US-based energy storage company Viridi has received UL 9540 listing for its RPSLinkIN 480V battery energy storage system, with certification granted by TÜV Rheinland.
The UL 9540 standard is one of the most widely recognised safety benchmarks for energy storage systems in North America, particularly for installations in occupied buildings and critical infrastructure.
According to the company, the system achieved certification following UL 9540A Edition 5 unit-level testing under residential, indoor, floor-mounted conditions, described as the most stringent of the test scenarios. The RPS50kWh pack met all five performance criteria, with no smoke, gas or fire detected during testing, and no measurable heat increase in adjacent battery units.
As a result, the system can be deployed indoors without additional fire suppression or secondary safety systems, which are typically required for lithium-ion battery installations.
Viridi’s proprietary lithium-ion technology
The RPSLinkIN system is based on Viridi’s proprietary lithium-ion technology designed to prevent thermal propagation. The company says this enables installation in occupied and space-constrained environments, including hospitals, educational facilities, industrial sites and multi-residential buildings.
Jon M. Williams, CEO of Viridi, said: “Achieving UL 9540 Listing, utilising UL’s strictest indoor residential test, is a major milestone for Viridi and for the broader energy storage industry. Safety has been one of the primary barriers to scaling battery storage, particularly in critical infrastructure and occupied environments. With RPSLinkIN, we’re enabling organisations to deploy indoor energy storage systems where it wasn’t previously possible—unlocking new opportunities for resilience, cost savings, and decarbonisation, and representing a fundamental shift in how and where battery systems can be deployed.”
The certification builds on a series of deployments in mission-critical environments. These include installations at Oak Ridge National Laboratory and a 600kWh indoor system at the Hauptman-Woodward Medical Research Institute. In Erie County, New York, the system has also been used at a wastewater pumping station, providing up to 90 hours of backup power while replacing diesel generators.
Viridi said the listing could support wider adoption of distributed energy systems and virtual power plants by reducing safety and permitting constraints associated with conventional battery storage systems.
