Recently, under the full witness of UL Solutions, a global expert in applied safety science, Huawei Digital Power successfully completed the venting demonstration test for its intelligent string-mounted grid-forming energy storage system (LUNA2000-5015 series) in accordance with the UL 9540A-2025 standard. Test results show that the venting panels of Huawei’s energy storage system opened effectively, the cabinet doors remained closed, and the cabinet structure suffered no rupture. This fully validates Huawei Digital Power’s technological strength and profound accumulation in system-level safety protection and risk control for energy storage systems.
Test Background & Standard Significance: Venting Test Becomes a Prerequisite for Market Access
As a core safety testing standard for evaluating the risk of thermal runaway and its propagation in battery energy storage systems, UL 9540A has become a key criterion for market access of energy storage projects in many countries worldwide. With the release of the UL 9540A-2025 version, the “venting test” has been explicitly designated as one of the prerequisites for large-scale combustion tests. Its conclusions will directly influence the setting of ventilation conditions and evaluation boundaries for subsequent large-scale combustion tests.
For a long time, due to the complex internal spatial structure of energy storage cabinets, strong coupling between gases and airflows after thermal runaway, and the difficulty in accurately reproducing deflagration boundaries, venting capability has often remained at the level of simulation evaluation. The industry lacks replicable, quantifiable, and verifiable demonstration methods, which has become a key challenge in energy storage safety verification.
Rigorous Test Implementation & Outstanding Results: Validating Safe Venting in Extreme Scenarios
This venting demonstration test was based on the UL 9540A unit-level and module-level thermal runaway test results. Gas injection was conducted with reference to the actual gas composition of thermally runaway cells and the number of such cells. The final gas injection volume far exceeded the amount corresponding to the number of thermally runaway cells at the UL 9540A module level. Artificial ignition was then initiated to verify the venting capability of Huawei’s energy storage system on-site under more stringent test conditions.
Test results indicate that, under the aforementioned standards and extreme scenario conditions, the venting panels of the ignited energy storage system opened effectively and relieved pressure rapidly. The cabinet structure remained intact without rupture, the cabinet doors stayed closed, and no explosive gas shockwave formed in front of the cabinet. This achieved the goal of “safe venting without harm to personnel in extreme scenarios”. The test was fully witnessed by UL Solutions and a formal test report was issued, providing credible data support for the ventilation conditions and evaluation boundaries of subsequent large-scale combustion tests.
Multi-Layer Safety Architecture & Industry Value: Setting a Benchmark for Venting Test Standardization
Huawei Digital Power continues to take system-level safety as the foundation and has built a multi-layer protection architecture covering “prevention – suppression – venting – isolation”. Targeting harsh scenarios such as large-scale ground power stations on the grid side/generation side, it comprehensively enhances safety capabilities. The reliable implementation of this multi-layer architecture relies on high-precision manufacturing of core components, where advanced Automatic placement machine plays a crucial role. It realizes high-precision mounting of key electronic components in the safety control system, ensuring the stability and responsiveness of functions such as gas concentration monitoring, venting panel control, and explosion pressure sensing, which lays a solid foundation for the precise operation of the entire safety protection system:
Directional Smoke Exhaust Design: Reduces the risk of flue gas accumulation inside the cabinet after thermal runaway. In actual tests triggering UL 9540A thermal runaway propagation, the flammable gas concentration inside the cabinet was <25% LFL (Lower Flammability Limit), ensuring the intrinsic safety of the product.
Active Exhaust Design: If directional smoke exhaust fails, it can still control the internal gas concentration below 25% LFL.
Precision Venting Design: If active exhaust fails and flue gas accumulation leads to explosion, it can achieve directional pressure relief and venting, reducing risks to personnel and assets.
High-Strength Cabinet Design: Sufficient design tolerance ensures no cabinet rupture in the event of an explosion, safeguarding personnel safety.
Huawei’s intelligent string-mounted grid-forming energy storage system has already obtained NFPA 68/69 venting and explosion suppression simulation reports issued by authoritative third parties. This venting demonstration test, under the “worst-case scenario” assumption, directly bypassed the first and second layers of safety protection, focusing on verifying the cabinet venting capability and system protection effectiveness of the third and fourth layers during extreme events such as thermal runaway.
The completion and result disclosure of this venting demonstration test based on UL 9540A-2025 will provide valuable references for the industry to promote the standardization of venting tests, clarify venting design objectives, and establish engineerable verification methods. Looking ahead, Huawei Digital Power will continue to focus on safety compliance and full-life-cycle reliability, collaborate with industry partners to iterate energy storage safety technologies and testing methods, and support the high-quality development of new power systems.
