What is the potential of floating solar panels?

  • According to a 2020 IEA report, solar power is the cheapest source of electricity in the world.
  • However, because it is land intensive, researchers have studied the potential of floating solar panels on bodies of water.
  • Their study suggests the idea has potential, but questions remain about its impact on wildlife and broader ecosystems.

Solar energy is the cheapest source of electricity in history today, according to a 2020 report by the International Energy Agency. But something is holding back this clean energy powerhouse: space. Unlike fossil fuel power plants, solar parks require a lot of space to generate enough electricity to keep up with demand. Most solar parks are made up of floor-mounted panels that take up land to grow food or create habitats for wildlife.

Although electricity and water do not normally mix, more and more floating solar parks are being used around the world. Floating solar panels on a lake or reservoir might sound like an accident waiting to happen. However, recent studies have shown that the technology produces more electricity compared to solar panels on the roof or on the ground. This is thanks to the cooling effect of the water under the panels, which can increase the efficiency of the power generation of these systems by up to 12.5%.

However, lakes and reservoirs are already very important to people and the planet. While these freshwater bodies cover less than 1% of the earth’s surface, they promote nearly 6% of its biodiversity and provide drinking water and irrigation plants that are vital to billions of people. Worryingly, climate change has increased surface temperatures of lakes around the world by an average of 0.34 ° C per decade since 1985. This encourages toxic algal blooms, lowers water levels, and prevents water from mixing between the different layers that naturally form in larger and deeper lakes and starving the depths of oxygen.

In a rush to decarbonize energy to slow global warming, could switching to floating solar parks only add to the world’s precious freshwater reserves? Notably, we found in recent research that carefully designed floating solar parks can actually reduce the threat of climate change to lakes and reservoirs.

Together with colleagues, I used a computer model to simulate how floating solar parks are likely to affect the water temperatures in the lake. Our simulations are based on Windermere, the largest lake in England and one of the best-studied lakes in the world.

Floating solar parks reduce how much wind and sunlight reach the surface of the lake and change many of the processes that take place in it. Since every floating solar farm has a different design, we ran simulations to see how lake temperatures changed with over 10,000 unique combinations of wind speed and solar radiation.

Floating solar panels can offset climate change by 10 years.

Image: Giles Exley

Our results suggest that changes in water temperatures caused by floating solar parks could be as big as climate change itself, only in the opposite direction.

A floating solar park that reduces wind speed and solar radiation over the entire lake by 10% could offset a decade of warming from climate change. Designs that shaded the lake more than protected it by reducing sunlight more than the wind had the greatest cooling effect. Evaporation decreased and the lake was mixed more frequently, providing oxygen to the deeper water.

These effects can vary depending on the depth, surface and location of a lake. However, ecological processes in lakes are most strongly influenced by wind speed and sunlight, which is what our simulations focused on.

While most of our simulations showed a win-win situation for lakes and floating solar parks, some indicated undesirable side effects. In a small number of simulations, we found that floating solar parks, which reduced wind speed at the lake surface more than sunlight did, could actually mimic or amplify the effects of climate change and increase the duration of the stratification of deeper lakes. Fortunately, we believe that careful planning of floating solar parks should reduce these risks.

The floating solar energy has increased more than a hundredfold in the last five years and reached an installed capacity of 2.6 gigawatts in 35 countries. If only 1% of the surface of all man-made water bodies (which are more accessible and typically less environmentally sensitive than natural lakes) were covered by floating solar panels, 400 gigawatts could be generated – enough power to power 44 billion LEDs Lightbulbs for a year.

Floating solar energy should make an important contribution to the decarbonization of the global energy supply. Our research suggests that, at random, this could have the added benefit of offsetting some of the damage to lakes caused by rising temperatures.

However, our simulations only covered the physical effects of floating solar energy, while other questions remain unsolved. How would floating solar parks interact with other lake uses such as sport or aquaculture? How would the wildlife that shares the lake fare? And which lakes are best suited for a floating solar park? The work of fully understanding the potential of this technology is only just beginning.

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