As residential energy storage systems grow in adoption, safety has become a critical concern for households worldwide. Incidents involving energy storage can lead to severe outcomes, and rising reports of accidents have amplified public attention. In a move to strengthen industry trust and raise safety performance, Sungrow has expanded its rigorous testing protocols from utility-scale storage to residential solutions. The company’s SBH Series for home use has achieved a landmark result—passing the world’s first UL 9540B large-scale fire test administered by UL Solutions. This success underscores Sungrow’s leadership in managing thermal runaway and preventing fire propagation, establishing a new international reference for residential ESS safety.

UL 9540B, developed specifically for residential energy storage units of 20kWh or less, is recognized as one of the industry’s most demanding safety benchmarks. The test induces forced thermal runaway in fully charged systems, replicating severe fire conditions such as flammable gas accumulation, venting, and external ignition. It assesses the system’s capability to avoid fire spread, explosions, and secondary hazards, requiring excellence in insulation, gas control, thermal runaway containment, and structural design.

Under these extreme conditions, Sungrow’s SBH Residential ESS endured a challenging 24-hour evaluation. Despite tightly arranged battery modules, disabled fire suppression systems, continuous ignition sources, and no external aid, the system exhibited robust inherent safety and met all test criteria.

Fire Spread Contained: Isolating the Hazard

The SBH system displayed superior fire confinement during testing, supported by cell-level fire-resistant barriers, bottom heat dissipation, and multi-vent pressure relief. When one unit entered thermal runaway, flames were limited to the pressure relief zone. Adjacent units maintained internal surface temperatures of only 21°C—far below the 154°C venting point—while eave temperatures reached just 35°C, well under the 150°C safety threshold.

Self-Extinguishing in One Hour: Halting Fire at its Origin

Through structural designs that promote heat dissipation and module-level thermal isolation, the SBH ESS localized the thermal runaway to the bottom module. Without any firefighting intervention, open flames died out within one hour. Attempts to reignite the system over the following 24 hours were unsuccessful, validating its reliable safety performance.

No Explosions or Projectiles: Ensuring Maximum Protection

With active fire suppression turned off for the duration, the SBH system experienced no explosions, projectiles, or uncontrolled combustion. The cabinet structure remained fully intact, demonstrating high resistance to fire, explosion, and structural failure.

Having previously passed the UL 9540A Thermal Runaway Fire Propagation Test, Sungrow’s SBH Residential ESS now adds the UL 9540B large-scale fire test to its credentials. This back-to-back achievement verifies the system’s end-to-end safety—from cell-level runaway control to full-system fire containment. Homeowners can now trust in the SBH system’s ability to perform safely under real-world fire conditions.

As a worldwide leader in energy storage, Sungrow remains dedicated to advancing and enforcing the highest safety standards in the sector. Through ongoing innovation, Sungrow aims to deliver safety-focused technologies that allow households to use clean energy with confidence and peace of mind.