Grid-scale battery safety progress amid US growth

As the US energy storage market experiences unprecedented growth, expanding from 1 GWh to 17 GWh since 2021 industry data suggests encouraging trends in safety performance.

According to the Electric Power Research Institute’s (EPRI) BESS [battery energy storage system] Failure Incident Database, while deployments have emerged globally, the failure rate per installed capacity has decreased significantly, indicating that lessons from earlier incidents are being successfully incorporated into designs and best practices.

“To be honest, from a manufacturer’s standpoint, passing or obtaining the certificates or passing those tests is actually the minimum requirement,” emphasized Dr. Zhehan Yi from CPS [Chint Power Systems] America during a recent webinar. “You’ve got to do much, much more for your product to improve safety.”

Current safety standards, particularly UL 9540 and UL 9540A, provide a foundation for battery system safety. However, experts point out significant limitations in these protocols. While UL 9540A tests thermal runaway propagation at the cell, module, and unit level, these laboratory conditions do not fully replicate real-world scenarios. Notably, the current standards don’t require full-scale fire testing – a gap that the upcoming CSA TS 800 standard aims to address in 2025.

EPRI’s  database , which tracks battery energy storage system failures globally, helps identify trends and inform future mitigation strategies. In collaboration with TWAICE [battery predictive analysis software] and PNNL [the Pacific Northwest National Laboratory], EPRI categorizes failure root causes across design, manufacturing, integration, operation, and physical location aspects. This systematic approach to understanding failures has contributed to the industry’s improved safety record.

Manufacturers are implementing multiple layers of safety features beyond minimum requirements. CPS America, for instance, has deployed 2 GWh of battery capacity globally without thermal events, by employing several key strategies. These include physically separating electrical components from battery cells and utilizing a string structure rather than centralized architecture for more granular monitoring and control.

Fire safety remains a primary concern for authorities having jurisdiction (AHJs) and first responders. Unlike conventional building fires, battery fires present unique challenges. Ryan Mayfield, of Mayfield Renewables, noted that firefighters often prefer visible fires to potential explosion risks from accumulated gases. “They will risk a lot to save a lot, they’ll risk a little to save a little,” Mayfield explained, highlighting how response strategies differ between battery systems in populated areas versus remote locations.

The industry is also learning from global practices. EPRI’s database encompasses events from various regions including China, Taiwan, Europe, South Korea, and the United States, although language barriers and limited local media coverage can affect data collection. In Asian markets, for example, certification processes include drop tests from heights of 13 feet to simulate real-world accidents – a requirement not currently mandated in US standards.

Long-term maintenance presents another critical safety consideration. As batteries age, their characteristics change, potentially affecting safety parameters. “Over time, battery characteristics can change. Internal resistance can change, heat dissipation characteristics can change as well,” Dr. Yi noted. This emphasizes the importance of comprehensive operations and maintenance (O&M) plans aligned with NFPA [National Fire Protection Association] 855 guidelines.

Remote monitoring capabilities are becoming increasingly sophisticated, allowing for early detection of potential issues. Modern battery management systems (BMS) can track multiple parameters in real-time, enabling preventive actions before problems escalate.

Looking ahead, the industry faces several key challenges:

1. Developing more realistic testing protocols that better reflect field conditions

2. Standardizing emergency response procedures across jurisdictions

3. Improving data collection and sharing of incident information

4. Balancing space efficiency with safety requirements

5. Maintaining system safety throughout multi-decade operational lifespans

As battery storage continues its rapid growth trajectory, with projections suggesting US capacity could exceed 100 GW by 2030, the industry’s focus on safety appears to be paying dividends. The declining failure rate documented by EPRI, combined with ongoing improvements in design, monitoring, and emergency response protocols, suggests that the industry is successfully managing safety risks while scaling deployment.

The consensus among experts is clear: While current safety standards provide a crucial foundation, the industry must continue pushing beyond minimum requirements, learning from global best practices, and maintaining vigilance throughout system lifecycles. EPRI’s database serves as a valuable resource for this continuous improvement process, helping ensure that grid-scale battery storage can fulfill its essential role in the clean energy transition while maintaining the highest safety standards.

Tim Montague leads the Clean Power Consulting Group and is host of the Clean Power Hour podcast. He is a solar project developer, cleantech executive coach and consultant, mastermind group leader, entrepreneur, and technology enthusiast.

From pv magazine USA.