Floating PV has a major effect on water evaporation, and this was first demonstrated in a study of a PV system in a reservoir in Brazil.

Among the myriad benefits of floating PV systems, perhaps the most important is that they decrease evaporation levels in reservoirs, thanks to the shade created by the panels on the surface. This is a huge environmental benefit, especially in warmer, drought-stricken regions.

In the recent study by two universities, Ponta Grossa in Brazil and Louisiana-Lafayette in the United States, the effects of floating PV systems on water evaporation indices were calculated, examining a 130 kW floating PV system in the Passaúna reservoir in southeastern Brazil, about 8.5 square kilometers in size, as a case study. It is a plant that occupies an area of 1,265 square meters and has 395 PV modules of 330 W maximum power. To quantify the evaporation rate, the researchers used various meteorological data such as temperature, humidity, wind speed and solar radiation in their models.

The research is titled, “Effects of a Floating Photovoltaic System on the Water Evaporation Rate in the Passaúna Reservoir, Brazil,” and was published in the scientific journal Energies. The tests showed that the current photovoltaic system is capable of limiting water evaporation by 60 percent in the area of the reservoir covered by the modules.

Simulations were also carried out with larger PV systems of 1, 2.5 and 5 MW. It was seen that a 5 MW floating PV installation, can produce a decrease in evaporation equal to the volume of water for the average annual consumption of nearly 200 people. By covering the entire Passaúna Basin with floating PV modules, the lower evaporation could save enough water for the annual needs of more than 35 thousand people.

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