Battery fire at Valley Center Energy Storage System, California
Sept 2023Published 1 May 2026Responsible editor: Chief Editor
- Where
- Valley Center Energy Storage System, Valley Center, San Diego County, California
- Operator
- Terra-Gen
- What
- Fire in about 100 decommissioned lithium-ion battery packs
- Injuries
- None reported
- Cause
- Under investigation
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Companies named in the reporting of this entry (being named is not a finding of fault): Terra-Gen
What happened
In September 2023, a fire occurred in the late afternoon at the Valley Center Energy Storage System in Valley Center, San Diego County, California, operated by Terra-Gen. Fire and sheriff's departments were dispatched, roads in the area were closed, an evacuation order was issued for an area within about a quarter of a mile of the site, and shelter in place advice was given for an area of about half a mile.
Reporting indicated that the fire involved approximately 100 lithium-ion battery packs which, according to later statements from Terra-Gen, had been decommissioned, palletised and were awaiting collection for recycling. Those packs had been taken out of service after a sensor system fault activated the water based protection system. Public safety measures were lifted about four hours after the fire was reported, and Terra-Gen stated that the incident was concluded by the following morning. No injuries were reported.
Contributing factors
Sources reported that the cause of the fire was under investigation at the time of publication. Statements from Terra-Gen described an earlier sensor system fault that activated the water based protection system, after which the affected battery packs were decommissioned, palletised and stored on site pending removal for recycling. Terra-Gen also stated that the decommissioned units were segregated from operating equipment and that the site containment arrangements limited the extent of the fire. No mechanism linking the earlier fault or water exposure to the fire had been publicly confirmed at the time of reporting.
Lessons learned
- Decommissioned lithium-ion packs can still catch fire, so operators must keep them under the same monitoring and containment rules as live units.
- Water from a protection system may damage packs and raise later fire risk, so specialist advice is needed before storage or transport.
- Segregation of decommissioned packs limited fire spread, so operators should confirm separation distances in site records and emergency plans.
More lessons on detection and monitoring, electrical protection and isolation, spacing, layout and fire spread, from every incident on the register.
Not yet known
- Exact cause of the fire
- Battery pack model and age
- Cost of damage and downtime
This entry is updated when these are reported. Get an alert for the next one like it.
Published 2026-05-01. Written from public reporting. Descriptive, not investigative. See the data accuracy disclaimer.
