities across the state who are striving to green their energy supply and bolster their resilience in the face of climate change.” 

The Schatz Center and the Redwood Coast worked with PG&E to develop the first tariff to allow the front-of-the-meter system to interconnect and flow over the utility’s distribution lines. In addition, Redwood Coast built a 300 kW behind-the-meter solar array that supplies the county airport, which also required an interconnection agreement with PG&E. The aggregator leases the land for its 300 kW solar panels from the county and payments are made with green electricity.

The Redwood Coast microgrid “represents the culmination of many years of research, innovation, and collaboration by the world’s leading microgrid experts,” stated Jason Glickman, PG&E executive vice president.

It “has informed meaningful technical and policy innovations including the development of the Community Microgrid Enablement Tariff and PG&E’s Community Microgrid Enablement Program,” added utility spokesperson Paul Doherty.

Other partners in the new renewable microgrid include the County of Humboldt, TRC, The Energy Authority, Tesla, Inc., and Schweitzer Engineering Labs.

Blue Lake Rancheria microgrid

The is the second community microgrid in Humboldt County. The first one is the Blue Lake Rancheria, a 420 kW solar array and 500 kW, 950 kWh battery facility, and 1 MW of polluting diesel backup. It was built in 2017 and serves tribal government facilities. Two years later, the battery was expanded to 1,150 kW and 1,950 kWh.

Power to the North Coast power is also protected by PG&E’s 163 MW gas power plant at the shuttered fossil plant, which harmed the marine ecosystem because it used large quantities of seawater to cool spinning generators. PG&E agreed in 2020 to reconfigure the replacement plant installed in 2010, which includes diesel backup, so it can be islanded and keep power flowing to 20 North Coast cities. It, along with the new large renewable microgrid, allow 93% of the community to continue to receive power when outside power that serves the area is cut off.

If significant offshore wind development occurs off the Humboldt coast as anticipated, it will turn the struggling region into an energy hub. The federal Bureau of Ocean Management is planning to auction leases this September for 3 MW. Another 1.5 MW of leases will be issued for wind turbines off Morro Bay’s coast at the same time.