Hybrid systems of floating solar panels and hydropower plants may hold the technical potential to produce a significant portion of the electricity generated annually across the globe.

That’s according to an analysis by researchers at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL).

The researchers estimate that adding floating solar panels to bodies of water that are already home to hydropower stations could produce as much as 7.6TW of potential power a year from the solar PV systems alone, or about 10,600?TWh of potential annual generation. Those figures exclude the amount generated from hydropower.

For comparison, global final electricity consumption was just over 22,300 terawatt-hours in 2018, the most recent year for which statistics are available, according to the International Energy Agency.

Floating photovoltaics (PV) remain a nascent technology in the United States, but their use has caught on overseas where space for ground-mounted systems is less available.

So far, only a small hybrid floating solar/hydropower system has been installed, and that is in Portugal.

NREL estimates 379,068 freshwater hydropower reservoirs across the planet could host combined floating PV sites with existing hydropower facilities, although additional siting data is needed prior to any implementation.

The article highlights the potential benefits of coupling floating PV with hydropower:

A hybrid system would reduce transmission costs by linking to a common substation. Additionally, the two technologies can balance each other.

The greatest potential for solar power is during dry seasons, while for hydropower rainy seasons present the best opportunity. Under one scenario, that means operators of a hybrid system could use pumped storage hydropower to store excess solar generation.

The new paper, Hybrid floating solar photovoltaics-hydropower systems: Benefits and global assessment of technical potential, has been published in the journal Renewable Energy. Lead author is Nathan Lee, a researcher with NREL’s Integrated Decision Support group. The article is co-authored by NREL colleagues Ursula Grunwald, Evan Rosenlieb, Heather Mirletz, Alexandra Aznar, Robert Spencer, and Sadie Cox.

Says Nathan Lee: “This is really optimistic. This does not represent what could be economically feasible or what the markets could actually support. Rather, it is an upper-bound estimate of feasible resources that considers waterbody constraints and generation system performance.”

Funding for the research came from NREL’s Laboratory Directed Research and Development Program.

NREL is the US Department of Energy’s primary national laboratory for renewable energy and energy efficiency research and development.