Floating solar panels: coming to a lake near you?

Recent research from Bangor and Lancaster Universities and the UK Centre for Ecology & Hydrology has explored the potential for deploying low-carbon floating solar arrays around the world.

Floating solar photovoltaics (FPVs), known colloquially as ‘floatovoltaics’, typically consist of an array of PV modules mounted upon a series of floats, which are moored into position on the surface of a water body.

The researchers calculated the daily electrical output for FPVs on nearly 68,000 lakes and reservoirs, using available climate data for each location.

Their calculations were based on the lakes and reservoirs that were most suited to the installation of floating solar technology. This meant that the bodies of water studied had to be no more than 10 km from a population centre and not located in a protected area. They also couldn’t dry up or freeze for more than six months each year.

Electrical output was calculated based on FPV covering 10% of each water body’s surface area, up to a maximum of 30 km².

“We still don’t know exactly how floating panels might affect the ecosystem within a natural lake, in different conditions and locations. But the potential gain in energy generation from FPV is clear, so we need to put that research in place so this technology can be safely adopted,” said lead author of the paper Dr Iestyn Woolway, from Bangor University.

“We chose 10% of a lake’s surface area as a likely safe level of deployment, but that might need to be reduced in some situations, or could be higher in others,” Woolway said.

While output fluctuated depending on altitude, latitude and season, the team estimated that the total annual power output would be 1302 terawatt hours (TWh) across all 67,893 water bodies — about four times the total annual electricity demand of the UK.

Benefits of floating solar farms

FPV have various advantages over land-based solar installations: they free up land for other uses and keep panels cooler, making them more efficient.

Potential environmental benefits include reducing water loss through evaporation by sheltering the lake surface from the sun and wind; and reducing algal blooms by limiting light and preventing nutrient circulation. However, the researchers cautioned that further research is needed on the overall environmental impact of FPV. They recommended that decisions to deploy FPV should consider the intended function of water bodies and how they are used, as well as the potential ecological impact.

When the figures were considered on a country by country basis, five nations could meet their entire electricity needs from FPV: Papua New Guinea, Ethiopia, Rwanda, Kiribati and Benin. Others, such as Bolivia and Tonga, would come very close, respectively meeting 87% and 92% of 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%.

Australia could meet just under 6% of its demand.

“Even with the criteria we set to create a realistic scenario for deployment of FPV, there are benefits across the board, mainly in lower income countries with high levels of sunshine, but also in Northern European countries as well,” Woolway said. “The criteria we chose were based on obvious exclusions, such as lakes in protected areas, but also on what might reduce the cost and risks of deployment.”

The study co-author, Professor Alona Armstrong of Lancaster University, added: “Our work shows there is much potential for FPV around the world. But deployments need to be strategic, considering the consequences for energy security, nature and society, as well as net zero.”

The team’s findings have been published in Nature Water.

Image credit: iStock.com/onuma Inthapong