California utility Pacific Gas and Electric (PG&E) has pushed back recommissioning of the Elkhorn battery energy storage system (BESS) by approximately one year, to 30 June 2026.
This announcement was made via a statement, obtained by Energy-Storage.news, sent by PG&E.
The 182.5MW/730MWh Elkhorn BESS was automatically shut down when the Moss Landing Energy Storage Facility, located on the opposite side of the legacy Moss Landing gas plant site, caught fire in January.
In May, PG&E announced its intent to return the BESS to service by 1 June 2025.
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Elkhorn, first commissioned in April 2022, uses Tesla Megapacks and is the only BESS owned by PG&E. The company currently contracts all other BESS projects, including the Moss Landing Energy Storage Facility, which is owned by power producer Vistra Energy.
PG&E’s statement reads, “On 1 June, 2025, PG&E began methodically returning the Elkhorn system’s batteries to service as a part of a planned return to service. PG&E took a conservative approach to testing and restarting the system to identify any operational issues and ensure continued safe operations.”
“In the process of testing, a clamp failure and subsequent coolant leak were identified in one of the 256 Megapacks onsite. There were no injuries, power outages, smoke, or fire associated with the clamp failure and coolant leak.”
Tesla, which supplied and maintains the BESS, evaluated the clamp that failed, and PG&E says the company is developing an inspection and repair plan. Based on the information available to PG&E, it estimates 30 June 2026 as the return to service date for the BESS.
The statement continues, “With the exception of connecting to maintain at or near minimum state of charge, the Elkhorn system will remain electrically disconnected from the grid in a safe, idle state until the necessary repairs are completed.”
“PG&E is in contact with local stakeholders about the repairs that need to be made and the timing of our deferred restart. We are committed to keeping all appropriate stakeholders and the community informed of work progress or updated timelines.”
In September 2022, a fire happened at Elkhorn that was confined to a single battery pack.
Tesla and PG&E appear to have resolved that situation appropriately. Energy Safety Response Group (ESRG) performed an assessment of the incident, and Tesla quickly resolved the issue of improper installation of deflagration vent shield panels.
The two companies also regularly monitored air and water quality throughout the clean-up of Elkhorn.
