Soil protection measures can make agri-photovoltaics more sustainable
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Agri-photovoltaics combines electricity generation and agriculture on the same land—to ensure this works well in the long term, it is worth taking a closer look at the soil. Researchers at the Leibniz Centre for Agricultural Landscape Research (ZALF) have, for the first time, measured how the construction phase of agri-photovoltaic installations affects soil structure.
Their study, published in the journal Scientific Reports, shows that heavy construction machinery can compact the soil in places to such an extent that plant roots subsequently struggle to grow. The good news is that such compaction can be largely avoided through targeted soil protection measures during construction.
The researchers investigated a newly built agri-photovoltaic plant at the ZALF research site in Müncheberg, Brandenburg. This plant combines agriculture with solar power generation on the same plot of land. Once construction work was completed in fall 2024, they took soil samples and assessed, directly in the field, the extent to which the predominantly sandy soil had been compacted.
The result: In the areas where construction had taken place, subsoil density ranged from 1.67 to 1.69 grams per cubic centimeter. Individual measurement points reached values of 1.86 to 1.99 grams per cubic centimeter. By comparison, values on an uncompacted control plot were only 1.14 to 1.34 grams per cubic centimeter. The soil’s resistance to root penetration was also significantly higher, reaching 3.7 to 4.1 megapascals at medium depths.
Kathrin Grahmann, lead author of the study from ZALF, explains: “These values are well above the thresholds known for these soil types, beyond which plant root growth is restricted. In the case of sandy soils, such as those examined in our study, this is particularly problematic because they find it difficult to recover on their own.”
Why sandy soils are particularly at risk
Sandy soils have a weak soil structure and low carbon content, and they can barely regenerate on their own once compacted. Unlike clayey soils, they lack the ability to swell through natural processes such as freezing and thawing, or to become looser again through the action of soil organisms.
Heavy machinery was used during construction. The work took place in damp soil conditions in the fall, which further contributed to compaction. In the three weeks before construction began, 32 millimeters (1.3 inches) of rain fell, with a further 83 millimeters (3.3 inches) during construction.
The study shows that compaction occurred not only directly around the solar panel supports but also across the entire agricultural area between the rows of panels. This was due to frequent passage of construction machinery during installation.
Consequences for agriculture and recommendations for action
Soil compaction can have several negative consequences: Roots grow less effectively, water seeps in more slowly and crop yields may ultimately decline. Studies show that, at similar levels of compaction, winter rye yields can fall by 22% to 43%.
The researchers recommend that soil science supervision during construction become standard practice in future agri-photovoltaic projects. Qualified specialists would monitor the work and ensure that protective measures are implemented. These include restricting vehicle traffic to designated tracks, using ground protection plates and avoiding construction work when the ground is damp.
In the current study, such measures were not implemented because of the high cost of soil protection mats, delays in installation and tight deadlines imposed by funding agencies. Following installation, mechanical and biological measures to aerate the soil were carried out at the study site, including the cultivation of alfalfa over a period of two to three years.
What does this mean for the future?
Agri-photovoltaic systems are being built with increasing frequency in Europe, as they are intended to help drive the energy transition while continuing to use agricultural land for food production. However, the study shows that, without suitable protective measures, soil fertility may suffer in the long term.
Future research should investigate whether the results also apply to other soil types and system configurations. Long-term monitoring of soil recovery following installation is also important. The costs of soil-conserving construction measures are difficult to quantify in general terms, but soil protection slabs and specialized machinery are estimated to cost several thousand euros per hectare. These costs would have to be borne by the project operators.
Avoiding agri-photovoltaics and using separate land for agriculture and energy production would prevent soil compaction but would require more land. Lighter construction machinery or the use of agricultural robots following installation could also help protect the soil.
Publication details
Kathrin Grahmann et al, Construction-induced soil compaction in agri-photovoltaic systems: evidence from an Arenosol, Scientific Reports (2026). DOI: 10.1038/s41598-026-65268-z
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Leibniz-Zentrum für Agrarlandschaftsforschung
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Soil protection measures can make agri-photovoltaics more sustainable (2026, September 27)
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