Can floating solar replicate its Asian success in America?

Floating solar is already booming in Asia where land is in short supply and prices are high. Now it’s making inroads in the U.S. as demand for renewable energy continues to soar. 

More reservoirs, stormwater basins, dams and even lakes are playing host to solar panels attached to rafts to form a floating layer strategically positioned on top of the water line.

New Jersey is currently home to the country’s biggest floating solar project, consisting of 16,510 panels generating 8.9MW of power. Over in Healdsburg, California, another floating solar farm produces 4.8 MW - enough to power more than 3,000 homes.

Elsewhere, the Department of Defense unveiled its first 1.1MW floating solar system at Camp Mackall, a Special Forces training site in North Carolina, in 2022. The panels will be the main power source for the site during outages from storms, as well as cutting energy costs by an estimated $100,000 a year. 

These projects show the growing potential of floating solar for U.S. water districts, producing clean energy without taking up land that could be used for agriculture or other development.

While they can’t match the output of many land-based projects – the largest U.S. project being the 875MW Edwards Sanborn in California’s Mojave Desert – floating solar has numerous plus points. As the water keeps panels cool, they’re able to generate more electricity than land-based panels which work less efficiently when they overheat.

There are cost benefits too. Compared to ground mount systems, floating solar also has reduced operation and maintenance costs, with no vegetation management activities required. Under a third-party owned system, developers can expect to pay less for lease or licensing costs. 

Water conservation is another advantage. Large scale rafts of floating panels can effectively seal the surface of the water to reduce evaporation. This is a particular benefit for drought-afflicted areas like California. In fact, a 2023 study published in the journal Nature found that covering 30% of the surface of the world’s 115,000 reservoirs with solar panels would not only meet the energy needs of more than 6,000 cities across 124 countries but it would save enough water to fill 40 million Olympic-sized swimming pools each year.

Finally, floating solar can be easier for local communities to accept. One of the big criticisms of land-based solar is that it’s an eyesore or taking up too much space. For water districts in particular, adding panels to reservoirs and retention ponds can be a more palatable alternative as the race to decarbonize picks up pace. 

Installing floating solar, however, isn’t as simple as putting panels on roofs. Not all bodies of water are suitable; fast moving water, open ocean or shorelines with big waves are all out. Cost is another issue. Floating solar projects are around 10% to 15% more expensive to set up than equivalent on land installations.

Deep water, too, poses additional challenges for how the rafts are ballasted while changing water levels and annual drainage to keep some water facilities in optimal condition can also impact performance.

The location of interconnection points where power is delivered to the electrical grid is another consideration. In less urban areas where a site host is unable to consume some or all the solar power, grid interconnection points can be a fair distance from the floating solar site, adding to project costs. Fortunately, for water districts with wastewater operations adjacent or close to the floating solar, the required infrastructure is usually already in place with interconnection point nearby.

Yet once solar farms are up and running, the energy produced can power owned real estate or even be sold to the grid to provide a regular income stream – depending on what’s allowed under local rules.