Hefei, China, October 21, 2026 — Sungrow, a global leader in photovoltaic inverters and energy storage systems, announced that its latest The battery energy storage system (BESS) PowerTitan 3.0 successfully completed a large-scale fire test conducted in accordance with the latest applicable requirements of UL 9540A: 2026 and CSA/ANSI C800-2025, making itthe industry's first BESS with stacked-cell and AC-block design to successfully pass such a test. From PowerTitan 1.0 to 3.0, all three generations passed the large-scale fire test on the first attempt.

With the participation of international organizations, including UL Solutions, Fire Risk Alliance (FRA), and Jensen Hughes (JH), the test evaluated the system’s ability to contain a severe thermal runaway event and prevent it from spreading to adjacent BESS containers and the medium-voltage substation.

Tested under challenging real-world operating conditions

The test setup replicated the block layout of a real utility-scale BESS system, including a 28.56 MWh fully liquid-cooled PowerTitan 3.0 BESS and a 7.4 MW medium-voltage substation (MVS). PowerTitan 3.0 features stacked high-energy-density cells and an integrated block AC architecture, combining the battery system and the DC/AC power conversion unit in a single 20-foot container.

To further verify the system design's safety, the BESS was charged to 100%. The initiating container and the adjacent container were installed tightly against each other, back to back. MVS was also included in the test configuration. All active fire suppression systems and the thermal management system were disabled, and the rooftop pressure relief panels of the initiating container were fully opened to maximize ventilation and oxygen access. The test focused on the system's inherent ability to contain thermal runaway.

All smoke and fire emissions generated during the event were collected and routed through a dedicated purification system. The collected gases were fully treated, and no untreated smoke was released directly into the environment.

Thermal runaway did not propagate

The test successfully demonstrated that thermal runaway Did not spread from the original BESS container to any adjacent containers or MVS.

The test lasted 7.5 hours under continuous observation. The peak internal temperature in the initiating container, designated as Container A, reached 1259.8 °C, and the maximum cell temperature in the adjacent containers remained below the thermal runaway threshold per UL 9540A: 2026.

Despite the intensity and duration of the fire, container A maintained structural integrity. The adjacent containers B, C, D, and E also remained structurally intact, with no deformation. Even after the fire test, the containers remained structurally intact and could be lifted as complete units.

At full charge, close proximity, and maximum ventilation, PowerTitan 3.0 localized the thermal event within the initiating container and prevented it from escalating into a multi-container event. The results demonstrate stable, reliable, and controllable system performance under extreme conditions and are an important step in validating the safety of BESS platforms with higher energy density.

Three generations. All successfully tested. Simulation matches reality.

From PowerTitan 1.0 and 2.0 to PowerTitan 3.0, all three generations have successfully passed large-scale fire tests on the first attempt, enabling Sungrow to build an extensive database on thermal runaway and fire behavior. Before the physical test, PowerTitan 3.0 underwent simulation-based evaluation across hundreds of application scenarios and operating conditions using Sungrow's simulation platform is the largest of its kind in the world. The simulated fire intensity and development trends closely matched those recorded during the physical test, confirming the model's ability to predict fire behavior under extreme conditions.

“This test was aimed at verifying our safety solutions under real extreme conditions", — said Roger Li, general manager of the utility-scale project product line at Sungrow Energy Storage business unit. "Safety must be built into the product from the very beginning. Modeling helps predict how the system will behave, while large-scale fire tests verify these predictions in practice. Safety of energy storage systems is not only about cell safety. It is the result of the combined action of many factors, including cell characteristics, system integration, thermal management, structural protection, engineering design, and much more.”

Benjamin Liu, engineering development manager at UL Solutions, commented: "Sungrow started with a safety-by-design principle, used preliminary assessments to predict fire behavior, and then validated these predictions during a large-scale fire test. The test results showed that the design was able to contain the fire and prevent its spread, helping to significantly reduce potential damage.”

By combining engineering solutions with safety-by-design principles, predictive modeling, and large-scale physical testing, Sungrow is establishing a robust, evidence-based approach to BESS safety. For project owners, investors, insurers, and emergency responders, this provides a stronger technical foundation for assessing fire risks, planning emergency response, and protecting critical assets throughout the project lifecycle.