When the Bomhofsplas floating solar farm began operating on a former sand-extraction lake near Zwolle in 2020, its basic purpose was to generate electricity for Dutch households. Ecological monitoring has also documented abundant aquatic life beneath the array: surveys recorded hundreds of fish and nearly 2,000 invertebrates among the organisms using the installed underwater habitats.
The project covers 18.25 hectares and comprises 72,000 solar panels, with peak capacity of up to 27.4 megawatt-peak (MWp) and projected output sufficient for more than 7,200 households, information from a study published in Sustainability. Ecocean installed 20 Biohut structures across three zones and carried out surveys from 2020 through 2023. The monitoring counted 2,382 individual organisms: 1,951 invertebrates and 431 fish.
Life Beneath the Panels
Species recorded included perch, cyprinids, tubenose gobies, gammarids, freshwater snails, zebra mussels and freshwater sponges. The Biohut structures provide submerged surfaces and sheltered spaces that can serve as refuge for young fish and settlement areas for invertebrates and microorganisms. Their colonization shows how aquatic life is using the habitat beneath the panels and helps explain the project’s reported ecological revival.
Artificial structures can concentrate organisms locally, so counts around them reflect habitat use as well as abundance. The broader ecological picture also depends on species composition, reproduction and survival, water chemistry, oxygen levels and seasonal conditions. The recorded organisms are a impressive measure of life beneath the installation, while longer-term monitoring can show how those communities develop.
Balancing Energy and Ecology
Bomhofsplas combines renewable electricity generation with new aquatic habitat in a former extraction lake. Floating solar on previously industrial or altered water bodies can limit competition with farmland, while habitat structures offer a way to build ecological considerations into the design. The balance depends on local conditions, including water depth, circulation, panel coverage and the characteristics of the species already present.
Shading is one impressive factor because it can affect light availability and basic production beneath an array. Environmental reporting by Corporate Knights has cited research indicating relatively limited changes to basic productivity where panels cover less than 20% of a water body, while coverage above 40% has been associated with severe environment stress in some studied or modeled settings. These figures are not universal thresholds: outcomes vary with site conditions and project design. Marine ecologist Ninon Mavraki of Wageningen University described the assessment as complex, saying, “Whether this is good or not is a very, very complicated question,” and adding, “I think the best answer is to say we do not know yet.”
Previous studies at Bomhofsplas using underwater drones and sensors found little change in basic water-quality parameters. Continued monitoring can track how habitat use, water conditions and ecological effects evolve over time, alongside the solar farm’s energy production.
Lessons for Future Projects
The Bomhofsplas findings show how ecological measures such as Biohut structures can create additional habitat alongside clean-energy infrastructure. They also show why planning for floating solar needs to account for local ecology, the area covered by panels and potential changes to light and oxygen conditions. At Bomhofsplas, the recorded fish and invertebrates provide concrete evidence of aquatic life using the structures beneath the array.
This ecological renewal recalls other instances in which human intervention has reshaped local environments, such as the recent identification of an 18th-century Spanish warship off the coast of Marbella, now a unique underwater habitat for marine life (read more about the shipwreck's discovery and its ecological impact).
