Floating Solar Farm in the Netherlands Becomes an Unexpected Nursery for Aquatic Life

A floating solar farm in the Netherlands is doing more than producing clean electricity. Beneath its panels, artificial underwater shelters have attracted hundreds of fish and nearly 2,000 invertebrates, creating signs of a functioning aquatic ecosystem inside a former sand-extraction lake.

The findings come from the Bomhofsplas floating solar project near Zwolle. Researchers monitored 20 underwater structures known as Biohuts between 2020 and 2023.

The Biohuts were designed to give young fish a safe place to hide, feed and grow. Over three monitoring campaigns, researchers recorded 431 fish and 1,951 invertebrates, along with zebra mussels and freshwater sponges attached to some of the structures.

That adds up to 2,382 observed organisms.

The result matters because floating solar is growing quickly around the world. Supporters see it as a way to generate renewable electricity without taking over farmland or undeveloped land. Critics worry that covering water with panels could reduce light, change water temperature and disturb wildlife.

Bomhofsplas shows a more useful answer.

Floating solar does not have to ignore ecology. It can be designed around it.

What Is Bomhofsplas?

Bomhofsplas is a former sand-extraction lake in the Dutch province of Overijssel.

The floating solar installation opened in 2020 and covers roughly 18 hectares of water. Project descriptions differ slightly on the exact panel count, placing it at around 72,000 to 73,000 solar panels, with an installed capacity of approximately 27.3 to 27.4 megawatts.

The project generates enough renewable electricity for around 7,000 to 8,000 homes, depending on the calculation used.

Those numbers made it one of Europe’s most prominent floating solar projects when it opened.

But its design was not limited to electricity production.

The developers included several features intended to reduce ecological disruption:

• The panels cover only part of the lake
• Wide spaces allow light to reach the water
• The system permits water movement beneath and around the installation
• The panels are anchored to the lake bed rather than the shoreline
• Biohuts were installed to support small aquatic species

That combination is important.

The project was not placed on the lake and then studied as an afterthought. Ecological features were included from the start.

How the Biohuts Work

Biohuts are underwater cages built to imitate some of the shelter and feeding functions found in natural habitats.

Each structure contains shell material in a central section. That material creates surfaces where algae, microorganisms and small invertebrates can grow.

Open protective sections on either side give juvenile fish space to move while making it harder for larger predators to reach them.

The design addresses a basic problem in altered water bodies.

Young fish need shelter.

Natural lakes often provide reeds, submerged plants, rocks, roots and shallow edges. A former industrial sandpit may have fewer of those features, especially in deeper or heavily modified sections.

The Biohuts add physical complexity where little existed before.

That creates:

• Hiding places
• Feeding areas
• Surfaces for organisms to attach
• Protection from larger fish
• A nursery habitat for juveniles

The idea is simple.

Give small organisms somewhere safe to live, and the food chain has a better chance to build around them.

Researchers Found a Growing Aquatic Community

The monitoring programme ran from 2020 through 2023.

Researchers carried out three ecological surveys and recorded three groups of fish: common perch, cyprinids and tubular-nosed goby.

They also documented invertebrates including gammarids and freshwater snails, as well as zebra mussels and freshwater sponges growing on the Biohut grilles.

By the end of the monitoring period, the structures had supported:

• 431 fish
• 1,951 invertebrates
• Three observed fish groups
• Multiple organisms at the base of the food chain
• Zebra mussels and freshwater sponges

The most important finding may not be the total number.

It is the type of organisms present.

Small crustaceans and other invertebrates are food for fish and larger animals. Their abundance suggests the Biohuts were not functioning as empty cages that fish occasionally visited.

They were supporting a broader biological system.

The monitoring team said the ecosystem appeared balanced and capable of supporting aquatic life.

That is a stronger result than simply finding a few fish beneath the panels.

The Solar Panels May Create Benefits Too

The Biohuts were the main focus of the biodiversity monitoring, but the floating panels themselves may influence the lake.

Solar panels create shade.

That can reduce evaporation, which may be useful in reservoirs and regions facing water stress. The water also helps cool the panels, potentially improving their performance during warm conditions.

Floating systems can also avoid some of the land-use conflicts associated with large ground-mounted solar farms.

A project built on an industrial water body does not need to replace farmland, forest or open habitat.

That does not mean floating solar has no environmental cost.

Too much coverage could reduce light reaching the water. It could affect oxygen levels, water temperature, algae and aquatic plants. Anchoring systems and maintenance activity can also create disturbance.

