Battery overheating forces shutdown of Moss Landing Phase I storage facility
Sept 2021Published 10 Sept 2026Responsible editor: Chief Editor
- Where
- Moss Landing Energy Storage Facility in California
- Operator
- Vistra Energy
- What
- Overheating in limited battery modules, no fire
- Response
- Fire crews responded, targeted sprinklers activated
- Outcome
- Phase I taken offline pending investigation
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Companies named in the reporting of this entry (being named is not a finding of fault): Fluence, LG Energy Solution, Vistra Energy
What happened
On 4 September 2021, the Moss Landing Energy Storage Facility in California, operated by Vistra Energy, experienced an overheating issue affecting a limited number of battery modules in its Phase I 300 MW/1200 MWh system. Local fire crews responded to a reported structure fire around 8pm but found no fire, instead discovering scorched battery racks and melted wires. Vistra Energy said its risk mitigation and safety systems detected modules operating above normal temperature and activated targeted sprinkler systems aimed at the affected modules.
The company stated the event was controlled and contained without external assistance, though fire crews remained on site overnight. The entire Phase I facility was taken offline pending an investigation into the root cause, conducted with engineering contractor Fluence and battery manufacturer LG Energy Solution. The adjacent Phase II 100 MW system, in a separate building, was unaffected and remained operational.
Contributing factors
Vistra Energy stated it had not determined a root cause at the time of reporting and cautioned against assuming the batteries themselves caused the incident. The article notes LG Energy Solution had separately announced a battery cell replacement programme in May 2021 for cells made between April 2017 and September 2018 due to electrode production issues, though it is not stated whether these cells were used at Moss Landing.
Lessons learned
- Targeted sprinklers can contain battery module overheating before it becomes open fire.
- Separate buildings for each phase limit an incident to one phase only.
- Fire crews need prior briefing on battery layouts, as a structure fire call may mean no flame.
More lessons on fire suppression and firefighting, from every incident on the register.
Not yet known
- Root cause of the overheating
- Battery cell model and production date
- Length of Phase I shutdown
- Cost of repairs
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
- Clamp failure and coolant leak found during Moss Landing battery restart testing
- Battery storage fire reignites at Vistra's Moss Landing facility
- Megapack fire at PG&E Elkhorn Battery, Moss Landing, California
Published 2026-09-10. Written from public reporting. Descriptive, not investigative. See the data accuracy disclaimer.
