A National Renewable Energy Laboratory study released in January finds that the potential for adding floating solar panels at reservoirs in the U.S. is significant. Reservoirs in the U.S. could host enough floating solar panels to generate up to 1,476 terawatt hours, it said.
For the study, Evan Rosenlieb and Marie Rivers, geospatial scientists at NREL, as well as Aaron Levine, a senior legal and regulatory analyst at NREL, quantified for the first time exactly how much energy could be generated from floating solar panel projects installed on federally owned or regulated reservoirs, NREL said on Jan. 14.
“And the potential is surprisingly large: Reservoirs could host enough floating solar panels to generate up to 1,476 terawatt hours,” NREL said in a news release.
“That’s a technical potential,” Rosenlieb said, meaning the maximum amount of energy that could be generated if each reservoir held as many floating solar panels as possible. “We know we’re not going to be able to develop all of this. But even if you could develop 10% of what we identified, that would go a long way.”
Levine and Rosenlieb have yet to consider how human and wildlife activities might impact floating solar energy development on specific reservoirs. But they plan to address this limitation in future work, NREL said.
The study “provides far more accurate data on floating solar power’s potential in the United States. And that accuracy could help developers more easily plan projects on U.S. reservoirs and help researchers better assess how these technologies fit into the country’s broader energy goals,” NREL said.
Floating solar panels, come with many benefits, it said.
“Not only do these buoyed power plants generate electricity, but they do so without competing for limited land. They also shade and cool bodies of water, which helps prevent evaporation and conserves valuable water supplies.”
“But we haven’t seen any large-scale installations, like at a large reservoir,” Levine said. “In the United States, we don't have a single project over 10 megawatts.”
Previous studies have tried to quantify how much energy the country could generate from floating solar panels. But Levine and Rosenlieb are the first to consider which water sources have the right conditions to support these kinds of power plants, NREL noted.
In some reservoirs, for example, shipping traffic causes wakes that could damage the mooring lines or impact the float infrastructure. Others get too cold, are too shallow, or have sloping bottoms that are too steep to secure solar panels in place.
“And yet, some hydropower reservoirs could be ideal locations for floating solar power plants,” NREL said in the news release.
A hybrid energy system that relies on both solar energy and hydropower could provide more reliable and resilient energy to the power grid. If, for example, a drought depletes a hydropower facility’s reservoir, solar panels could generate energy while the facility pauses to allow the water to replenish, it noted.
And, to build new pumped storage hydropower projects, some developers create entirely new bodies of water. These new reservoirs are disconnected from naturally flowing rivers, and no human or animal depends on them for recreation, habitat, or food (at least not yet).
In the future, the researchers plan to review which locations are close to transmission lines or electricity demand, how much development might cost at specific sites, whether a site should be avoided to protect the local environment, and how developers can navigate state and federal regulations.
The team would also like to evaluate even more potential locations, including other, smaller reservoirs, estuaries, and even ocean sites.
The research was funded by the Solar Energy Technologies Office and the Water Power Technologies Office in DOE’s Office of Energy Efficiency and Renewable Energy.
Access the study to learn more about the immense potential for floating solar plants in the United States, or visit AquaPV to access the data on specific reservoirs.
NREL is the U.S. Department of Energy's primary national laboratory for renewable energy and energy efficiency research and development.
Public Power and Floating Solar Panels
Public power utilities in the U.S. have been pursuing floating solar projects.
Florida public power utility OUC recently reported that its largest floating solar array – and the largest in the Southeast U.S. – will soon be deployed on a Department of Transportation retention pond in Southeast Orlando.
The 2 MW system will be OUC’s third floating solar project, featuring more than 3,700 panels to send electricity back into the grid.
In January 2021, the public power City of Healdsburg, Calif., completed the 4.78-megawatt photovoltaic solar array for the recycled-water ponds at its Wastewater Treatment Facility. Healdsburg staff conceived the project with the support of the Northern California Power Agency.
Terry Crowley, Healdsburg’s Utility Director, in 2023 gave a tour of the floating solar project for attendees of the Northwest Public Power Association’s Northwest Innovations in Communications Conference, which was held in Santa Rosa, Calif.
Also in California, public power utility Turlock Irrigation District is pursuing Project Nexus, which includes the installation of solar panel canopies over various sections of Turlock Irrigation District’s irrigation canals.
Project Nexus serves as a Proof of Concept to pilot and further study solar over canal design, deployment, and co-benefits on behalf of the State of California using TID infrastructure and electrical grid access.
The Project at both locations is expected to be completed and commissioned by 2025.