Fraunhofer ISE and RWE study explores the floating solar potential on Germany’s artificial lakes
The technical potential is much higher than the economically and practically exploitable potential
It would need the government to expand the limit of 15% water coverage area to 35%
The purely technical potential of floating solar PV systems on all artificial lakes with a minimum 1-hectare size in Germany can go up to 45 GW, provided the country allows for water coverage to be raised from 15% at present to 35%, according to a new study.
Conducted by the German energy group RWE and the Fraunhofer Institute for Solar Energy Systems ISE, it believes this technical potential is at a minimum 14 GW with 15% water coverage and 20 meters of edge strip.
“In the edge strips considered in the analysis, floating PV use is often not possible due to shading, vegetation, water depths that are too low and the like. That is why they were not taken into account in this conservative potential calculation,” explained Co-Author of the study Cassandra Mpofu.
Germany has 6,043 artificial lakes with a size of at least 1 hectare, representing more than 90,000 hectares of combined capacity. Most of these are located in Saxony and Baden-Württemberg. Around 70% of these are gravel pits. Fraunhofer said reservoirs, retention basins, dams and mining lakes were also studied.
Under the current permissible limit as laid down in the Renewable Energy Sources Act (EEG) and Water Resources Act, Germany allows a maximum of 15% of a body of water’s surface to be covered with solar systems. These also need to maintain a distance of at least 40 meters from the shore.
With these strict technical, economic and ecological restrictions, the country’s ‘economically and practically exploitable’ floating PV potential on artificial lakes stands at 1.8 GW floating PV capacity with south-facing modules. With east-west orientation, it can go up to 2.5 GW.
At present, Germany’s operational floating solar PV capacity is 21 MW, with another 62 MW in approval or under construction.
Part of a Federal Ministry for Economic Affairs and Climate Protection (BMWK) research project PV2FLOAT, the study follows a 2020 BayWa commissioned analysis by Fraunhofer ISE. Back then, the institute pegged 56 GW as the technical potential for floating PV on lignite opencast mines (see Study Explores Floating PV Potential In Germany).