Revolutionizing Data Centers: New Utility-Scale Battery Solution Eliminates Need for Traditional UPS Infrastructure

Here comes a utility-scale battery designed for data centers that doesn’t require uninterruptible power supply infrastructure

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**June 11, 2025**
**By Paul Gerke**
**5 min read**

**Source:** FlexGen

As the saying goes, “with great power comes great responsibility.” This adage rings especially true in today’s world, where the energy demands of resource-intensive and always-on data center operations are on the rise. The increasing energy needs driven by artificial intelligence (AI) training, high-density computing, and variable loads are pushing the boundaries of traditional power infrastructure in data centers, making a modern solution essential. Two industry leaders believe they have found one.

FlexGen Power Systems, a battery energy storage company, has teamed up with Rosendin, the largest employee-owned electrical contracting firm in the United States. Together, they are developing innovative technology within utility-scale Battery Energy Storage Systems (BESS) specifically designed to support data center operations without the need for conventional uninterruptible power supply (UPS) infrastructure.

### The Project

FlexGen and Rosendin are working on a utility-scale battery solution that will be installed outside of data center buildings as part of a medium-voltage (1,000V to 35,000V) infrastructure. They aim to introduce a groundbreaking BESS that serves as a reliable, high-performance alternative to traditional UPS systems located outside data centers. This approach simplifies system architecture and reduces capital expenditures.

The project will incorporate Rosendin’s patented BESSUPS design and methodology, along with FlexGen’s patents for Soft Grid Interconnection and Island Grid Transient Frequency Stabilization. Additionally, the initiative will utilize FlexGen’s Innovation Lab to integrate its powerful HybridOS energy management system, enhanced by Rosendin’s extensive experience in data center delivery and thought leadership in energy storage.

According to Rosendin, the BESSUPS system offers several advantages, including delivering reliable CEBMA-quality power on a large scale without relying on generators for clients who wish to decarbonize. This method also provides significant benefits to end-users by offering dispatchable power upon demand and enabling advancements in power dispatch methods and consumption dynamics with proven utility-scale systems.

Through this collaboration, FlexGen and Rosendin are conducting real-world, grid-connected tests to validate the following:

– Existing grid-forming Power Conversion System (PCS) technology can meet fast-response and waveform control requirements.
– Modifications to the current AC Power Conversion System (PCS) firmware enhancements from Original Equipment Manufacturers (OEMs) will facilitate seamless UPS replacement functionality.
– Utility-scale BESS can support mission-critical loads, improve resiliency, and simplify the transition between grid-connected and islanded modes.

“As data centers scale to meet the exponential demand from AI and hyperscale computing, we need to rethink how we deliver power resilience across the modern data center campus,” stated Pasi Taimela, Chief Innovation Officer of FlexGen. “This collaboration with Rosendin enables us to introduce a smarter, leaner, and more responsive approach to energy design in data centers that requires no redesigns within the facility—where battery systems provide both power quality and grid services without compromise.”

“Data center developers are seeking scalable and flexible power solutions that do not sacrifice performance,” added Bill Mazzetti, Senior Vice President of Rosendin. “With FlexGen’s Innovation Lab and our expertise in constructing complex electrical systems, we are well-positioned to validate a solution that empowers our clients to build faster, smarter, and with greater confidence.”

Utilities in the Midwestern United States are facing significant challenges from increasingly extreme weather, aging infrastructure, and the ongoing transition to renewable energy while ensuring grid reliability. State decarbonization regulations complicate the process of bringing power generation online. As utilities shift from fossil fuels to cleaner alternatives, they also contend with supply chain issues, labor shortages, and new cybersecurity risks. Service providers must modernize their infrastructure to meet rising demand while keeping costs reasonable—a daunting task for any utility.

To address these challenges, a new regional DISTRIBUTECH event, DTECH Midwest, will focus on the specific issues faced by the power industry in the Midwest, offering tailored content for municipal and cooperative utilities. Registration is now open; join us from July 14-16, 2025, in Minneapolis, MN! Learn more about what you can expect [here](#).

### The Benefits of an Improved BESS

BESS configured as interactive UPS alternatives present substantial value throughout the development lifecycle. They help reduce electrical footprints and construction complexities while enhancing energy efficiency and operational resilience. Flexible interconnection is emerging as an effective way to expedite project timelines, with paired battery storage being quicker to deploy than co-located gas generation. This makes the solution particularly appealing for data center developers.

Rosendin and FlexGen believe that the results from this integration will inform system architecture standards, procurement planning, and large-scale deployment strategies for future data center projects and suppliers across the industry. Last December, FlexGen announced plans to collaborate with Eos Energy, a manufacturer of zinc-based long-duration energy storage systems, to introduce the first domestic BESS option in the U.S. The companies signed a joint development agreement to create America’s first fully-integrated domestic storage solution that combines Eos’ Z3 zinc-bromine batteries with FlexGen’s HybridOS energy management system and a domestic inverter and transformer package. The outcome will be a customizable solution suitable for various applications, ranging from grid-scale to behind-the-meter energy storage systems.