Huawei’s grid forming BESS delays fire ignition for seven hours in extreme test

Huawei Digital Power’s Smart String & Grid Forming Energy Storage System (ESS) has successfully passed an extreme ignition test in the presence of customers and Norway-headquartered independent assurance and risk management provider DNV.

Exceeding the requirements of the international standard UL 9540A test method and conducted under real-world scenarios, Huawei subjected a significant number of cells to thermal runaway to verify the safety protection capabilities of its utility-scale, liquid-cooled LUNA2000-4.5 MWh (LUNA2000-4472-2S) product and potential spread out to neighboring units.

Four Smart String & Grid Forming ESSs (containers A, B, C, and D) used in the ignition test were actual mass-produced products. Charged to 100% state of charge (SOC), they were deployed according to the minimum maintenance and safety clearances required for a plant.

In real-world safety incidents, it is often a single cell that leads to the release of combustible gases in the container, potentially resulting in fire or explosion. However, in Huawei’s Smart String & Grid Forming ESS (container A), thermal runaway was initiated in 12 cells without an incident.

The system’s combined defense mechanism—positive pressure oxygen barrier and directional smoke exhaust duct—effectively vented combustible gases, the manufacturer reported. Manual ignition did not trigger fire or explosion, verifying the ESS’s ability to prevent fire and fault spread at the battery pack level.

To simulate large-scale burning scenarios, the test progressively increased the number of thermal runaway cells until the entire battery pack was affected while providing maximum oxygen supply to create stricter combustion conditions. Despite these challenges, the highest cell temperature in adjacent containers B, C, and D reached only 47°C—far below the thermal runaway threshold.

Post-test disassembly confirmed the integrity of the ESS body, fire-resistant layer, and internal battery packs, Huawei said.

The manufacturer also reported a slow fault progression as one of the product’s key safety features. The test showed that Huawei’s ESS (container A) delayed fire ignition for seven hours in extreme scenarios, even as the number of thermal runaway cells increased.

Such delayed propagation would allow emergency personnel time for early intervention, mitigating risks for personnel and property.

Large-scale fire testing, which replicates real-world power plant fire scenarios, are not mandatory in codes and standards applicable to BESS projects. However, several manufacturers, including Sungrow, Wärtsilä, and Fluence, have conducted such testing to demonstrate that safety incidents can be limited to a single enclosure and not spread to neighboring units or other equipment.

In its ignition test, Huawei used four utility-scale BESS units. This was previously done by Sungrow, which in November 2024 conducted a fire test on 20 MWh of BESS. The exercise involved four liquid-cooled 5 MWh Powertitan 2.0 storage systems and came with a price tag of $4.2 million. At the time, Sungrow claimed it to be to be industry-first test at that scale.

*This article was updated on February 27 to specify the model of utility-scale product used in the test as LUNA2000-4.5MWh (LUNA2000-4472-2S).