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In a sun-drenched Nevada desert, the Gemini project became America’s largest dispatchable single-phase solar + storage system, powering up to 10% of Nevada’s peak demand. This POWER Top Plant award winner demonstrates how innovative financing, tribal partnerships, and environmental stewardship can be part of transformational clean energy infrastructure.
Clark County, Nevada, presents a unique convergence of solar resource and energy demand that makes it one of the nation’s premier locations for utility-scale solar development. Nevada enjoys an average of 300 sunny days annually, with average peak sun hours extending up to seven hours during certain times of the year. The Las Vegas area, specifically, which serves as the economic heart of Clark County, receives 6.51 kilowatt-hours per square meter per day (kWh/m2/day) of solar insolation, which is about 35% more than the typical U.S. city. Compared to places like Seattle (3.57 kWh/m2/day) or Chicago (3.14 kWh/m2/day), Las Vegas is a solar goldmine.
This exceptional solar irradiance, combined with Nevada’s vast open desert landscape and minimal cloud cover, creates optimal conditions for capturing and converting sunlight into clean electricity. Yet, despite the region’s solar promise, only 13.69% of the state’s electricity was reportedly supplied by solar energy in January 2022 when the Nevada Governor’s Office of Energy published its annual Status of Energy Report.
Gemini Project Pairs Solar and Storage
Considering the potential Clark County held, Quinbrook Infrastructure Partners and Primergy announced on April 25, 2022, the final close of a monumental $1.9 billion deal for the Gemini Solar + Storage project, which the group planned to site in the county. The Gemini debt financing consisted of $1.3 billion in credit facilities, including a construction/term loan, tax equity bridge loan, and letter of credit facility. The Gemini financing included $532 million in tax equity commitments, which was believed to be the largest single-asset tax equity solar financing ever completed in the U.S., provided by Truist Bank and Bank of America. The construction facilities were led by four coordinating lead arrangers, KeyBanc Capital Markets Inc., MUFG Bank Ltd., Bank of America N.A., and Norddeutsche Landesbank Girozentrale, New York Branch. The coordinating lead arrangers successfully syndicated the credit facilities to 19 lenders, and Quinbrook and Primergy arranged the $95 million mezzanine debt facility from Voya Investment Management.
The project’s name, “Gemini,” aptly captures the essence of this groundbreaking energy installation. In astronomy, Gemini represents the constellation of the twins—two bright stars that shine together in the night sky. Similarly, the Gemini Solar + Storage project brings together two complementary energy technologies that work in perfect harmony: massive solar arrays that capture the desert sun’s abundant energy during the day, and sophisticated battery storage systems that preserve and deliver that clean power when darkness falls.
Gemini is a 690-MWac/966-MWdc solar photovoltaic (PV) array and a 380-MW/1,416-MWh battery storage project. It was the largest single project of its kind in the U.S. when it began construction.
In This Issue
Full issue“The Gemini project was led by Primergy, which managed all aspects of development from planning through construction, and continues to manage the operations,” the company told POWER. “Gemini was the largest single-phase, co-located solar plus battery energy storage system (BESS) project operating in the United States when it reached commercial operation in early 2024.”
The timing and scale of the Gemini project addressed a critical energy transition moment for Nevada. It highlighted the significant opportunity for solar + storage projects like Gemini to accelerate the state’s clean energy transition. Gemini’s ability to power approximately 10% of Nevada’s peak demand while providing 1,400 MWh of battery storage represented a transformational addition to the grid, offering both immediate renewable energy supply and the critical storage capacity needed to deliver clean power when the desert sun sets and Las Vegas comes alive. Notably, NV Energy specifically called out the Gemini project as an important contributor when the company filed its Annual Renewable Portfolio Report in April 2025, when it boasted of serving customers with almost 47% renewable energy in 2024.
Managing an Unprecedented Project
With 690 MW of solar and 380 MW of four-hour battery storage (see image gallery), Gemini is designed to maximize energy capture and system efficiency through a combination of advanced infrastructure and software. The project uses state-of-the-art energy management systems capable of directing power with millisecond-level precision, allowing it to respond dynamically to changing weather and grid conditions. Its 186 battery subsystems help capture clipped solar energy during periods of high generation and store it for use when demand peaks, creating a more consistent and reliable power supply for the grid.
To begin the project, a detailed procurement process was undertaken, and an experienced engineering, procurement, and construction (EPC) contractor was selected—Kiewit Power Constructors Co. Primergy also tapped into the local community. “The Moapa Band of Paiutes are one of our primary partners, and Gemini would not have been successful without their leadership, insight, and participation,” the company said. “With more than two decades of experience in solar development, including the first large-scale solar project ever built on tribal trust land, their generational knowledge of that land, regional infrastructure, and natural resources played a vital role in the project’s success.”
