Shanghai – September 07, 2026 -- APsystems' APstorage 261L liquid-cooled commercial and industrial energy storage system has passed UL 9540A fire propagation testing, with thermal runaway fully contained within a single enclosure under witness from TÜV Rheinland.
Tests under extreme conditions show zero fire spread
The APstorage 261L cabinet was tested at 100% state of charge with its fire suppression system deliberately disabled. No short circuit, fire spread, or explosion occurred, and the cabinet maintained structural integrity throughout the test.
Heat flux readings measure far below UL 9540A threshold
Heat flux density near the tested cabinet registered 0 kW/m2, well under the UL 9540A threshold of 1.3 kW/m2, eliminating ignition risk to adjacent equipment from thermal radiation. Maximum module surface temperature reached 83.9°C on both the tested and neighboring modules, indicating effective containment between modules. The maximum temperature on the adjacent wall was 30.6°C, only 3.1°C above ambient, confirming minimal thermal impact on surrounding space.
Liquid-cooled single-cluster design limits cell temperature variance
The APstorage 261L uses a single-cluster architecture with liquid cooling, keeping cell temperature variance below 3°C to extend battery lifespan while improving operational safety. Its safety architecture combines a four-tier fire protection system, active ventilation, and passive pressure-relief mechanisms across cell, module, and enclosure levels.
Compact 1.3-square-meter footprint targets European C&I deployment
The system occupies 1.3 square meters and features plug-and-play connectors for simplified installation and commissioning. Its modular architecture allows capacity expansion through parallel connection of multiple cabinets, targeting industrial sites, commercial buildings, and projects combining solar generation, storage, and charging infrastructure. APsystems supports the product through its European network and a dedicated C&I energy storage warehouse in the Netherlands, providing local market access, training, and on-site technical support.