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July 26, 2024

Biodiversity photovoltaics combines climate protection and sustainable agriculture

July 26, 2024 - Electricity and biodiversity side by side in the field? Solar farms can be built to integrate crops and the natural environment, which can make a valuable contribution to conserving biodiversity. Agri-photovoltaics, the dual use of an agricultural land for both crops and solar energy, is a current topic that will be discussed at EnergyDecentral 2024 in Hanover, Germany from November 12-15. Modern module mounting systems with special panels make it possible to simultaneously grow crops and produce sustainable electricity on agricultural land.

When visitors to EnergDecentral will be discussing what sustainable Agriculture could look like in the future, one term is likely to come up again and again: Agri-photovoltaics, or 'Agri-PV' for short. "This refers to land that can be used for both agriculture and solar energy generation," explains Marcus Vagt, Project Manager, EnergyDecentral. The ambitious German climate protection 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 to be around 1700 gigawatts. In mathematical terms, around four percent of Germany's agricultural land would be sufficient to cover the current electricity demand in Germany.

Solar power from the field

Because of their height of four to six meters, elevated systems are suited to shade-tolerant crops, which could be grown where hail protection nets or protective films are currently placed. With their semi-transparent modules, these systems provide sufficient light for photosynthesis. "Crops in turn benefit from the protection afforded by the solar modules,"explains Professor Dr Andreas Schweiger from the University of Hohenheim, Germany, where he heads the 'SynAgri-PV' research project on the plant-ecological aspects of Agri-PV systems. "It is in the shade that many plants begin to increase the growth of the photosynthetically active leaf material above-ground. This is relevant for lettuce, for example, as this part of the plant is of commercial interest," explains Lisa Pataczek, research associate in the project team.

However, this potential varies according to the climatic conditions and 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 of shading without any significant loss of yield," Schweiger emphasises. 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 loses.

Added value in climate change and tracking systems that follow the path of the sun

But this form of energy generation can do even more. "When water is scarce, plants benefit from less evaporation and therefore less water loss: the yield is higher than on the unshaded areas," says Pataczek. From the researchers' perspective, this stabilising 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," explains Schweiger.  "It will be particularly important for regions that will come to face increasing water scarcity in the future."

At EnergyDecentral 2024, exhibitors will showcase a variety of standardised 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 agricultural areas. In contrast to conventional monocrystalline modules, which are statistically oriented towards the sky, vertically installed bifacial modules capture direct sunlight on both front and back panes and convert this into electricity. Industry analysts generally agree 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.

Optimum yield through deep learning

"We see great potential for tracked systems with perfectly coordinated tracking algorithms, particularly in the field of agrivoltaics with its many different crops and systems," says Hannes Elsen, Product Manager at Zimmermann PV. In the 'DeepTrack' research project, the company from Eberhardzell therefore built a tracked PV system on the Fraunhofer ISE test field in Freiburg, Germany. Based on this, the project consortium developed a digital twin that links monitoring and modelling tools with weather forecasts thanks to deep learning.

"In a first step, we developed control sequences that were geared towards the optimal elecriticity 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," says Berwind. By early 2025, the researchers want 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 photovoltaic (PV) systems can provide a refuge for different species groups over several decades," emphasises 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 neither fertilisation nor the use of pesticides, but instead gentle area maintenance without mulching. "If biodiversity PV becomes the standard, tens of thousands of hectares will be protected for biodiversity every year." At the same time, biodiversity PV is attractive for farmers: while land is permanently lost in traditional solar farms, its status as 'agricultural land' is retained.

DLG's biodiversity projects

The DLG, the organiser of EnergyDecentral and EuroTier is active in several biodiversity projects, including “BioMonitor4CAP” (Project number 101081964) funded by the European Union's Horizon Europe research and innovation program, that aims to develop, evaluate and test affordable and reliable systems for monitoring biodiversity for application on agricultural land. DLG is also partner of the ConservES project for research on increasing biodiversity in intensive wheat farmland across four EU countries.

For more information, visit HERE.

The Global Miller
This blog is maintained by The Global Miller staff and is supported by the magazine Milling and Grain
which is published by Perendale Publishers Limited.

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