Distributed Energy Resources

NREL: Floating solar could provide 10 percent of U.S. electricity

Solar photovoltaic panels floating on man-made reservoirs in the United States could produce about 10 percent of the country’s electricity, according to researchers at the Energy Department’s National Renewable Energy Laboratory.

The emerging technology provides various benefits and makes sense in areas where land is costly, the researchers said last month in a paper published in Environmental Science & Technology.

The first-ever floating PV system — called a floatovoltaic — was installed a decade ago on an irrigation pond in Napa Valley, California, according to NREL.

There were seven floatovoltaic systems in the United States as of December 2017. There about 100 floating PV systems worldwide, with Japan emerging as a leader in the technology, according to NREL.

Worldwide, there are about 1,100 megawatts of installed floating PV capacity, up from 10 MW at the start of 2015, according to an October report from the World Bank and the Solar Energy Research Institute of Singapore. The World Bank estimates the global potential for floating PV at 400,000 MW.

“In the United States, it’s been a niche application; where in other places, it’s really been a necessity,” said Jordan Macknick, an NREL researcher and principal investigator in a project that led to the paper, Floating Photovoltaic Systems: Assessing the Technical Potential of Photovoltaic Systems on Man-Made Water Bodies in the Continental United States.

The NREL researchers said they used conservative assumptions in the first-ever research looking at the potential for floatovoltaics in the United States.

Floatovoltaics can help lower evaporation and algae growth in reservoirs, according to an abstract of the paper. At the same time, being based on water can lower PV operating temperatures from water’s cooling effects and potentially cut the costs of solar energy generation, the abstract said.

Also, setting up floating PV near hydroelectric facilities leads to higher energy output and cost savings by the use of existing transmission infrastructure, the NREL researchers found.

There are about 24 ,400 man-made water bodies, representing about a quarter of all man-made reservoirs and 12 percent of their area in the lower 48 states, that are suitable for floatovoltaics, according to NREL.

Floating PV systems covering about a quarter of the identified suitable water bodies could produce nearly 10 percent of current national electric generation while freeing up 2.1 million hectares of land for other uses, NREL said.

“Many of these eligible bodies of water are in water-stressed areas with high land acquisition costs and high electricity prices, suggesting multiple benefits of FPV technologies,” NREL said.

NREL expects floatovoltaics will take off in the United States, especially in areas that are land-constrained and where there is conflict over solar facilities encroaching on farmland, Macknick said.

NREL’s team also found that operating floating PV alongside hydroelectric facilities yields increased energy output and cost savings because of existing transmission infrastructure.

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Public power and floating solar

Florida public power utility Orlando Utilities Commission in 2017 installed a floating solar array on a pond near its operations center in southwest Orlando, Fla.

In late 2017, OUC dedicated a 13-megawatt solar facility on the site of a former landfill that was once designated for the construction of a future coal plant. The utility also unveiled plans to construct floating solar arrays at the site.

Meanwhile, the Braintree Electric Light Department in Massachusetts is using a grant provided by the American Public Power Association’s Demonstration of Energy & Efficiency Developments (DEED) program to explore a solar power project that would float on a reservoir.