A long-term study carried out by Dutch marine biologists 7.4 miles from The Hague found that grey and harbor seals use an artificial solar farm floating in the water as a haul-out.
Grey and harbor seals were documented resting on the floating structures using above-water time-lapse imagery, supplemented by
maintenance sightings.
The researchers recorded seals using the solar deck all year round for resting purposes, until high waves drove them back to the water.
Turning floating solar platforms into offshore haul-out sites
Environmental scientists from Wageningen University & Research conducted the study at the North Sea demonstrator project site to determine the long-term environmental impact on marine life.
Solar buoy platforms, installed far away from sandbanks, gave the seals a comfortable place to conserve energy above the water.
Grey seals and harbor seals started hanging out on low-lying pontoon edges out of the water to dry themselves.
Choosing these above-water locations helped the marine mammals to rest without having to swim seven miles back to land after foraging dives.
The solar platform acted as a resting station for the seals out in the open sea.
Evaluating wave limits on marine mammal resting behavior
Gentle waves made it possible for the seals to rest undisturbed on the platforms in periods of calm weather.
When winds and wave heights offshore increased, the resting conditions turned out to be far from ideal.
Seals resting on the platform decks were constantly hit by waves splashing over the edges of pontoons, which meant the purpose of resting was no longer served.
The strong turbulence of the water surface finally made the seals leave the platform decks and return to the ocean.
The physical state of the ocean was a major factor in whether the seals benefited from the platforms or not.
Tracking underwater ecological shifts beneath buoyant solar arrays
Environmental monitoring groups conducted measurements on water quality, light penetration, underwater acoustics, and biofouling throughout the deployment area.
The opaque photovoltaic panels cast deep shadows on the water column and greatly reduce the natural sunlight reaching the shallow marine environment.
The low levels of light may end up affecting algal photosynthesis.
The submerged anchoring cables and pontoon undersides also provide artificial reefs for marine invertebrates, algae, and schooling fish.
The floating energy equipment, therefore, may change the the marine food chains above and below the surface of the ocean.
Balancing offshore clean energy development against marine habitat changes
Europe’s energy companies intend to co-situate their floating solar structures in their offshore wind farm concessions in the North Sea basin.
The incorporation of solar systems in offshore wind farms allows the maximum use of space in the sea, along with the convenience of connecting to pre-existing underwater power lines.
Thousands of floating solar panels installed on the open water change the dynamics of waves, sunlight, and animal behavior.
Government agencies need thorough environmental monitoring data before issuing licenses for utility-scale ocean solar projects.
Expansion of offshore solar installations leads to new challenges for marine life around the world.
Defining the limits of initial North Sea pilot studies
According to field studies, small floating solar power systems serve as temporary haul-out platforms for grey and harbor seals at miles-out offshore locations.
The information obtained from Wageningen University & Research‘s small pilot site cannot guarantee the safety of the environment for any future development of commercial solar utility plants.
Scientists are not able to prove if large multi-megawatt solar plants increase or reduce marine biodiversity and affect the migration paths of other wildlife.
Though the small pilot site shows biological interactions immediately, further research is needed to estimate the real ecological safety of utility plants.
Floating solar farms provide increasing opportunities for renewable energy development, but first, the safety of large commercial solar farms needs to be demonstrated.
The full study can be read here: Nalmpanti, M., Heuvel, L. v. d., Helvert, F. v., & Vlaswinkel, B. (2026). Marine Megafauna Interactions with Offshore Solar Infrastructure: First Ecological Observations from the North Sea. Sustainability, 18(3), 1646. https://doi.org/10.3390/su18031646
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