A 2020 Nissan Leaf in front of the geodesic dome high-voltage testing facility at PG&E’s Applied Technology Services Center (ATS) in San Ramon, Calif. PG&E tested the Nissan Leaf with Fermata Energy’s Vehicle-to-Everything (V2X) optimization platform and bidirectional charging stations at ATS before integrating the equipment set at the Redwood Coast Airport Microgrid.
The Redwood Coast Airport Microgrid (RCAM) in Northern California has integrated parked electric vehicles (EVs) as a buffer for excess solar generation. In a pilot project, Pacific Gas and Electric (PG&E), the Schatz Energy Research Center at Cal Poly Humboldt, Nissan and Fermata Energy demonstrated that bidirectional EV chargers can automatically respond to microgrid frequency changes, absorbing surplus generation and extending backup power during islanded operation without relying on external communication links.
Renewable-heavy microgrids face a challenge during islanding: midday solar production can exceed local load, forcing curtailment or risking instability precisely when resilience is most critical. By using EV batteries as fast, dispatchable storage and coordinating them through frequency-based controls, the project tests a low-communication method to smooth solar spikes, maintain power quality and potentially keep multi-customer microgrids online longer during earthquakes, wildfires or public safety power shutoffs.
RCAM pairs a 2.2 MW front-of-meter solar array and roughly 300 kW of behind-the-meter solar photovoltaic generation with a grid-forming battery energy storage system (2.3 MW / 8.9 MWh). Winter conditions and market dispatch can deplete battery reserves during extended outages. The new layer adds four Fermata FE-20 bidirectional chargers connected to two Nissan Leaf EVs, enabling the microgrid to shift into “absorb” mode when solar is abundant and “conserve” mode when supply is tight. PG&E states that if scaled, this approach could become a template for future multi-customer microgrids under its incentive program, especially in areas where solar overgeneration and wildfire-related outages are common.
The control scheme operates without network commands. When the microgrid islands and solar generation pushes the main battery’s state of charge too high, the Schatz Center’s grid-forming controller raises the system frequency slightly. The Fermata chargers detect this increase and begin charging the EVs, drawing excess power into the vehicle batteries. Conversely, if the battery becomes depleted, a frequency drop triggers the EVs to discharge back into the microgrid. This droop-style response uses frequency as a broadcast control channel, eliminating the need for cloud connectivity.
Such autonomy is valuable when communications fail. During the magnitude 6.4 earthquake that struck Humboldt County in December 2022, RCAM islanded and supplied power to roughly 20 customers, including the airport and a U.S. Coast Guard station, for nearly 15 hours. It came up about 30 minutes short of lasting until PG&E restored the circuit, Carter said. With bidirectional EVs in the system, says Schatz principal engineer David Carter, the microgrid would have made it across the finish line.
