Agri-PV brings together the best of agriculture and solar power generation. The question remains: how do solar installations influence land management and crop yields? Early findings suggest that the benefits are measurable.
The journey begins in a landscape that is marked by transformation. Moving through the Garzweiler opencast mine in the Rhineland, excavators work steadily, pulling lignite from the ground for power generation. For decades, this vast terrain has been out of reach for agricultural use.
Yet change is taking root at the mine’s edge. The energy transition, now closely linked with agriculture, is taking shape right next to the mining site. On a seven-hectare parcel between the mine and the A44 motorway near Bedburg, RWE has commissioned three Agri-PV installations totalling 3.2 megawatts. August 2024 saw all three systems come online.
Three technologies, one field
Each of the three systems employs a distinct technological approach. In one part of the site, a raised solar array creates a canopy where a local farmer cultivates raspberries in containers. On another part of the land, RWE has installed vertically oriented modules using the Next2Sun system. Here, the rows are spaced widely enough to prevent mutual shading of the panels, ensuring there is ample room for agricultural machinery to operate efficiently.
Unrestricted movement between modules
The third Agri-PV configuration introduces a tracker system from Schletter, designed with flexibility and efficiency in mind. When it is time for fieldwork, the farmer can reposition the modules horizontally at the touch of a button. This allows tractors, fertiliser spreaders and sprayers to move easily beneath the panels. Even a combine harvester can pass through without issue – the cutting header glides under the modules as the machine travels down the centre of the row. “The process runs smoothly,” confirms Gregor von Danwitz, Agri-PV specialist at RWE.
Farmers working with the system have reported no difficulties manoeuvring between the module rows. “The tractors operate with GPS steering, so navigation is both accurate and straightforward,” von Danwitz explains. “We also trialled operation without GPS, and drivers managed well. In the future, however, GPS guidance should be standard, as the technology is valuable and enables greater precision.” The only notable challenge has been occasional signal loss, triggered by the electrical fields generated by the installation. “In those moments, the tractor simply continues straight ahead until it regains the signal and adjusts its course,” he adds.
Horizontal positioning of the modules offers an additional benefit during fieldwork: less dust accumulates on the panels compared to when they are angled.
Maximising yield with trackers
To maintain full agricultural access, the tracker rows are spaced ten metres apart. Each mounting post allows for a one-metre safety buffer, leaving nine metres between the trackers for active cultivation. The margin is narrow – farmers require at least 1.85 metres for their machinery to turn, as von Danwitz points out. “That’s why we plan to increase the safety buffer to one metre on each side in future projects, doubling the allowance compared to Bedburg,” he says. “Over the long term, we intend to widen the spacing to twelve or even fifteen metres, with two-metre safety zones.”
The impact on energy output is substantial. “With trackers, we can install just over twice the generating capacity compared to vertical mounting on the same area, and the energy yield is nearly three times higher,” von Danwitz explains. “For future projects, we will always choose tracking systems wherever the site and ground levelling allow. Only on steep terrain will we opt for vertical systems, as trackers are not feasible there.”
Looking ahead, RWE plans to install a control box at the field’s edge. “This will make it possible to move individual rows or tables in groups, so the entire solar park doesn’t need to be shut down during fieldwork,” says von Danwitz.
Improved water balance
The demonstration project places equal emphasis on agricultural yield and energy generation. During the first year, a range of cereal crops was sown between the solar modules and on a reference plot left free of installations. “Winter wheat was planted on 8 November 2024, with spring barley and spring wheat following in April 2025,” explains Gregor von Danwitz. With the harvest now complete by a farm from Grevenbroich, the initial results are in. The focus extended beyond headline yields to include factors such as soil moisture distribution – a crucial metric for sustainable agriculture.
Rainfall was measured both beneath the trackers and at designated reference points. “Interestingly, we sometimes saw more water accumulating in the safety strips than in the control zone, as rainwater runs off the modules and is redirected by wind,” von Danwitz notes. “At times, there was even greater moisture directly under the trackers than on the reference plot. Evaporation rates were also markedly lower. While the reference area became extremely dry after six rainless weeks, the soil beneath the modules retained enough moisture for continued plant growth.”
More Information on Solar Energy and Farming
- Additional expert knowledge on the topic of photovoltaics you will find in the Magazine “Photovoltaik”.
- In the section ‘Photovoltaics in Agriculture,’ you will find in-depth information on Agri-PV and solar technology in the agricultural sector."
