Clamp failure and coolant leak found during Moss Landing battery restart testing

PG&E began returning its Elkhorn Battery Energy Storage System at Moss Landing, California to service on 1 June 2025, following an automatic shutdown on 16 January 2025 when the system's infrared fire detection picked up flames from a fire at the neighbouring Vistra Energy battery facility. During testing, PG&E identified a clamp failure and a subsequent coolant leak in one of the 256 Tesla Megapacks on site. PG&E said there were no injuries, power outages, smoke or fire associated with the clamp failure and coolant leak. Tesla, which maintains the Elkhorn system for PG&E, has evaluated the failed clamp and is developing an inspection and repair plan. PG&E's best estimate for a return to service is now 30 June 2026. The system will remain electrically disconnected from the grid in a safe, idle state, apart from connecting to maintain at or near minimum state of charge, until repairs are completed.

A clamp failure in one Megapack led to a coolant leak during the planned, staged restart and testing process that PG&E began after the extended shutdown caused by the neighbouring facility fire. The underlying cause of the clamp failure is not reported.

1. Phased, conservative restart testing after an extended shutdown can surface latent mechanical issues before they escalate into more serious failures.
2. A single component failure affecting a coolant or thermal management circuit warrants inspection across the wider fleet of identical units before full reactivation.
3. Operators should keep local stakeholders informed when safety-driven repairs extend return to service timelines.

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