Key Findings
The annual failure rate of lithium-ion BESS declined by 98% globally from 2018 to 2025. In 2025, 24 incidents were recorded across 634 GWh of cumulative deployed capacity, compared to 26 incidents across 343 GWh in 2024, representing a 50% year-over-year decrease in the failure rate. Regional reductions were led by China at 99%, followed by the U.S. (97%), South Korea (91%), and Europe (85%). Oceania recorded no failures in 2025.
Technical Details
The EPRI database tracks large-scale thermal events caused by internal faults, such as arc flashes, fires, or explosions, excluding external factors like wildfires. Key technical observations include:
- Installation Environment: Indoor systems suffered disproportionately higher damage; the median proportion of damaged capacity was 100% for indoor systems versus 6% for outdoor systems.
- System Age: Each additional year of operation was associated with a 31% reduction in failure rates, while each successive installation year saw a 44% reduction.
- Chemistry: While LFP and NMC accounted for 96% of deployments by 2022, EPRI found insufficient evidence to establish battery chemistry as an independent risk factor.
- Comparative Risk: The average annual container failure rate (0.04% to 0.14%) is comparable to large oil-filled transformers.
Background and Context
Of the 150 total incidents recorded, 33 (22%) were not publicly reported. South Korea had the highest total incidents (55), followed by the U.S. (36), China (25), Europe (20), and Oceania (4). Regarding public safety, 18 incidents involved explosions, resulting in 24 injuries and four fatalities. No acute injuries among the general public were reported, and no fires were found to have spread beyond utility-scale facilities.
Significance and Outlook
EPRI recommends defensive response strategies focusing on thermal monitoring, explosion prevention, and the potential retirement of older systems that fail to meet current safety standards. The findings underscore the importance of evolving regulations, such as the technical standards recently proposed by India’s Central Electricity Authority.
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