© Federal Ministry for Economic Affairs and Energy
What exactly is floating PV?
This is what it’s all about: floating PV installations are solar panels floating on waterbodies and anchored to the bottom or the side of the lake.
The summer sun is shining on Lusatia. In the lake which is the remains of the old gravel pit at Lohsa, some of the fish are seeking shade in the midday heat – and finding it under floating photovoltaic modules which convert solar energy into electricity and transport it to the lakeside. And the fish aren’t the only ones to benefit: the shade means that less water evaporates, and this is good for the lake.
There aren’t many floating PV installations in Germany yet, but they offer great potential. In the PV2FLOAT project, researchers from Fraunhofer Institute for Solar Energy Systems ISE and from RWE have studied how much potential is offered by floating solar panels for the roll-out of solar power. Brandenburg University of Technology Cottbus-Senftenberg also analysed the ecological aspects relating to the water. The project was granted approximately €2 million in funding from the Energy Research Programme of the Federal Ministry for Economic Affairs and Energy.
New guidelines pool recommendations for floating PV
The findings from the joint project can now be found in the guidelines entitled “Floating PV: sustainable energy generation on water” (in German only). They provide practical recommendations and information about the potential of floating PV, the latest technologies, and the legal framework. The guidelines also contain hints about planning and operating floating PV, and analyse their sustainability potential.
Floating PV installation on a lake in an old gravel pit near Ulm. © Fraunhofer ISE
Germany has more than 6,000 man-made lakes of a hectare or more in size, amounting to more than 90,000 hectares of water surface. According to the Core Energy Market Data Register, at present these are home to floating PV installations with peak capacity of approx. 44 megawatts; further projects with another 79 megawatts are in the approval process or are under construction.
Floating PV does not need any extra land surface, and so it doesn’t compete with other uses. It can be installed on lakes, calm bays, flooded open-cast mines and gravel pits. The modules are placed on floats which are anchored to the bottom or the side. The cooling effect of the evaporation cools the modules and boosts electricity production. The modules are connected to the grid on land, but the assembly and maintenance work is more complex than it is for solar panels on land.
Many artificial lakes are suitable for floating PV installations
The research project studied the types of man-made waterbodies which are suitable for floating PV, on the basis of strict technical, commercial and environmental criteria. In Germany, a maximum of 15% of the water surface may be covered, at a minimum distance of 40 metres from the bank.
More than two thirds of the analysed lakes were gravel pits, most of them located in Saxony and Baden-Württemberg; the study also looked a dammed reservoirs, retention basins, and lakes in former open-cast mines. Newly emerging waterbodies, e.g. in Lusatia or the Central Rhineland Lignite District, were not included, but will offer further potential in future.
The researchers see great commercially viable potential for 1.8 to 2.5 gigawatts of installed PV capacity on artificial lakes in Germany, depending on the orientation of the modules. One current practical example is the world’s first vertical floating PV installation, which came on stream on a former gravel pit in Starnberg in October 2025. As it uses less space, this technology could also be useful for smaller bodies of water.