Thousands of cities could be powered entirely by floating solar panels

Floating solar arrays have the potential to not only generate power for entire communities, but also to conserve a significant amount of water.

Recent research suggests that solar panels floating on water reservoirs could enable thousands of cities around the world to generate their entire electricity demand using locally sourced renewable energy, while also conserving water. Floatovoltaics work similarly to land-based solar arrays but are mounted on rafts on water. Despite their potential, this emerging technology has not yet been widely deployed, and in 2020, only generated less than 1% of the electricity produced by land-based solar farms.

However, a new study published in the journal Nature Sustainability indicates that 6,256 cities across 124 countries could theoretically meet all their electricity requirements by covering around 30% of the surface of nearby water reservoirs with floatovoltaics. The study analysed 114,555 reservoirs across the world using multiple databases, and then modelled potential power generation based on realistic climate data.

The researchers also estimated that these floating solar panels would conserve about as much water as 300 million people use annually, which would be incredibly useful in mitigating droughts exacerbated by climate change. Floating solar panels have a cooling effect on solar cells, which can help to keep them from overheating during heatwaves, and they could be deployed in tandem with hydroelectric dams to boost power generation during hot summer days. Additionally, they avoid the problem of competition for space with other land uses such as agriculture or habitat conservation that large land-based solar farms might encounter.

However, developers will still need to carefully assess the potential negative effects of each reservoir, since covering too much of the surface with solar panels could result in less oxygen in the water, which could harm fish. The study found that smaller populations of less than 50,000 people tended to be located in areas with the most potential for floatovoltaics, with just 15% of the cities studied with populations bigger than 1 million people being able to generate their entire electricity demand purely with floating solar farms. The United States has the most suitable reservoirs, followed by China and Brazil, and some floating solar projects have already been deployed in Asia and the US.