In 2026, EDP APAC deployed 13,312 solar panels on more than 30,000 pontoons in Singapore’s Strait of Johor. Today, marine growth has increased floater mass by nearly 43%, putting buoyancy and electrical connectors at risk

Singapore built a solar farm on seawater because there simply was not enough land to keep expanding solar power on the island. Off Woodlands, along the Straits of Johor, more than 13,000 solar panels float across the coastal waters, forming a 5 MWp installation designed to cope with waves, currents, wind and seawater. The engineering challenge was obvious: keep a huge floating structure stable in a moving marine environment. But another problem came from a much smaller source. Barnacles began attaching themselves to the floating infrastructure, turning marine biology into an unexpected engineering concern.

Why Singapore had to put solar panels on the sea

Singapore has a basic problem that many larger countries do not face: there is very little spare land. Its dense urban development leaves limited room for conventional ground-mounted solar farms, while rooftops can only provide part of the space needed to expand renewable generation. That constraint has pushed the country toward less conventional locations, including reservoirs and coastal waters, where large surfaces can be used without competing directly with housing, industry or transport.

The Woodlands project was developed by Sunseap, now part of EDP APAC, as a demonstration of what offshore floating photovoltaic technology could achieve in a land-scarce city. Completed in 2021, the system contains 13,312 photovoltaic panels, 40 inverters and more than 30,000 floating units across roughly five hectares. Its peak capacity is 5 MWp, with estimated annual production of about six million kilowatt-hours.

The real engineering problem was not simply the waves

Putting solar panels on seawater is fundamentally different from installing them on a roof or an inland reservoir. The platform is constantly exposed to movement generated by waves, currents and wind. Passing vessels can also create additional disturbances in coastal waters. Instead of forcing the entire structure to remain rigid, engineers designed a compliant floating system that can move with the water while remaining connected and controlled.

A constant-tension mooring system helps hold the floating array in position while allowing controlled movement. The system was engineered for marine conditions rather than the relatively sheltered environment of a freshwater reservoir. Project documentation says the floaters and mooring arrangement were designed to withstand sea waves, while corrosion from prolonged exposure to saltwater also had to be considered from the beginning.

That distinction matters because seawater creates several problems simultaneously. Salt can accelerate corrosion in exposed equipment, waves impose repeated mechanical loads, and currents can place stress on connections and mooring lines. The array also has to operate safely around maritime traffic and remain accessible for maintenance. The Woodlands project therefore became less like a conventional solar farm and more like a small floating marine structure carrying an electrical power plant.

Then the ocean started building on the Solar farm

Barnacles create a completely different category of problem because they are not an external force acting on the platform. They become part of the platform itself. Marine organisms such as barnacles and mussels can settle on submerged surfaces, producing what engineers call biofouling. Once established, these organisms can grow into dense layers on floats, cables and other underwater components. The Woodlands project identified barnacles as one of the challenges associated with operating a solar farm in the open sea.

The biology behind it is straightforward but surprisingly consequential. Barnacle larvae spend part of their life cycle drifting through seawater. When conditions are suitable, they attach to a hard surface and transform into permanently fixed adults. A floating solar installation provides thousands of square metres of artificial habitat that would not otherwise exist in exactly that configuration. Its floats, supports and submerged components effectively become new surfaces available for marine organisms to colonize.

Why Barnacles can become an engineering problem

A single barnacle is hardly a threat to a power plant. The problem comes from accumulation. As marine growth spreads across submerged components, it adds mass to structures designed around specific buoyancy and loading assumptions. Floating photovoltaic systems depend on buoyant elements to keep the panels and associated equipment at the required position above the water. Additional biological growth can therefore change the loads acting on those components.

Biofouling can also increase drag. A clean submerged surface moves through water differently from one covered in rough biological growth. As currents act on the fouled structure, resistance can increase and place additional demands on moorings and connections. That does not mean barnacles are capable of suddenly sinking the entire installation, but sustained growth can become a maintenance and structural-management issue that engineers have to account for.

There is another practical complication. Marine growth does not necessarily appear uniformly. Some surfaces may become heavily colonized while others remain comparatively clean, creating uneven loading and making inspection more important. In a large installation containing tens of thousands of floating elements, checking submerged components is also considerably harder than inspecting a conventional land-based solar array.

Singapore’s warm waters make biofouling especially relevant

The Straits of Johor is not an empty stretch of ocean. It is a productive tropical marine environment, and the same biological richness that makes the water ecologically active can make floating infrastructure attractive to organisms looking for surfaces on which to settle. This is one reason offshore solar cannot simply copy the designs used on inland reservoirs.

Researchers studying the Woodlands installation have treated coastal conditions as a separate engineering problem. A published study of the project describes the need to account for coastal wave conditions, including disturbances produced by passing vessels, and explains how the floating system was verified through numerical modelling and full-scale experimental testing. The researchers describe the platform as a modular system using high-density polyethylene floats designed to follow wave motion.

The lesson is broader than one solar farm. Floating photovoltaic technology has often been associated with reservoirs, where water movement and biological conditions can be quite different from those found in coastal environments. Moving the technology into seawater opens much larger areas for solar generation, but it also introduces corrosion, marine growth, waves, currents and navigation issues that cannot be treated as minor variations.

The Panels are only part of the system

It is easy to look at photographs of floating solar farms and think the main challenge is simply keeping the panels above water. In reality, the photovoltaic modules are only one part of a much larger system. The Woodlands installation includes more than 30,000 floats, electrical equipment, mooring infrastructure and a subsea connection that carries generated electricity toward Singapore's grid.

That complexity explains why something as ordinary as marine growth matters. A solar panel can continue producing electricity while organisms colonize a float several metres away, but the entire system depends on the supporting infrastructure remaining mechanically sound. Maintenance therefore has to consider the biological environment as carefully as it considers weather and electrical performance.

The project was ultimately designed around that reality rather than treating the sea as an empty space. EDP APAC says the floating system was completed in March 2021 and describes it as one of the world's largest floating solar farms on seawater. The company lists an estimated annual generation of about 6,000 MWh and says the installation can provide enough electricity for up to 1,100 four-room public housing flats.

What Barnacles reveal about the future of offshore solar

The unexpected barnacle problem points to a larger truth about renewable energy. Moving solar panels from land to water does not remove environmental constraints. It changes them. On land, developers worry about available acreage, land prices, vegetation and competing uses. At sea, the engineering checklist expands to include waves, corrosion, currents, marine traffic and living organisms.

That makes offshore floating solar an unusually interesting intersection of engineering and biology. The structure is built by humans, but once it enters the water, nature immediately begins interacting with it. Barnacles do not recognize a photovoltaic array as infrastructure. To them, it is simply another hard surface in the sea.

Singapore's experiment therefore offers a useful warning for the next generation of floating solar projects. Designing for waves is essential, but it is not enough. A successful marine solar farm has to account for the physical ocean and the biological ocean at the same time. The waves may move the panels, but the barnacles slowly change the structure itself. And in the long run, that quiet biological process can be just as important to the engineering as the force of the water.