Clamp failure and coolant leak found during Moss Landing battery restart testing
2025Published 16 Sept 2026Responsible editor: Chief Editor
- Where
- Elkhorn Battery Energy Storage System, Moss Landing, California
- Operator
- PG&E
- Manufacturer
- Tesla
- What
- Clamp failure and coolant leak in one Megapack
- Injuries
- None reported
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Companies named in the reporting of this entry (being named is not a finding of fault): Tesla, Vistra Energy
What happened
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.
Contributing factors
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.
Lessons learned
- A clamp failure in a Tesla Megapack led to a coolant leak, so operators should inspect clamps on identical units before full reactivation after shutdown.
- Phased restart testing after an extended shutdown can reveal latent mechanical faults before they cause fire or outage.
- A single Megapack clamp failure warrants fleet-wide checks on the thermal management system to prevent repeats.
More lessons on maintenance, inspection and ageing assets, outages, backup supply and restoration, investigation and fleet-wide checks, from every incident on the register.
Not yet known
- Underlying cause of the clamp failure
- Turbine model and age
- Cost of the repairs
- Downtime duration details
This entry is updated when these are reported. Get an alert for the next one like it.
Source
Site page: Elkhorn Battery Energy Storage System (status, dates and other incidents)
Other entries that name Moss Landing
- New fire smoulders at Vistra Moss Landing battery site during cleanup
- Major fire at Moss Landing Energy Storage Facility, California, multi-day incident
- Battery storage fire reignites at Vistra's Moss Landing facility
- Megapack fire at PG&E Elkhorn Battery, Moss Landing, California
- Water based suppression system leak causes battery shorting at Moss Landing Phase II
Published 2026-09-16. Written from public reporting. Descriptive, not investigative. See the data accuracy disclaimer.
