Long popular in Asia, floating solar is also gaining popularity in the United States

When Joe Seaman-Graves, the urban planner of the working class town of Cohoes, New York, Googled the term “floating solar energy,” he didn’t even know it was a thing.

However, he knew his small town needed an affordable way to get electricity and didn’t have extra land. However, looking at the map, one feature stood out.

“We have this 14-acre water reservoir,” he said.

Seaman-Graves soon found that the reservoir could accommodate enough solar panels to power all city buildings and streetlights, saving the city more than $500,000 each year. He had stumbled upon a form of clean energy that was on the rise.

After rapid growth in Asia, floating solar panel systems are starting to boom in the United States. They are attractive not only because of their clean electricity and zero land use, but also because they save water by preventing evaporation.

A study published in March in the journal Nature Sustainability found that thousands of cities — more than 6,000 in 124 countries — could generate an amount equal to their entire electricity needs with floating solar arrays, making it a serious climate solution. By doing so, they could save about enough water each year to fill 40 million Olympic-size swimming pools.

Zhenzhong Zeng, a collaborator on this study and an associate professor at Southern University of Science and Technology in Shenzhen, China, said that in the United States, counties in Florida, Nevada and California have the potential to generate more electricity than they use. Of course, they would need an energy mix to provide electricity throughout the day, Zeng said.

The concept of floating solar power is simple: attach panels to rafts so they float on the water rather than blocking land that could be used for farming or building. The panels are sealed and act as a lid, reducing evaporation to near-zero, benefiting regions like California that experience frequent droughts. The water also keeps the panels cool, allowing them to generate more electricity than their land-mounted counterparts, which lose efficiency when they get too hot.

“We hear from our installers that they like it because it’s different,” said Chris Bartle, director of sales and marketing for floating solar company Ciel & Terre, which has built 270 projects in 30 countries. “You can go on water and not on a roof. We joke that you need life jackets instead of ladders,” he said.

Bartle’s company has launched 28 floating solar projects in the US

Limited land may have prompted some countries in Asia, such as Japan and Malaysia, to expand floating solar, while other countries have simply taken advantage of the sharp drop in solar energy prices that has dramatically changed the economic landscape for global solar energy adoption.

A report by London-based Fairfield Market Research says the region currently generates 73% of floating solar sales and is “the spearhead of the global landscape,” but predicts policy stimulus in North America and Europe will spur significant growth become.

One of the largest floating solar farms in the US is the 4.8 MW project built by Ciel & Terre in Healdsburg, California.

“It’s funny, I don’t think many people in Healdsburg know about it,” said David Hargreaves, a local real estate agent and YouTuber who lives nearby. People might not know that solar panels can be placed on water, so they don’t pay attention, he said.

The largest system in the world to date is the Dezhou Dingzhuang floating solar park with 320 MW in Shandong, China. By comparison, North America’s largest power plant is just a fraction of that — 8.9 MW at the Canoe Brook water treatment plant in Millburn, NJ, owned by New Jersey Resources Clean Energy Ventures, which operates commercial and residential utility-scale solar plants nationwide in the Northeast.

“We’re excited to see it gaining momentum in the US,” said Robert Pohlman, vice president of NJRCEV.

However, higher upfront costs remain an obstacle. Bartle estimates that floating solar systems cost 10-15% more initially than land-based solar systems, but owners save money in the long run. Deeper water can increase installation costs, and the technology cannot be used on fast-moving water, in the open sea, or on shores with large waves.

Engineers work on other challenges. If the solar panels cover too much of the water surface, the dissolved oxygen level could change and the water temperature could drop, which could harm aquatic life. Researchers are investigating whether the electromagnetic fields generated by cables could negatively affect aquatic ecosystems. However, there is no evidence for this yet.

Duke Energy, the major US utility with approximately 50,000 MW of power capacity, aims to achieve net-zero carbon emissions in its power generation by 2050. The company has just launched a small floating solar pilot project of just under 1 MW in Bartow, Florida.

“The nicest part of my job is getting out of here,” said Tommy Oneal, environmental specialist at Duke Energy, as he pointed to new panels floating on the cooling pond of an adjacent gas-fired power plant.

“I see eagles, alligators and all kinds of cool stuff… It’s fun, these themes make my job different every day. When I went to college, I never thought I would ever study alligator issues,” Oneal said.

In Cohoes, officials are preparing to install their project later this year, which is estimated to have a final cost of $6.5 million. The federal government bears almost half of this through a federal grant for housing construction and urban development. Another $750,000 will be paid by the utility National Grid. The city is also considering New York’s solar incentives and the Inflation Reduction Act.

To the best of his knowledge, Seaman-Graves said, it is the first community-owned floating solar project in the country.

“We’re an environmental justice community and we see a huge opportunity for low- to middle-income cities to replicate what we’re doing,” he said.