- The special feature ‘Solar Solutions for Farmers’ brings together additional articles under the overarching theme ‘Paths to a Double Harvest,’ exploring how to make the dual use of agricultural land for generating solar energy, crops, and specialty crops as successful as possible
Outstanding grain quality
Temperature readings under the modules revealed further agricultural benefits. The microclimate there is about one degree cooler than on the reference plot, and on particularly hot days, the difference can reach up to three degrees Celsius, according to von Danwitz. These combined effects translate directly into crop yields. The first year of trials showed that grain yields from both Agri- PV systems matched those of the reference plot. In fact, crops grown beneath and between the modules demonstrated slightly superior quality, especially in terms of protein content.
The grain proved suitable for milling into flour for baked goods or for use in breweries, rather than being relegated to animal feed.
LED lighting for crops
The pergola-style, elevated module installation has delivered robust results. Healthy plants have flourished in pots beneath the panels, even though no semi-transparent modules were used. For raspberries, the reduced direct sunlight presents no real obstacle. The farmer has also gained more control over harvest scheduling, as the crop is less exposed to weather swings and harvest workers benefit from improved protection.
For fruit varieties that require more sunlight, further refinements are already under consideration. “In those cases, LED lamps powered by solar energy could be deployed,” explains Gregor von Danwitz. He believes only short lighting periods are needed – two hours each morning, when sunlight usually supports photosynthesis, should be enough. This supplementary lighting would only be required for four weeks after flowering and four weeks before harvest.
Ample light for grapevines
Elevated solar canopies are also pointing the way forward for viticulture. Researchers at Geisenheim University are exploring how this approach can be integrated into vineyards. In the Rheinhessen region, they have installed semi-transparent solar modules on elevated trackers above part of a vineyard, allowing the panels to follow the sun’s path. Their research focuses on how the shading from these modules influences vine growth and health.
The 94-kilowatt installation was constructed without sealing the soil. “Thanks to the semi- transparent modules, the area beneath the canopy remains pleasantly bright, with a balanced temperature profile,” says Manfred Stoll, head of the Institute of General and Organic Viticulture at Geisenheim University. “There is no complete shade beneath the panels.”
Buds protected from late frost
In Geisenheim, researchers have found that vines beneath the solar modules not only show accelerated growth but also benefit from vital protection against late spring frosts. “One of the greatest threats facing viticulture and agriculture in general is the increasingly early onset of plant development,” explains Manfred Stoll. “Last year, by the end of April, we already had shoots with two or three leaves. Then the temperature dropped to minus one degree Celsius. For many vineyards, that’s a catastrophe. Yet here, if the temperature falls below 0.4 degrees Celsius at two in the morning, the heating system activates automatically.”
This system draws its power from electricity generated by the solar modules, which is stored locally for such events. While modest in size, the heater is sufficient to keep the temperature just above freezing, and last year, it proved critical in saving the harvest.
Preserving wine quality
The presence of solar modules also helps to maintain grape quality as climate change accelerates. Earlier plant development now makes vines not only more vulnerable to late frosts, but also hastens increases in must weight (the sugar content of grape juice) and sugar content, while acidity declines more rapidly, as Claudia Kammann, from the Institute for Applied Ecology and Professor of Climate Impact Research on Special Crops, notes.
These changes challenge the production of balanced wines. “Traditionally, these grape varieties in cooler northern climates produce lighter wines with lower alcohol, higher acidity and pronounced freshness,” Kammann explains. “That’s exactly what climate change now puts at risk.” The solar canopy, however, can slow the ripening process. “This effect is real. We’re able to delay ripening by about nine to ten days. Of course, that varies year by year and depends on the prevailing climate conditions,” says Kammann.
Better protection against mould
While biomass yields under the solar modules are slightly reduced compared to the reference area, the protective effect of the modules enables wine quality to be maintained, even as vegetation periods start earlier and progress more rapidly. The vines also benefit from enhanced protection against environmental stressors. It’s not just hail and heavy rain that the modules shield against; they also help reduce the risk of disease. “One pattern we’ve observed is that in wet years, Botrytis, a grey mould, becomes a concern,” explains Claudia Kammann. “This fungal disease infiltrates the grapes, and when berries swell after heavy rainfall and press together, the risk of infection rises sharply.”
This risk intensifies during humid spells in the ripening phase. “Wet weeks or months before harvest are particularly problematic,” Kammann notes. “Yet here, under the shelter of the modules, we’ve seen significantly fewer issues with Botrytis,” she adds, pointing to a decisive advantage of solar canopies in viticulture.
These early successes show that Agri-PV can deliver tangible benefits for both farmers and energy producers. As technology and practice evolve, dualuse solutions like these will play a vital role in building a resilient and sustainable future for agriculture and renewable energy.
Text: Sven Ullrich, Photovoltaik
