FlexGen Power Systems LLC, a leading provider of battery energy storage solutions and energy management software, has partnered with Rosendin, the nation’s largest employee-owned electrical contracting company, to develop a utility-scale Battery Energy Storage System (BESS) aimed at supporting the evolving needs of modern data centers. This collaboration brings together proprietary technologies from both companies, including Rosendin’s patented BESSUPS design and FlexGen’s patented Soft Grid Interconnection and Island Grid Transient Frequency Stabilization solutions. The project will also leverage FlexGen’s HybridOS energy management system, integrated through its Innovation Lab, alongside Rosendin’s deep expertise in delivering complex data center and energy storage infrastructure.
The BESSUPS system offers a new approach by delivering high-quality, uninterrupted power at scale while eliminating the need for traditional generators. This is particularly beneficial for data center operators focused on decarbonization and energy efficiency. The system also allows for dispatchable power to be returned to the utility grid as needed, offering flexibility and helping meet shifting energy demands. Unlike conventional UPS systems installed inside data centers, the solution being developed by FlexGen and Rosendin is intended to be positioned externally, as part of the medium-voltage (1,000V to 35,000V) infrastructure. This architecture simplifies the overall design of data center power systems, reduces capital expenditures, and enhances performance.
As energy demands continue to rise due to AI workloads, high-density computing, and fast-changing loads, FlexGen and Rosendin’s approach aims to provide a scalable and reliable alternative to conventional power infrastructure. The companies are conducting grid-connected field tests to validate that existing grid-forming Power Conversion System (PCS) technologies can meet the strict response and waveform control requirements of data centers. These tests also assess whether firmware updates from PCS manufacturers can support seamless UPS replacement functionality. The system is being designed to handle mission-critical loads, strengthen operational resiliency, and ensure smooth transitions between grid-connected and islanded modes.
Pasi Taimela, Chief Innovation Officer of FlexGen, said in a statement, As data centers scale to meet exponential demand from AI and hyperscale computing, we need to rethink how we deliver power resilience across the modern data center campus. This effort with Rosendin enables us to bring to market a smarter, leaner, and more responsive approach to data center energy design that doesn’t require any redesigns inside the walls of the data center—one where battery systems provide both power quality and grid services without compromise.”
Bill Mazzetti, SVP of Rosendin, stated, “Data center developers are looking for scalable and flexible power solutions that don’t compromise on performance. With FlexGen’s Innovation Lab and our experience in building complex electrical systems, we’re positioned to validate a solution that helps our clients build faster, smarter, and with more confidence.”
Using BESS as a replacement for traditional UPS systems brings several benefits, including a reduced electrical footprint, simpler construction, increased energy efficiency, and enhanced operational stability. The project reflects both companies’ shared focus on addressing the most urgent challenges in the data center sector, including rising energy costs, demand for fast deployment, reliable switchover, and power quality assurance. The results of this initiative are expected to guide the future design and deployment strategies of data center infrastructure across the industry.
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