A New Benchmark in Residential Energy Storage Safety: Sungrow Passes the World’s First UL 9540B Fire Test

As residential energy storage systems become an integral part of modern homes, safety has moved from a technical requirement to a decisive purchasing factor. Homeowners expect energy storage not only to deliver performance and savings, but also to operate with absolute reliability—even under extreme and unlikely fault conditions.

In this context, Sungrow has opened a new chapter in residential ESS safety. Its SBH Series residential energy storage system has successfully passed the world’s first UL 9540B large-scale residential fire test, conducted by UL Solutions. This milestone sets a new global reference point for how residential battery systems should manage thermal runaway, fire containment, and secondary risk prevention.

Why UL 9540B Matters for Homeowners

UL 9540B is widely recognized as the most demanding fire safety test ever developed for residential energy storage systems in the ≤20 kWh category. Unlike certification checks based on theoretical models or component-level tests, UL 9540B simulates worst-case real-world fire scenarios.

During the test, fully charged battery systems are deliberately forced into thermal runaway while exposed to:

• flammable gas accumulation,

• continuous ignition sources,

• disabled active fire suppression,

• closely spaced installations typical of residential environments,

• and zero external firefighting intervention.

The goal is clear: to evaluate whether a residential ESS can contain fire, prevent explosions, stop fire spread, and protect surrounding property and occupants under extreme conditions.

SBH Series: Proven Safety Under the Harshest Conditions

Against these uncompromising requirements, Sungrow’s SBH Residential ESS completed a continuous 24-hour UL 9540B fire test with outstanding results.

Even with active fire suppression intentionally disabled, the system relied solely on its inherent structural and thermal safety design—and succeeded.

Fire Containment Where It Matters Most

During induced thermal runaway, flames were strictly confined to the pressure relief zone, preventing lateral or vertical fire spread. Adjacent battery units remained effectively isolated, with internal surface temperatures measuring only 21°C, far below critical thresholds.

Temperature readings near surrounding structures, such as eaves, peaked at just 35°C, staying well within safety margins. This confirms that the SBH system is engineered not merely to resist fire, but to lock in risk at the source, protecting both the installation environment and nearby living spaces.

Self-Extinguishing by Design

One of the most critical outcomes of the test was the system’s ability to self-extinguish without intervention. Thanks to advanced heat dissipation pathways, fire-resistant insulation, and optimized thermal isolation between modules, thermal runaway was confined to a single module.

Within one hour, open flames extinguished naturally. Over the following 24 hours, repeated ignition attempts failed to reignite the system—demonstrating a level of passive fire control rarely seen in residential ESS designs.

No Explosions, No Projectiles, No Structural Failure

Perhaps most importantly for residential safety, the SBH ESS showed zero explosion risk throughout testing. Despite internal gas release and continuous ignition exposure, the cabinet remained structurally intact. There were no projectile hazards, no violent combustion events, and no enclosure failure.

This performance validates Sungrow’s comprehensive approach to pressure management, venting design, and cabinet integrity, ensuring maximum protection even under extreme internal stress.

From Certification to Confidence

Having already passed the UL 9540A thermal runaway propagation test, the SBH Series now adds UL 9540B large-scale residential fire validation—confirming protection from the cell level all the way to the full system.

For homeowners, installers, and insurers, this means something very concrete:
confidence that the system is designed for real-life emergencies, not just compliance checklists.

Setting the Future Standard for Residential ESS Safety

As residential solar-plus-storage adoption accelerates globally, safety expectations will continue to rise. Sungrow’s achievement does more than validate one product—it raises the bar for the entire industry.

With the SBH Residential ESS, Sungrow demonstrates that high energy density, performance, and intelligent control can coexist with industry-leading fire safety. It is a clear signal that the future of residential energy storage must be built on proactive risk prevention, not reactive mitigation.