The lesson from Bomhofsplas is not that panels automatically improve lakes.

The lesson is that design choices matter.

Why Light and Water Flow Matter

The Bomhofsplas project includes gaps between panel sections and panels that allow some light to pass through.

That helps reduce the risk of turning the covered area into a dark, stagnant zone.

Aquatic ecosystems depend on light.

Sunlight supports algae and plant growth, which then supports insects, fish and other animals. Completely blocking light across a large part of a lake could disrupt that chain.

Water movement matters for similar reasons.

Good circulation helps distribute oxygen and nutrients. It also reduces the chance of isolated areas developing poor water quality.

Bomhofsplas was designed to leave room for both light penetration and water flow.

That does not guarantee zero impact.

It creates better conditions for limiting damage.

Bird Activity Was Also Reported Beneath the Panels

Earlier research into water quality at the site noted that bird sounds could be heard beneath the solar panels, raising the possibility that birds were using the structures for shelter or nesting.

That observation is interesting, but it should not be overstated.

Sound alone does not prove successful nesting or a long-term benefit to bird populations.

It does, however, suggest the installation is not an entirely lifeless industrial surface.

That is worth studying further.

Solar projects can create risks for birds. Reflective panels may sometimes be mistaken for water, and badly located projects can interfere with habitat or movement.

The right question is not whether solar is always good or always bad for wildlife.

It is whether a specific project has been planned, located and managed responsibly.

Floating Solar Solves a Land Problem

One reason floating solar is attracting attention is land scarcity.

Large solar farms require space. In densely populated countries such as the Netherlands, that can create conflict with farming, housing, nature conservation and industry.

Floating solar uses an existing water surface instead.

The best locations are often artificial or heavily modified water bodies, including:

• Quarry lakes
• Sand-extraction pits
• Irrigation reservoirs
• Drinking-water reservoirs
• Industrial ponds
• Hydropower reservoirs

These sites may already have grid connections, access roads or nearby energy infrastructure.

They can also provide a second use for land and water that is already serving an industrial or utility purpose.

Bomhofsplas is a clear example.

A former sandpit now produces renewable power while supporting local ownership and ecological research.

The Findings Are Promising, Not Universal

The results should be viewed with some caution.

This was one project in one lake.

The Biohuts were deliberately installed as habitat structures. The positive findings cannot automatically be credited to the solar panels alone.

Different lakes have different depths, temperatures, species, water chemistry and ecological conditions.

A floating solar project covering too much water or placed in a sensitive natural habitat could produce very different results.

Longer-term questions also remain:

• How do fish populations compare with areas outside the solar farm?
• Does the project change oxygen levels over time?
• What happens as panels and floating equipment age?
• Do invasive species benefit from the new structures?
• Are the observed fish surviving to adulthood?
• How does the lake respond during unusually hot summers?

These questions require continued monitoring.

Good results from three surveys are encouraging.

They are not the end of the research.

Better Design Can Reduce the Trade-Off

Renewable energy projects are sometimes presented as a choice between clean electricity and nature.

That is often a false choice.

Poorly designed projects can cause unnecessary damage. Better projects can reduce harm and sometimes create new habitat functions.

The practical steps are not mysterious:

• Use artificial or previously disturbed water bodies
• Limit the percentage of water covered
• Maintain light corridors
• Preserve water circulation
• Protect shorelines
• Avoid sensitive breeding areas
• Install habitat structures where appropriate
• Monitor water quality and biodiversity
• Change operations if harm appears

This approach costs more effort at the beginning.

It can prevent much larger problems later.

The Key Facts

• Bomhofsplas is a floating solar farm near Zwolle in the Netherlands
• It opened in 2020
• The project has roughly 27.3 to 27.4 megawatts of capacity
• It contains around 72,000 to 73,000 panels
• It can supply electricity equivalent to the needs of roughly 7,000 to 8,000 homes
• Twenty Biohuts were installed beneath different sections of the project
• Researchers monitored them between 2020 and 2023
• They observed 431 fish and 1,951 invertebrates
• Zebra mussels and freshwater sponges also colonized some structures
• The project includes design features intended to preserve light and water flow

The Bottom Line

Bomhofsplas is not proof that every floating solar farm helps wildlife.

It proves something more useful.

A renewable energy project can be designed to generate electricity while actively considering the ecosystem around it.

The panels produce power.
The Biohuts provide shelter.
The monitoring shows aquatic organisms are using that shelter.

That is the model worth copying.

Clean energy works best when nature is treated as part of the design, not an obstacle to remove.