Becoming the first modular DC-coupled C&I ESS to achieve triple-level certification
Sungrow’s commercial and industrial (C&I) energy storage system, PowerKeeper, has successfully completed cell, module, and unit-level thermal runaway tests under UL 9540A, becoming the first modular DC-coupled C&I ESS to achieve triple-level certification
Witnessed by TÜV Rheinland, the testing confirms PowerKeeper’s ability to prevent thermal runaway propagation across multiple system layers, setting a new benchmark for safety in commercial and industrial energy storage.
A New Approach
In commercial and industrial environments, energy storage systems are typically installed in high-density spaces where people, equipment, and valuable assets coexist, which means safety requirements extend beyond basic compliance. The fundamental challenge in battery safety is preventing thermal runaway propagation before risks can escalate.
UL 9540A is recognised as the global benchmark for evaluating thermal runaway risks in energy storage systems. However, current industry practice often focuses on single-tier testing, either by validating cell-level parameters alone or demonstrating compliance at the module or system level. This testing method cannot fully demonstrate whether every safety barrier within a system can contain potential risks.
PowerKeeper has been designed to address this issue through a comprehensive triple-layer safety validation approach.
Safety Evidence Chain
Through its cell-module-unit triple UL 9540A certification, PowerKeeper establishes a safety validation chain across three system layers:
- Cell-level testing captures critical thermal runaway parameters.
- Module-level testing verifies that thermal runaway can be contained within the battery module.
- Unit-level testing demonstrates effective thermal isolation between adjacent cabinets and surrounding structures.
These layers of validation help to ensure that PowerKeeper can maintain system integrity under all conditions.
Validated Under Installation Constraints
Energy storage systems are often placed close to walls or adjacent to other cabinets because commercial and industrial sites have limited installation space. PowerKeeper enables space-efficient installation and adapts to diverse and complex site conditions. The test simulates real-world installation scenarios, with clearances set at 25mm from walls and 450mm between cabinets.
- Unit-level test: The triggered battery cell reached a peak temperature of 595.2°C and demonstrated exceptional containment capabilities.
- No Impact on Adjacent Cabinets: With a unit spacing of 450mm, the neighbouring unit recorded a maximum surface temperature of 13.7°C, far below the 141.3°C threshold defined by UL 9540A.
- Safe Operation with Minimal Wall Clearance: With a wall clearance of 25mm, the wall surface temperature rose to 29°C, below the 97°C limit specified by the standard.
- Module-Level: Precision Mitigation: Thermal runaway was intentionally triggered in three cells, resulting in no combustion, no explosion, and no external debris or splashing. This confirms that potential hazards are contained within the PACK, even under triggered conditions.
- Cell-Level: Control at the Source: The cell’s explosion-proof valve immediately activated to release pressure and prevent any combustion or explosion, while capturing precise thermal runaway trigger temperature of 216.3°C during cell-level testing.
Passive Protection and Intelligent Safety
While UL 9540A certification validates PowerKeeper’s passive safety performance under extreme conditions, Sungrow also integrated advanced safety mechanisms to protect against everyday operational conditions.
Aligned with the PowerKeeper “7 Ups” safety concept, the system features:
- 5D alerts (current, voltage, smoke, full-stack temperature monitoring, and water immersion detection)
- Triple-guard protection across cell, pack, and plant levels
These features establish a comprehensive cell-to-plant safety architecture, enabling early risk detection, precise warning, and rapid intervention during daily operation.
