Floating solar panels show promise, but environmental impacts vary 

Peer-Reviewed Publication

Oregon State University

News Release 17-Nov-2025

Floating solar panels are emerging as a promising clean energy solution with environmental benefits, but a new study finds those effects vary significantly depending on where the systems are deployed.

Researchers from Oregon State University and the U.S. Geological Survey modeled the impact of floating solar photovoltaic systems on 11 reservoirs across six states. Their simulations showed that the systems consistently cooled surface waters and altered water temperatures at different layers within the reservoirs. However, the panels also introduced increased variability in habitat suitability for aquatic species.

“Different reservoirs are going to respond differently based on factors like depth, circulation dynamics and the fish species that are important for management,” said Evan Bredeweg, lead author of the study and a former postdoctoral scholar at Oregon State. “There’s no one-size-fits-all formula for designing these systems. It’s ecology - it’s messy.”

While the floating solar panel market is established and growing in Asia, it remains limited in the United States, mostly to small pilot projects. However, a study released earlier this year by the U.S. Department of Energy’s National Renewable Energy Laboratory estimated that U.S. reservoirs could host enough floating solar panel systems to generate up to 1,476 terawatt-hours annually, enough to power approximately 100 million homes.

Floating solar panels offer several advantages. The cooling effect of the water can boost panel efficiency by an estimated 5 to 15%. The systems can also be integrated with existing hydroelectric and transmission infrastructure. They may also help reduce evaporation, which is especially valuable in warmer, drier climates.

However, these benefits come with questions about potential impacts on aquatic ecosystems, an area that has received limited scientific attention.

“Understanding the environmental risks and the variability in ecological responses to floating photovoltaic deployment is crucial for informing regulatory agencies and guiding sustainable energy development,” Bredeweg said.

The new study used advanced modeling techniques to assess the implications of floating solar panel deployment on entire reservoirs. Researchers examined reservoirs in Oregon, Ohio, Washington, Idaho, Tennessee and Arkansas, analyzing two-month periods in both summer and winter.

They found that changes in temperature and oxygen dynamics caused by floating solar panels can influence habitat availability for both warm-water and cold-water fish species. For instance, cooler water temperatures in summer generally benefit cold-water species, though this effect is most pronounced when panel coverage exceeds 50%.

The researchers note the need for continued research and long-term monitoring to ensure floating photovoltaic systems support clean energy goals without compromising aquatic ecosystems.

“History has shown that large-scale modifications to freshwater ecosystems, such as hydroelectric dams, can have unforeseen and lasting consequences,” Bredeweg said.

Co-authors of the paper include Ivan Arismendi of Oregon State’s Department of Fisheries, Wildlife, and Conservation Sciences; Sarah Henkel of the Hatfield Marine Science Center at Oregon State; and Christina Murphy of the U.S. Geological Survey’s Maine Cooperative Fish and Wildlife Research Unit.