Floating solar or floating photovoltaics (FPV), sometimes called floatovoltaics, are solar panels mounted on a structure that floats on a body of water, typically a reservoir or a lake such as drinking water reservoirs, quarry lakes, irrigation canals or remediation and tailing ponds. A growing number of such systems exist in China, France, India, Japan, South Korea, the United Kingdom, Singapore, and the United States.
The systems have advantages over photovoltaics (PV) on land. Water surfaces may be less expensive than the cost of land, and there are fewer rules and regulations for structures built on bodies of water not used for recreation. Life cycle analysis indicates that foam-based FPV have some of the lowest energy payback times (1.3 years) and the lowest greenhouse gas emissions to energy ratio (11 kg CO2 eq/MWh) in crystalline silicon solar photovoltaic technologies reported.
Unlike many land-based solar plants, floating arrays can be unobtrusive because they are hidden from public view. They can achieve higher efficiencies than PV panels on land because water cools the panels. The panels can have a special coating to prevent rust or corrosion.
The market for this renewable energy technology has grown rapidly since 2016. The first 20 plants with capacities of a few dozen kWp were built between 2007 and 2013. Installed power grew from 3 GW in 2020, to 13 GW in 2022, surpassing a prediction of 10 GW by 2025. The World Bank estimated there are 6,600 large bodies of water suitable for floating solar, with a technical capacity of over 4,000 GW if 10% of their surfaces were covered with solar panels.
The costs for a floating system are about 10-20% higher than for ground-mounted systems.
American, Danish, French, Italian and Japanese nationals were the first to register patents for floating solar. In Italy the first registered patent regarding PV modules on water goes back to February 2008.
The first floating solar installation was in Aichi, Japan, in 2007, built by the National Institute of Advanced Industrial Science and Technology.
In May 2008, the Far Niente Winery in Oakville, California, installed 994 solar PV modules with a total capacity of 175 kW onto 130 pontoons and floating them on the winery’s irrigation pond. Several small-scale floating PV farms were built over the next seven years. The first megawatt-scale plant was commissioned in July 2013 at Okegawa, Japan.
In 2016, Kyocera developed what was then the world’s largest, a 13.4 MW farm on the reservoir above Yamakura Dam in Chiba Prefecture using 50,000 solar panels.The Huainan plant, inaugurated in May 2017 in China, occupies more than 800000 m2 on a former quarry lake, capable of producing up to 40 MW.
Salt-water resistant floating farms are also being constructed for ocean use.
Floating solar panels are rising in popularity, in particular in countries where the land occupation and environmental impact legislations are hindering the rise of renewable power generation capabilities.
Global installed capacity passed 1 GW in 2018 and reached 13 GW in 2022, mostly in Asia. One project developer, Baywa r.e., reported another 28 GW of planned projects.