APsystems Achieves Key Safety Milestone with APstorage 261L UL 9540A Test Success

SHANGHAI, Sept. 3, 2026 /PRNewswire/ -- APsystems has reached a major safety milestone for its commercial and industrial (C&I) energy storage portfolio. Under the witness of TÜV Rheinland, the APstorage 261L liquid-cooled storage solution successfully passed the rigorous UL 9540A fire propagation test, demonstrating exceptional fire safety performance. During testing, thermal runaway was fully contained within a single cabinet, with no propagation to adjacent units, exceeding industry-standard safety requirements.

UL 9540A is widely recognized as one of the most stringent safety standards for energy storage systems worldwide. The test evaluates thermal runaway behavior at the cell, module, unit, and installation levels, measuring heat release, smoke generation, temperature rise, and system response to verify resistance to fire and explosion hazards.

Exceeding Industry Standards

The APstorage 261L storage cabinet was subjected to testing under extreme conditions, operating at 100% state of charge (SOC) with its fire suppression system intentionally disabled. Even under these demanding circumstances, no short circuit, fire spread, or explosion occurred, and the cabinet maintained its structural integrity throughout the test.

Key Test Results

• Heat Flux: 0 kW/m² measured near the affected cabinet, significantly below the UL 9540A threshold of 1.3 kW/m², eliminating the risk of adjacent equipment ignition through thermal radiation.
• Maximum Module Surface Temperature: 83.9°C on both the affected and neighboring modules, demonstrating that thermal propagation between modules was effectively prevented.
• Maximum Adjacent Wall Temperature: 30.6°C, only 3.1°C above ambient temperature, confirming an almost negligible thermal impact on the surrounding environment.

At every stage of the test hierarchy, from cell to module to cabinet level, thermal runaway remained fully confined within a single enclosure, successfully preventing any propagation to neighboring cabinets.

Safety by Design

Safety is embedded into every aspect of the APstorage 261L's design. The system features a single-cluster liquid-cooling architecture, maintaining cell temperature variation below 3°C to improve battery longevity while enhancing operational safety.

A comprehensive safety architecture combines:

• 4‑level fire‑protection system
• Active ventilation
• Passive pressure relief mechanisms

Together, these elements create a robust, multi-layered safety framework that protects the system from the cell level through to the complete installation.

Compact, Flexible, and Optimized for European C&I Projects

Beyond its outstanding safety performance, the APstorage 261L has been engineered to support fast and flexible deployment across European commercial and industrial applications.

With a footprint of just 1.3 m², the system features plug-and-play connections for simplified installation and commissioning. Its modular architecture enables seamless parallel expansion across multiple cabinets, making it an ideal solution for industrial facilities, commercial buildings, and solar-storage-charging applications.

Supported by APsystems' extensive European network and a dedicated C&I energy storage warehouse in the Netherlands, APstorage provides local product availability, professional training, and reliable on-site technical support.

As APsystems continues to expand its portfolio of end-to-end energy storage solutions, APstorage remains committed to delivering ever-higher levels of safety, performance, and reliability.

For more information, visit:

https://emea.apsystems.com/apstorage-ci/