Primergy said it approaches tribal partnerships with deep respect and a commitment to long-term, equitable management. “From the beginning, we worked closely with the Moapa Band of Paiutes not only as landowners and project neighbors, but also as experts. Tribal members contributed their expertise throughout development and construction, serving as equipment operators, biological and cultural monitors, and more,” the company said. “With respect and recognition for the tribal councils of the past, the current tribal council has continued the vision to develop solar projects on their land in a way that will bring immediate benefits to their people, protect the land, and provide ongoing opportunities for future generations.”
Environmental stewardship was a core part of Gemini’s planning, construction, and operations. Primergy said it prioritized complete ecosystem management by designing the project to minimize its physical footprint and preserve as much of the native landscape as possible. This included leaving existing vegetation in place, contouring solar panel rows to follow the natural terrain, and using alternative site preparation methods that significantly reduced ground disturbance.
In the 24 months leading up to construction, Primergy implemented best practices to mitigate dust, stormwater runoff, and other environmental impacts, while also piloting new techniques for maintaining the solar array with minimal disruption to native plants. “We also utilized the latest research and design considerations to minimize the footprint of Gemini, reducing the overall project footprint by more than 20%, and access roads were minimized by 25% compared to traditional solar projects,” the company said.
Primergy said it implements responsible and efficient construction processes, such as using alternative site preparation methods, establishing narrow road corridors into the project site, and building appropriately spaced, raised rows of solar modules to ensure nearly 80% of the land on site remains open to the sky.
“Gemini demonstrates that efficient energy output and environmental concerns aren’t competing priorities,” Primergy said. “We proactively engaged the community and our environmental regulators through every step of project development. We have selected and deployed technologies that align those priorities.”
A Focus on Excellence and Efficiency
The attention to detail extended to other aspects of the project as well. “Our entire development strategy is built around quality and safety,” Primergy said. “We always have, and always will, prioritize safety above all else.” Managers were able to maintain Gemini’s project schedule through late stages of the pandemic, largely because they had well-trained professional construction members and by being proactive as significant global supply chain disruptions arose. “Having a trained workforce is invaluable to ensure a safe, well-constructed project site,” Primergy said.
Meanwhile, the project features a specially designed direct-current (DC)-coupled storage configuration, which enables the BESS to charge directly from the panels. This results in greater system efficiency and maximizes the capture and storage of solar energy directly onsite.
“Developing a DC-coupled storage configuration at this scale presented unique engineering and operational considerations, including balancing energy loads across more than 186 storage subsystems on site,” Primergy said. “This design delivers significant advantages, including allowing the battery energy storage system to charge directly from the solar panels, in turn, improving efficiency and maximizing on-site energy capture and storage. The project’s distributed architecture not only enhances fire safety and system resilience, but also supports greater operational availability, helping ensure consistent and reliable power delivery to the grid.”
From a grid perspective, Gemini functions similar to a gas plant—it’s a dispatchable resource delivering energy when it is needed most. That operational flexibility required close coordination across engineering, procurement, and construction, as well as ongoing collaboration with grid operators, regulators, and community stakeholders.
“We deeply value our partnerships with regulators and recognize that Gemini was a trailblazing project. We work closely with the utility to make sure that the asset is operated in accordance with their needs,” the company said. “The methods we implemented for Gemini have helped us identify opportunities to improve on our future projects.”
What makes Gemini truly unique is the integration of a first-of-its-kind battery storage system with large-scale solar. It sets new and timely benchmarks in sustainable infrastructure development and required innovative technical solutions, environmental stewardship, and precise alignment to keep all parts of the project on track.
Yet, Primergy’s approach extends beyond construction. “We’ve pioneered a holistic approach to responsible project development that considers complete ecosystem management, and collaborative partnerships with local and community stakeholders. This ensures the company minimizes environmental impact, and delivers lasting community benefits across jobs, training, and ongoing education in the benefits of large-scale clean energy infrastructure,” the company said.
To guide ongoing stewardship during the operational phase, Primergy is conducting a 30-year vegetation study in partnerships with the Bureau of Land Management and the U.S. Geological Survey. This research monitors vegetation, soil conditions, and sensitive species at the Gemini site to better understand how utility-scale solar development can coexist with desert ecosystems. The goal is to identify best practices that support both clean energy development and long-term biodiversity.
—Aaron Larson is POWER’s executive editor.
