What Are Floating Solar Panels?  | Built In

Nov 07, 2024

Floating solar panels, also known as floating photovoltaics or floatovoltaics, are solar panels installed on structures that float on bodies of water. They convert sunlight into clean energy from raft-like structures on top of lakes, quarries, dams and reservoirs.

With more than 300 floating solar projects worldwide, interest in this new spin on an old technology is growing.

Floating solar panels are photovoltaic power systems that are installed on a body of water, such as quarry lakes, reservoirs and ponds, where they convert sunlight into energy.

By installing solar panels on water rather than land, we can better conserve land resources, reduce water evaporation and improve panel efficiency — by taking advantage of the cooling effect of water. Water surfaces are also less costly than land, and there are often fewer regulations for structures built on non-recreational bodies of water.

Like conventional solar panel systems, floating solar panel systems consist of solar arrays — except these ones are mounted on buoyant, water-resistant platforms typically made from high-density polyethylene or other plastics. This allows the systems to stay afloat while capturing sunlight to generate electricity. Floating solar panels are often installed on man-made bodies of water to avoid damage caused by waves, tides and saltwater corrosion.

From the water’s surface, the photovoltaic cells on each panel absorb light particles, then transfer their energy through semiconductor materials. This process causes electrons to move, creating a flow of direct current electricity. That electricity is then converted into alternating current using an inverter, making it available for use in homes, businesses and the power grid.

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Below lists the five largest floating solar panel projects — in terms of operational capacity — to date.

Located in China’s Shandong Province, this 320 megawatt floating solar farm is currently the largest in the world. It generates 550,000 kilowatts of electricity annually, offsetting 217,700 tons of carbon dioxide emissions every year. It’s built on top of an artificial lake that formed over a flooded coal mine.

Three Gorges New Energy’s floating solar park is a 150 megawatt floating solar project spread over 790 acres. Built on top of several collapsed coal mines that were abandoned and flooded, the project is part of a major hydroelectric power station in China, known as the Three Gorges Project. Every year it generates about 150,000 megawatts of electricity, which is enough to power 94,000 households.

Developed by the state-owned organization China Energy Conservation and Environmental Protection Group, this 70-megawatt floating solar farm features more than 194,000 panels. Located in the Anhui Province of China, it generates about 77,600 megawatts of electricity per year — enough to power about 21,000 households.

The Sembcorp Tengeh floating solar farm is a 60 megawatt installation that floats roughly 122,000 PV modules over the Tengeh Reservoir in Singapore. Annually, it generates 77,300 megawatts of electricity, offsetting 32,000 tons of carbon emissions and powering about 16,000 four-bedroom flats per year. This project, which spans the area of 45 football fields, works within the land limitations in densely populated areas like Singapore, while also advancing the country toward its goal to quadruple solar energy production by 2025.

With a capacity of 45 megawatts, the Sirindhorn Dam floating solar farm in Thailand is part of a hybrid system that merges solar and hydro power. Made with double glass solar panels and a high density polyethylene mooring system, the project cuts carbon emissions by 47,000 tons per year, while also reducing the dam’s water evaporation levels by around 460,000 cubic meters annually.

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Floating solar farms and parks introduce a fresh take on renewable energy generation, harnessing untapped water surfaces and promising vast potential.

Thanks to the cooling effect of water, floatovoltaics can be up to 15 percent more efficient than their land or roof-based counterparts. In fact, if we were to cover just 10 percent of the world’s available hydropower reservoirs with floating solar systems, it would generate about 4,000 gigawatts worth of electricity — comparable to the current output of fossil fuels plants.

Floating solar panel farms occupy water surfaces instead of land. This makes them ideal for high-density regions with limited land availability, and also where land is prioritized for agriculture, urbanization or conservation.

Floating solar panels shade the water below, reducing evaporation rates. This feature is particularly useful in dry, arid climates and a useful side effect for those overlaying irrigation reservoirs. Floating solar installations may even be considered a way to protect desiccating natural lakes and other bodies of water that tend to dry up. By blocking the sunlight from reaching the water surface, these systems also limit algae growth, which can help prevent algal blooms and maintain water quality.

These on-water systems are retrofitted into pre-existing man-made structures and actually repurpose previously exploited land, such as brownfields and flooded mine pits, that might otherwise remain unusable. This not only maximizes the use of already-there infrastructure, but also reduces any pressure to further develop land for renewable energy production, and in some cases, actually help preserve and rehabilitate natural ecosystems by preventing further degradation.

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While floating solar panel parks and farms come with a number of benefits, they also present some drawbacks compared to conventional methods.

Building solar panels on water requires specialized materials and anchoring systems, making it more costly to install and maintain than land-based installations. One study, conducted by the National Renewable Energy Laboratory, found that floating solar panel systems cost about 25 percent more than conventional ground-mounted installations. These systems have much higher structural costs related to the floats and anchoring systems that must be specialized to each site.

Despite the positive impact of reduced water evaporation and decreased algae growth, large-scale floating solar farms can also negatively impact aquatic ecosystems. By reducing sunlight penetration of an area, these systems may interfere with photosynthesis for underwater fauna and flora and alter habitats for marine life. Electrical components could also create electrical fields unnatural to the site, while the slow process of corrosion and degradation could release chemicals and microplastics into the water over time. Still, there are no environmental studies performed on floating solar projects yet, and this information is inferred from similar projects.

Floating solar farms require specific types of water bodies, like calm reservoirs or quarry lakes. They’re unsuitable for areas with turbulent waves, currents or tides or for those specifically designated for recreational or commercial purposes. At this time, floating solar panels are really only an option for large enterprises and governments rather than smaller entities, including individual homeowners, unlike rooftop panels or community solar farms.

Yes; And they are about 15 percent more efficient than conventional methods and modules.

Floating solar panels have a higher upfront cost than land-based systems and can only be built on calm, low-salt water bodies. Despite some of the positive environmental impact they have, they introduce electrical fields to a natural space and block sunlight to the fauna and flora below.

The National Renewable Energy Laboratory estimated that floating solar panel systems cost about 25 percent more than their land-based counterparts.