- Deflagration testing conducted by Fluence and DNV, along with large-scale fire testing by Fluence and CSA Group, confirms Gridstack Pro 2000, featuring Fluence’s U.S.-manufactured battery modules, as the first domestic content solution to exceed the industry’s top safety standards
Fluence Energy, Inc., a global market leader delivering intelligent energy storage, operational services, and asset optimization software, has announced the successful completion and passing of rigorous deflagration and fire safety testing for the first Gridstack Pro system. The fire test included Fluence’s U.S-manufactured battery modules, which began production in Utah earlier this year and recently achieved UL1973 certification. The modules, along with other U.S.-sourced components, are a key part of Fluence’s U.S.-manufactured product offering.
A series of dispersion and deflagration tests to evaluate the explosion mitigation features of Gridstack Pro 2000 was conducted at DNV’s Spadeadam Research and Testing in Cumbria, U.K., a world-leading fire and explosion research and testing facility. Dispersion testing verifies how quickly gases will dissipate from within the enclosure to prevent explosion conditions. Gases are accumulated within the test enclosure but are not ignited. Deflagration testing verifies explosion protection features, such as deflagration panels, work as designed. During deflagration testing, gases are intentionally ignited to cause deflagration. The results from the Gridstack Pro 2000 testing validate the deflagration vents and panels effectively mitigate explosion risks, meeting NFPA 68 and NPFA 855 requirements. A detailed report from DNV validates these safety performance results.
The large-scale fire test, conducted under the observation of the product testing, inspection, and certification organization CSA Group, significantly exceeded the requirements of the UL 9540A test standard. While UL 9540A unit level testing evaluates how thermal runaway may propagate through a battery system, it does not require actual fire conditions. The large-scale fire test on Gridstack Pro 2000, conducted at Safe Laboratories in North Carolina, involved a fully developed fire to validate enclosure separation distances, meeting the new large-scale fire test requirements in the upcoming NFPA 855 (2026). During testing, a fully populated enclosure burned without any fire suppression or firefighting efforts and self-extinguished without propagating to any neighboring enclosures or exposures. This worst-case scenario confirmed the system’s ability to mitigate fire risks and contain thermal events to the enclosure of origin. A detailed report from CSA validates these safety performance results.
“During the UL 9540A unit level test, Gridstack Pro 2000 with Fluence modules successfully contained thermal runaway to one module without propagating to additional modules, fire ignition, or deflagration,” said Chris Reed, CSA Group Product Safety Engineer. “Large-scale fire testing further reinforced the system’s safety credentials, demonstrating that no propagation occurred between enclosures when spaced at the minimum allowable distance, even under fully developed fire conditions.”
“This achievement marks a significant milestone for our Gridstack Pro line, designed with safety-first principles that underpin every Fluence solution,” said Rebecca Boll, Fluence SVP & Chief Product Officer. “The successful testing of Gridstack Pro 2000 demonstrates its strong safety performance and reliability, reinforcing customer and stakeholder confidence in our commitment to exceeding industry safety standards.”
In addition to validating fire containment performance, Fluence has taken the lead to exceed industry standards by collecting gas data during large-scale fire testing and conducting product-level plume modeling. Plume modeling analysis is used to better understand the composition and dispersion of smoke and gases generated during such events and support the development of safety guidelines for permitting authorities and first responders, with the goal of aligning emergency response measures with real-world conditions.
As a pioneer in deflagration and large-scale fire tests that have helped define safety standards since 2022, Fluence continues to lead the industry on safety. Fluence systems integrate advanced safety features, including incipient gas detection, fault detection, and deflagration panels, which work together to prevent, detect, and contain thermal events. These measures are intended, in the unlikely event of an incident, to minimize impacts, and reduce potential damage and downtime.
Fluence also engages proactively with permitting authorities and first responders by offering comprehensive training programs. These programs include instructor-led courses on battery energy storage safety and operations, covering topics such as system design, failure modes, and incident response. The goal is to prepare responders to address potential hazards safely and effectively.
