Floating solar panels could supply a large proportion of the electricity demand in several countries, and the entire demand of some nations, new research has shown.

The study by Bangor and Lancaster universities and the UK Centre for Ecology & Hydrology (UKCEH), calculated the daily electrical output for floating photovoltaics (FPV) on nearly 68,000 lakes and reservoirs around the world, using available climate data for each location. 

The researchers looked at where the technology is most likely to be installed, identifying lakes or reservoirs that did not dry up, did not freeze for more than six months each year, were no more than 10km from a populated district and not in a protected area. They calculated output based on FPV covering 10% of their surface area, up to a maximum of 30 km2, as a level that is likely not to harm a lake’s ecosystem.

The study, funded by the Natural Environment Research Council, has been published in the journal Nature Water. It found five nations could meet their entire electricity needs from FPV - Papua New Guinea, Ethiopia, Rwanda, Benin and Kiribati. Others would come very close including Bolivia and Tonga who could meet 87% and 92%, respectively, of their electricity demand. 

Many countries, mainly from Africa, the Caribbean, South America and Central Asia, could meet between 40% and 70% of their annual electricity demand through FPV.  In Europe, Finland could meet 17% of its electricity demand from FPV and Denmark 7%.

There are currently very few FPV installations in the UK, with the largest being a 6.3 MW floating solar farm on the Queen Elizabeth II reservoir, near London. The study estimated that the UK could potentially produce 2.7 terawatt hours (TWh) each year from FPV or 1% of overall demand – currently around 300 TWh. This is enough electricity for around one million homes.

While output fluctuated depending on altitude, latitude and season, the potential annual electricity generation from FPV on the 68,000 lakes and reservoirs globally was 1302 TWh. 

FPV have advantages over land-based solar installations, freeing up land for other uses and keeping panels cooler, making them more efficient. They are likely to particularly help lower income countries with high levels of sunshine.

Initial evidence suggests that FPV may have some environmental benefits, including reducing water loss through evaporation, by sheltering the lake surface from the sun and wind, as well as reducing algal blooms by limiting light and preventing nutrient circulation. However, the researchers stress more research is needed.

Dr Steve Thackeray, a lake ecologist at UKCEH, provided insights on the ecological implications of the study findings for the new paper.

He explains: “This study provides an essential global perspective on the great potential for floating solar photovoltaics to meet a significant proportion of our energy demand, as part of a transition to renewable energy sources. 

“While being a key element of our transition towards clean energy, the installation of such technologies on water bodies could have ecological impacts.

"We advocate close collaboration among energy and environment researchers, engineers and manufacturers so that any potential impacts are factored in during the design of future deployments. This would enable us to both maximise the potential of these technologies and safeguard against impacts on water quality and biodiversity.”

The researchers say that, depending on a lake’s ecosystem, the percentage of water body covered by solar panels may need to be reduced in some situations, or could be higher in others.

You can find out more about UKCEH research into reservoir-based renewable energy solutions via our online brochure.

Paper information

Woolway et al. 2024. Decarbonisation potential of floating solar photovoltaics on lakes worldwide. Nature Water. DOI: 10.1038/s44221-024-00251-4. Open access.