Solar Panels on Reservoirs Complement Hydroelectric Power; Floatovoltaics Increase Energy Generated From the Sun by 10 Times

Solar panels have become increasingly popular because there is no question that the Sun is a good source of renewable energy. The question now is where to deploy solar panels on a large scale; some are installing them in empty spaces and reservoirs.

Floating Photovoltaic Systems: Solar Panels on Reservoir

A new study from an international team of researchers showed the benefits of floatovoltaics or floating solar panels on water reservoirs.

Based on their calculation, covering 30% of the surface of 115,000 reservoirs globally could generate 9,434 terawatt hours of power annually, which is twice the energy that the United States generates annually. That is enough to power 6,200 cities in 124 countries, WIRED reported.

J. Elliott Campbell, an environmental engineer at the University of California, Santa Cruz and coauthor of the paper, said the energy it could generate, 9,434-terawatt-hours-per-year potential, was ten times the current solar energy generated. Solar is growing, and the question is where to place those solar panels.

Floatovoltaics are like solar panels on land, but they are floating. Each one is a cluster or "island" of panels. They are built atop a buoyant mounting platform and anchored to the bottom of the water by cables.

The design is built to resist rust when exposed to rain. They can be likened to a rooftop or ground mount system, according to Chris Bartle, director of sales and marketing at Ciel & Terre USA, which deploys floatovoltaic projects worldwide.

Bartle said they used old technology from the marina world and applied it when they built a structure where an array of solar panels can be mounted.

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Benefits of Floatovoltaics

Aside from generating energy, floatovoltaics keep water cool, making them around 5% more effective than land-based ones, according to AZO Cleantech. Solar cells can overheat, but water cooling the floatovoltaics can harvest more energy from the Sun.

Multiple panel arrays shield the water surface from the Sun, reducing evaporation and retaining more volume of water, which in turn provides more water for hydropower and irrigation.

WIRED added that the panels could save enough water from supplying 300 million people annually. Also, another paper based on the same principle suggested that if California spanned 4,000 miles of its canal system with panels, it would save 63 billion gallons of water from evaporation each year and provide half the new clean energy capacity the state needs to reach its decarbonization goals.

Saving water is important because climate change speeds up drought. The water level at reservoirs has declined, and hydroelectric generation has started to dip.

Floatovoltaics also complement hydroelectric power that is already generated by a reservoir. According to Zhenzhong Zeng of China's Southern University of Science and Technology, a coauthor of the new paper, the two power sources balance each other.

Among the challenges of solar energy is its intermittency, and hydroelectric power, which tends to be controlled, can make up for the former's shortfall at night. Also, it can be combined with wind power, which is well-complemented with solar.

The study was published today in Nature Sustainability.