FlexGen and Rosendin Partner to Revolutionize Data Center Power with Innovative Battery Energy Storage Solution
In a groundbreaking collaboration, FlexGen Power Systems LLC (“FlexGen”), a leading provider of battery energy storage solutions and energy management software, has teamed up with Rosendin, the nation’s largest employee-owned electrical contracting company, to deliver a first-of-its-kind Battery Energy Storage System (BESS) tailored specifically for modern data centers. This innovative solution aims to replace traditional uninterruptible power supply (UPS) infrastructure with utility-scale battery systems, addressing the growing energy demands of AI training workloads, high-density computing, and fast-shifting loads while advancing sustainability goals.
A New Era of Data Center Power Solutions
The exponential growth of artificial intelligence (AI), hyperscale computing, and other data-intensive applications is pushing conventional power infrastructure to its limits. Traditional UPS systems, which have long been the backbone of data center resilience, are increasingly unable to meet the extreme power density and dynamic load requirements of today’s facilities. Recognizing this challenge, FlexGen and Rosendin have developed a utility-scale BESS solution that operates outside the data center building as part of the medium-voltage infrastructure (ranging from 1000V to 35000V). This approach not only simplifies system architecture but also reduces capital expenditures while enhancing performance and reliability.
At the heart of this collaboration is the integration of proprietary technologies from both companies. FlexGen brings its cutting-edge Soft Grid Interconnection and Island Grid Transient Frequency Stabilization patents, along with its powerful HybridOS energy management system, which optimizes energy usage and ensures seamless transitions between grid-connected and islanded modes. Meanwhile, Rosendin contributes its patented BESSUPS design and methodology, which enables CEBMA-quality power delivery on an uninterrupted basis at scale—without relying on generators for clients seeking to decarbonize their operations.
This innovative BESS solution offers several key advantages:
- Uninterrupted Power Delivery: The system provides CEBMA-grade power quality on a massive scale, ensuring reliable performance even during peak demand or grid disruptions.
- Dispatchable Power: End users can leverage the BESS system to dispatch power back to the utility upon request, enabling participation in grid services and creating additional revenue streams.
- Simplified Architecture: By moving the energy storage system outside the data center building, the solution reduces construction complexity and electrical footprint while maintaining high levels of resiliency.
Addressing the Challenges of Modern Data Centers
As AI workloads and hyperscale computing continue to drive unprecedented energy consumption, the need for smarter, more efficient power solutions has never been greater. Conventional UPS systems often struggle to keep pace with the rapid shifts in load demand and the extreme power densities required by modern data centers. Additionally, these systems typically rely on diesel generators for backup power, which conflicts with many organizations’ sustainability goals.
FlexGen and Rosendin’s BESS solution addresses these challenges head-on by offering a cleaner, more flexible alternative. By leveraging utility-scale battery technology, the system eliminates the need for traditional UPS infrastructure while providing superior power quality and resilience. Furthermore, the absence of generators aligns with the growing trend toward decarbonization, allowing data center operators to meet their environmental objectives without compromising on performance.
“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,” said Pasi Taimela, Chief Innovation Officer of FlexGen. “This effort with Rosendin enables us to bring to market a smarter, leaner, and more responsive approach to data center energy design—one where battery systems provide both power quality and grid services without compromise.”
Real-World Testing and Validation
To ensure the viability of this innovative solution, FlexGen and Rosendin are conducting real-world, grid-connected tests through FlexGen’s Innovation Lab. These tests aim to validate several critical aspects of the system:
- Fast Response and Waveform Control: Demonstrating that existing grid-forming Power Conversion System (PCS) technology can meet the stringent response times and waveform control requirements of mission-critical loads.
- Seamless UPS Replacement: Confirming that firmware enhancements to current PCS systems from OEMs can support UPS replacement functionality without interruption.
- Resilience and Mode Transition: Proving that utility-scale BESS can reliably support mission-critical loads and seamlessly transition between grid-connected and islanded modes.
These efforts will help establish new standards for system architecture, procurement planning, and large-scale deployment strategies, paving the way for broader adoption across the industry.
Why This Partnership Matters
For data center developers, the ability to deploy scalable and flexible power solutions without sacrificing performance is a game-changer. Bill Mazzetti, Senior Vice President at Rosendin, emphasized the importance of this initiative: “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.”
The BESSUPS system represents a significant leap forward in energy efficiency, operational resiliency, and cost-effectiveness. By reducing the electrical footprint, streamlining construction processes, and enhancing energy efficiency, this solution delivers value across the entire development lifecycle. Moreover, it aligns with the shared focus of FlexGen and Rosendin on solving the most pressing energy infrastructure challenges facing data centers today—speed, energy costs, reliable cutovers, and power quality.
About Rosendin
Rosendin, headquartered in San Jose, CA, is employee-owned and one of the largest electrical contractors in the United States, employing over 7,500 people, with average annual revenues of $2.9 billion. Established in 1919, Rosendin remains proud of our more than 100 years of building quality electrical and communications installations and value for our clients but, most importantly, for building people within our company and our communities. Our customers lead some of the most complex construction projects in history and rely on us for our knowledge, ability to scale, and dedication to quality. At Rosendin, we work to ensure that everyone can reach their full potential by building a diverse, safe, welcoming, and inclusive culture. For more information, visit www.rosendin.com.
Rosendin Energy Group (REG) is an EPC providing renewable, microgrid and mixed modality energy plant design, planning, and construction for a wide variety of energy projects. s. REG has installed nearly 9 GW of Utility-scale power throughout the U.S. and offers a comprehensive portfolio of construction services including design-build, substation and switchyard installation, plant construction, vertical tower wiring, overhead collection systems and transmission lines, AC & DC collection systems, and substation design and communications integration.
About FlexGen Power Systems, LLC
FlexGen provides industry-leading software and services for deploying, managing and optimizing battery energy storage systems. FlexGen leverages decades of engineering, procurement and software expertise to solve today’s toughest energy challenges that enable the transition to a modern electric grid. FlexGen HybridOS energy management software seamlessly integrates with any battery OEM and offers advanced analytics and AI-driven insights that allow energy storage owners to deploy diverse power market strategies and integrate various generation forms, enhancing grid stability and economic returns. With 1.5M hours of runtime and more than 10 GWh of energy storage systems enabled by FlexGen, we are trusted by the most technically and commercially demanding developers, utilities, government agencies, and industrial companies in the world.
