Battery overheating forces shutdown of Moss Landing Phase I storage facility

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.

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.

1. Automated thermal detection and targeted suppression systems can contain overheating events before they escalate to open fire, limiting damage and risk to responders.
2. Fire services should be briefed on battery storage site layouts and detection systems in advance, since a reported structure fire may in fact be a contained thermal event with no visible flame.
3. Operators should maintain transparent public communication distinguishing confirmed facts from ongoing investigation findings, avoiding premature attribution of cause.
4. Segregating battery system phases into separate buildings can limit the impact of an incident to a single phase, keeping unaffected capacity operational.

pv-magazine-usa.com/2021/09/07/moss-landing-energy-storage-facility-knocked-...