The floating photovoltaics systems (FPV) are a type of system installed on the surface of water reservoirs. The use of FPV systems makes it possible to avoid the problems associated with the cost of renting land, which is becoming more expensive and less available. Installing PV systems on water also makes it possible to increase the efficiency of the installation by improving the cooling of the panels due to lower heating of the water surface in relation to the ground surface and reducing dust deposition. Installing floating systems also saves land from an agricultural and urban planning perspective. The negative aspect of installing such systems can be the exclusion of a part of the water body from the fishing industry, strong wave action in case of marine and ocean installations, as well as the problem of energy collection [1].
The floating photovoltaic systems are installed by using different mounting solutions. Photovoltaic panels are installed above water on pontoons made of plastic such as high density polyethylene (HDPE). The installation is anchored using cement weights placed at the bottom of the water body or set on its shore. A PV installation anchored to the bottom of the reservoir is shown in Fig. 1.

Figure 1: Floating photovoltaic farm installed over water on 500 kWp pontoons by NRG Island. Photo used with permission from NRG Island.

Piemme srls, Floating Photovoltaic Plant NRG ISLAND, 23.06.2020 (accessed 23.03.2020). Available on YouTube: https://youtu.be/joUC8DJwI7c.

The floating installations are also made by using a partially submerged system in which the panels are partially submerged in water, which allows the efficiency of the panels to increase due to their cooling by the water [2]. Semi-submerged systems use panels on flexible substrates that float directly on the water. The panels float by using floats placed at the edge of the panels and anchored with ropes. Such a concept of installation of PV systems was first presented by MIRACO, which installed a system with a total area of 75 \( m^{2} \) and 8 kW in Comino, Malta.
The first floating photovoltaic system was fabricated for research purposes in 2007 in Aichi, Japan with a capacity of 20 kW. The panels were placed on foam polystyrene panels and raised at an angle of \( 1.3_{}^{o}\textrm{} \) toward the south [1]. The first commercial PV system floating on surface water was a 175 kW installation. The installation was made by SPG Solar in 2008 at Far Niente Winery.
The first floating PV power plant at sea was a farm made by Ocean of Energy. This farm was installed in the Dutch North Sea in late November 2019 ( Fig. 2 ). The power of the system was initially 8.5 kW and consisted of 28 panels, and on January 20, 2020 it was increased to 17.5 kW by installing 28 more panels. The farm has so far survived several storms, including Orkan "Sabina", during which it remained intact despite wind speeds exceeding 30 \( \frac{m}{s} \), as well as 5-meter waves.

Figure 2: Oceans of Energy's first photovoltaic power plant in the Dutch North Sea. Photo used with permission from Oceans of Energy.

One of the largest floating photovoltaic installations was built on a lake in Anhui, China. It has more than 165 000 photovoltaic panels and produces 40 MWp of electricity per year [3]. A floating installation in Anhui is shown in this video "World's largest floating solar farm in E China".

New China TV, World's largest floating solar farm in E China, 21.06.2017 (accessed 14.12.2020). Available on YouTube: https://youtu.be/qKpYH5SYUeo.