EPRI Finds Battery Storage Failure Rates Fell 98% Since 2018, But 22% of Its Incidents Are Not Public

The Electric Power Research Institute (EPRI) says the global failure rate of lithium-ion battery energy storage systems (BESS) fell 98% per deployed GWh from 2018 to 2025. The finding is in an October 2026 EPRI white paper, Risk Factors and Failure Statistics of Lithium-Ion BESS. In 2025, there were 24 incidents and 634 GWh deployed globally, EPRI says. That is a 50% reduction in failure rate from 2024, when there were 26 incidents in a global fleet of 343 GWh.

In the United States, EPRI counts 36 failures from 2018 through 2025, against 149 GWh of cumulative deployment. EPRI Table 2 lists that as a 97% failure rate reduction for the U.S. EPRI defines a failure incident as a large-scale thermal event involving arc-flash, fire, or explosion of a BESS unit, pv magazine USA reports. It counts only failures with a cause internal to the BESS.

What the Data Shows

EPRI puts annual BESS failure rates at 0.04% to 0.14%. It calls that comparable to the 0.1% annual failure rate for oil-filled electrical transformers, Utility Dive reports. For 93% of incidents in the database, no injuries or fatalities were reported. EPRI found no report of fire spreading beyond a utility-scale BESS facility.

Indoor BESS facilities are overrepresented in failure incidents and sustain more damage on average. EPRI recommends fire walls or other barriers to segment large indoor facilities. The largest U.S. case was Moss Landing in California. In January 2025, thermal runaway spread through the indoor facility and destroyed most of the 300 MW battery array, Utility Dive reports. BESS facilities commissioned before 2021 account for just 3% of global energy storage capacity, according to the report as Utility Dive describes it.

The Gap

The database is not complete. It holds 33 non-public incidents, which account for 22% of the total. EPRI says “limited transparency and data gaps remain a major challenge to a complete database.” EPRI also could not separate cell chemistry from design maturity as a risk factor. The fleet shifted from NMC to LFP chemistry in the same years that failure rates fell.

Counts also differ on the 2019 explosion in Surprise, Arizona. pv magazine USA reports that it left eight first responders hospitalized. EPRI counts four injuries. Four firefighters were critically injured, and four more were observed overnight for possible hydrogen cyanide exposure. EPRI says those four do not count as reportable injuries under OSHA definitions. Since that incident, EPRI reports no injuries or fatalities in the U.S. related to BESS failures.

Why It Matters

The rate counts every failure equally, so a 200 kWh commercial system counts the same as a failure at a site of several hundred MWh. Local permits are where these numbers land. EPRI senior technical leader Lakshmi Srinivasan told Utility Dive that limits in the NFPA 855 standard lead most developers to apply for exemptions. Since January, New York’s fire code lets local authorities make developers pay for independent technical reviews of those exemption applications. Srinivasan also said owners of older facilities should run thorough risk assessments and take corrective action if warranted.

Sources

• EPRI, Risk Factors and Failure Statistics of Lithium-Ion BESS, white paper (October 2026)
• Utility Dive, Battery system failures fell 98% in 7 years, but older systems need special care: report (October 13, 2026)
• pv magazine USA, Battery energy storage failures are down 98% since 2018 and continue to decline (October 14, 2026)