“Biodiversity photovoltaics” combines climate protection and sustainable agriculture

Electricity and biodiversity in the same field? Well-planned solar farms can make a valuable contribution to protecting biodiversity. Modern module mounting systems with special panels now make it possible to both grow crops and produce sustainable electricity on the same agricultural land.

Agri-photovoltaics, or abbreviated “Agri-PV”: “This refers to land that can be used both for agriculture and for solar energy generation,” explains Marcus Vagt, project manager of EnergyDecentral, DLG (German Agriultural Society). The ambitious German green energy targets can only be achieved if “we focus on the entire diversity of photovoltaic technologies and promote their expansion”, says Vagt. This view is shared by the Fraunhofer Institute for Solar Energy Systems ISE. The scientists from Freiburg, Germany, estimate the installable capacity in Germany for high-mounted agrivoltaics alone at around 1,700 gigawatts. In purely mathematical terms, around four percent of German agricultural land would be sufficient to cover the current electricity demand in Germany.

However, this potential varies according to the climatic conditions and also depends on the plants that are cultivated in such dual land use systems. “Most of the crops studied so far tolerate up to 15 percent shading without any significant loss of yield,” Schweiger emphasizes. Berries, fruit and fruiting vegetables, for example, benefit from shading, while the yields of forage crops, tubers and root crops as well as most cereals suffer minimally. Corn, field beans, soybeans and lupins, on the other hand, experience greater yield losses.

Added value in climate change

But this form of energy production can do even more. Pataczek: “When water is scarce, the plants benefit from less evaporation and therefore less water loss: the yield is higher than on the unshaded areas.” From the researchers' perspective, this stabilizing effect on crop yields makes agrivoltaics a promising option in areas prone to drought. “The technology not only helps to mitigate the effects of climate change in regions already classified as dry,” continues Andreas Schweiger. “It will be particularly important for regions that will face increasing water scarcity in the future.”

Marcus Vagt also sees great potential in southern Europe, where high levels of solar radiation are combined with dry areas: “Italy is one of the pioneers here and has earmarked over one billion euros for agri-PV in its reconstruction and resilience plan.” The agri-solar park near the Sicilian municipality of Mazara del Vallo in the province of Trapani is representative of this commitment. The first plant went into operation in May 2023 and covers more than 115 hectares. Local olives and almonds as well as medicinal herbs such as lavender and forage plants thrive between the rows of solar modules - this is how the Agri-Solar Park preserves the character of the local landscape and biodiversity. The shading provided by the installed solar modules reduces evaporation on the land, thereby reducing water consumption during cultivation. The 135-megawatt solar park, consisting of six sub-projects, is the first of a total of seven open-space agri-photovoltaic systems in Sicily. The planned total output is around 700 megawatts.

Tracking systems that follow the path of the sun

At EnergyDecentral 2024, exhibitors will showcase a variety of standardized solutions consisting of photovoltaic modules, mounting structures and operation and maintenance systems that can be adapted to the needs of different crops in different climate zones and landscapes. In contrast to conventional monocrystalline modules, which are statically oriented towards the sky, vertically installed bifacial modules also convert direct sunlight on the back pane into electricity. Industry analysts believe that vertical concepts and movable solar trackers will prevail on arable land in the long term. The latter control the solar panels dynamically so that they are always aligned at the optimum angle to the sun. The area directly under the tracker can be used to promote biodiversity, for example by planting a strip of flowers.

In its updated International Technology Roadmap for Photovoltaics (ITRPV), the VDMA, the  association of Germany's engineering industry, also assumes that 60 percent of all PV power plants worldwide will operate with a tracker system in the future. In countries with high levels of solar radiation, such as Spain, they already account for the majority of newly built ground-mounted PV systems. The “Solar Package I”, which has been adopted in the updated German Renewable Energy Sources Act (EEG), came into force in mid-May 2024 and is likely to provide additional momentum in Germany. The target: 215 gigawatts of solar power by 2030.

“In a first step, we developed control sequences that were geared towards the optimal electricity yield of bifacial solar modules or precisely to the needs of a specific plant under agrivoltaics,” explains Dr. Matthew Berwind, team leader at Fraunhofer ISE. The next step is now to combine the two approaches. “Calculating this sweet spot is challenging, but possible thanks to our AI-based concept,” adds Berwind. By early 2025, the researchers plan to refine and validate the digital twin by continuously comparing it with actual performance data.

Open spaces as an opportunity for biodiversity

“The expansion of solar parks offers an opportunity to positively influence biodiversity in our cultural landscape. Well-planned ground-mounted PV systems can provide a refuge for different species groups over several decades,” emphasizes Robert Busch, Managing Director of the German Association of the New Energy Economy (bne). This includes, for example, a wide sunlit strip between the rows of modules and water permeability between the individual modules. In biodiversity PV systems, there is also no fertilization or use of pesticides, but gentle land maintenance without mulching.