Floating solar panels show promise, but environmental impacts vary by location, study finds

Floating solar panels appear to be a promising clean energy solution with environmental benefits, but a new study published in Limnological finds that these effects vary considerably depending on where 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 systematically cooled surface waters and changed the water temperature at different layers of the reservoirs. However, the panels also introduced increased variability in habitat quality for aquatic species.

“Different reservoirs will respond differently based on factors like depth, circulation dynamics and which fish species are important for management,” said Evan Bredeweg, lead author of the study and former postdoctoral researcher at Oregon State. “There is no universal formula for designing these systems. It’s a question of ecology, it’s complicated.”

While the floating solar panel market is established and growing in Asia, it remains limited to the United States, primarily to small pilot projects. However, a study released earlier in 2025 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 per year, or enough to power about 100 million homes.

Floating solar panels offer several advantages. The cooling effect of water can increase panel efficiency by approximately 5-15%. The systems can also be integrated into existing hydroelectric and transportation infrastructure. They can also help reduce evaporation, which is especially helpful in hotter, 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 variability of ecological responses to floating PV deployment is crucial to informing regulatory agencies and guiding sustainable energy development,” Bredeweg said.

The new study used advanced modeling techniques to assess the implications of deploying floating solar panels on entire reservoirs. The 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- and cold-water fish species. For example, cooler water temperatures in summer generally benefit cold-water species, although this effect is more pronounced when panel coverage exceeds 50%.

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

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

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