Floating PV Systems Show Minimal Impact on Water Quality – May Even Offer Climate Resilience Benefits

image from Fraunhofer-Institut für Solare Energiesysteme ISE

Over a three-year period, researchers from the Fraunhofer Institute for Solar Energy Systems ISE and the University of Freiburg investigated the ecological impact of three floating photovoltaic (FPV) systems installed on artificial lakes in Germany, Switzerland, and the Netherlands. Their findings, part of the *FPV4Resilience* project, reveal no significant negative effects on water quality—despite differing system sizes, designs, and climatic conditions.

Key measurements taken at the sites, including oxygen levels and nutrient composition, consistently fell within normal variation. “The slight changes in water temperature and the presence of mussel colonies may even support water ecosystems in the face of climate change,” explains project lead Dr. Konstantin Ilgen from Fraunhofer ISE.

The floating PV systems were found to reduce summer water temperatures by limiting sunlight penetration, while helping retain heat during winter. These effects were most pronounced at the largest installation in Sekdoorn, Netherlands, where east-west facing modules float on metal frames supported by pontoons.

Interestingly, mussels colonizing the underwater structures helped filter the water and reduce phosphorus levels—though their respiration slightly lowered oxygen content. Birds also adapted well: 25 species, including the Northern Lapwing and Common Snipe, were observed using the Dutch installation for resting, hunting, and nesting.

The study underlines the complexity of interactions between floating PV, biodiversity, and local human activity. “In many cases, human influences had a greater impact than the FPV systems themselves,” Ilgen notes. As such, the team cautions against applying these findings universally without further research.

The *FPV4Resilience* project was supported by the Sustainability Center Freiburg (LZN), with Dr. Ilgen receiving additional funding from the German Federal Environmental Foundation (DBU) through a PhD scholarship (*Promotionsstipendium*).

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