Large-scale fire test results
SK On met relevant North American safety assessment criteria in a large-scale fire test of its energy storage system (ESS) batteries. The test found no thermal runaway in battery cells inside equipment adjacent to the container where the fire occurred.
SK On said on October 28 that its ESS had completed UL 9540A large-scale fire testing (LSFT) and that it had obtained a test report.
UL 9540A is a standard for assessing how heat and fire spread to surrounding areas when battery thermal runaway occurs. Large-scale fire testing simulates an ESS fire to examine factors including whether it spreads to adjacent equipment. Detailed assessment requirements were tightened in March 2026.
SK On explained that it designed the system to dissipate heat generated by the batteries over an extended period. In this test, no thermal runaway occurred in battery cells inside the adjacent container, and temperatures inside the container also met the assessment criteria.
ESS contracts and production
In its ESS business, SK On signed a 1 GWh supply contract with US renewable energy company Flatiron in September 2025. In August 2026, it signed a lithium iron phosphate (LFP) battery supply contract with US ESS company NeoVolta Power.
In South Korea, it secured 284 MW in the second central contract market tender in February 2026. The total tender volume at the time was 565 MW. At its Seosan plant in South Chungcheong Province, it is converting 3 GWh of its total production capacity of 7 GWh into production lines for ESS LFP batteries.
Original Korean article: datasom.co.kr
English brief by Korea Wind Intelligence, koreawindintel.com
