Lithium-ion battery explosion reported to have led to a prolonged thermal event at a US site

What happened

At about 11.40am on 22 September 2026, local authorities reported a fire at a United States installation with a battery energy storage system next to a solar panel field. They believed a lithium-ion battery explosion had started the fire, which first involved one of two storage systems. Crews brought that unit under control and cooled the enclosure with water. Heat then damaged the neighbouring system, and packs there were reported to be entering thermal runaway.

Cooling and monitoring continued for several days, with air-quality checks around the perimeter. The associated water-treatment facility and its water supply were not affected. On 25 September, specialists and firefighters began dismantling the damaged equipment, disconnecting packs, reducing voltages, and separating cells on a lay-down area before packaging and disposal. Damaged material needed a cooling period, specialist packaging and neutralisation before it could be moved. Two undamaged storage units were taken offline and de-energised.

Fire overwatch and air monitoring continued during removal, and evacuation orders and warnings were lifted once the immediate hazard had been reduced. The cause and origin had not been established, and the investigation was still open.

Contributing factors

Authorities believed a lithium-ion battery explosion started the fire, but the cause and origin had not been established. Heat from the first fire was reported to have damaged an adjacent storage system, after which packs there entered thermal runaway.

Lessons learned

1. Where heat can pass from one storage unit to another, plan for cooling and monitoring that may last several days, not only the first attack.
2. Dismantling after thermal runaway should include isolation, voltage reduction and physical separation of cells before handling and transport.
3. Damaged cells may need a cooling period, specialist packaging and neutralisation, with fire overwatch and air monitoring until the material has left the site.

Source

hazardexonthenet.net