Space utilisation rethoughtThe next generation of photovoltaics 

80 percent share of renewable energies in Germany’s electricity mix by 2030 - this is how the German Federal Government’s goal is laid down in the Renewable Energies Act (EEG) 2023. By 2025, the share of renewable energies in electricity consumption was already around 55 percent - a significant improvement compared to previous years. But there is still a long way to go before reaching the 80% target.

Expansion is progressing, but not fast enough everywhere: With regard to the expansion of photovoltaics, Germany is currently slightly above the EEG target path, but the expansion of onshore wind power has been behind targets for years - despite recent accelerated approval figures. The German Federal Environment Agency therefore states: In order to reach the 80 percent target, expansion must be further accelerated.¹

An intensification of the existing conflicts in terms of land use is therefore inevitable. Where will all the new areas be – especially those for the expansion of photovoltaics (PV)? The Federal Ministry for Economic Affairs and Climate Action has said that all suitable roof areas should be used, new commercial buildings must be equipped with solar systems and new private buildings must also be better equipped than before. But is that enough?

A complementary alternative would be to use water catchment areas and agricultural land – without denying the crops the sunlight they also need. Innovative approaches to combining the cultivation of foodstuffs and electricity production by PV on one and the same area are, in fact, available. We are talking about “Agri-PV”, plus “Floating PV” for water areas. What is the current state of development? 

Rethinking agriculture – with agricultural PV for more efficient land use

Agricultural PV refers to the double use of agricultural land for the simultaneous generation of electricity by photovoltaic systems installed on these areas.

The concept is largely driven by the Fraunhofer Institute for Solar Energy Systems ISE. It therefore offers potential because it is flexible and can be specifically adapted to the respective agricultural use. Regardless of the size of the cultivated plant, whether it is fruit, cereals or special crops, whether in Germany, the Mediterranean or Africa: the systems can be used anywhere and, depending on the design, can even increase the efficiency of cultivation.  

As it is in the field, so it is on the water

The design of floating PVs is comparable. It involves using unused areas on artificial lakes to install floating PV systems. 

These include flooded pits from the open-cast mine or reservoirs. Although these areas are not used twice, valuable synergy effects still arise. The water cools the solar modules and the modules reduce the sun’s incidence on the water, so that less ecosystem polluting algae forms. It is also possible to couple the floating PV systems with hydropower or wind power in order to use the surrounding areas even more efficiently, counteract weather fluctuations and optimise maintenance processes.  

In contrast to agri-PV, floating PV (photovoltaics) is still a relatively young but rapidly growing usage concept on water surfaces. The total installed power increased from 10 megawatts in 2014 to over 7.7 gigawatts in 2023.³ This significantly exceeded the 2.6 GWp determined by the Fraunhofer Institute in 2021.

The expansion potential for Germany is considerable, albeit lower than originally estimated: A recent analysis by RWE and the Fraunhofer ISE showed that the economically practical potential at 1.8 gigawatt peak (south orientation) and 2.5 gigawatt peak (east-west orientation) in Germany has great potential for floating photovoltaics - Fraunhofer ISE. The purely technical potential is significantly greater with at least 14 gigawatt peak at 15 percent water coverage and would even increase to up to 45 gigawatt peak at 35 percent coverage.⁵

In Germany, there are more than 6,000 artificial lakes with an area of at least one hectare, which together cover over 90,000 hectares. Photovoltaic systems with a peak output of just over 44 megawatts are currently being operated in German waters, and a further 79 megawatts are currently being approved or constructed.⁶

Outlook for a “green” future

The use of innovative concepts such as agri-PV and floating PV should become more widespread through the incentives the German Federal Government will soon enshrine in law, if not before. The multiple benefits enable farmers to further increase the economic efficiency of operations or investments for energy suppliers with decommissioned lignite mines and institutional investors, while contributing to a “greener” electricity mix. The fact that innovative ideas become reality and spread exponentially is not only gratifying but a welcome development for the energy production of tomorrow.