Researchers from the Federal University of Rio de Janeiro (UFRJ) in Brazil have developed a framework to assess soil agricultural suitability for agrivoltaics, finding that slopes below 15% provide the most balanced conditions for project deployment.
“Agrivoltaic systems have great potential, not only because they allow the same land to be used simultaneously for energy and food production, but also because they present characteristics that enhance resilience to climate change,” the research’s corresponding author, José Luiz Gouvêa Gasparini, told pv magazine. “Several studies have addressed these aspects; however, the capacity of agrivoltaic systems to adapt to different terrain slopes remains incipient. The theoretical study conducted by our team sought to contribute to reducing this gap.”
“Countries such as China have been installing PV systems on steep terrain in order to utilize these areas for energy generation, considering agricultural limitations imposed either by slope or climatic conditions. At the same time, most research involving agrivoltaic systems, whether experimental or commercial, has been carried out in flat or gently sloping areas,” he went on to say. “There is well-established literature defining threshold conditions for agricultural land capability, which depend on several factors, including terrain slope, a key determinant for proper soil conservation. The structures that support PV panels in agrivoltaic systems, in turn, vary in terms of height above the ground, spatial arrangement, and even the amount of light intercepted.”
The researcher said the proposed typology shows that, in agrivoltaic systems, land-use constraints, agricultural suitability and land capability linked to slope become limiting factors before technical restrictions affect PV generation.
“In other words, is it technically possible to install agrivoltaic structures on terrain with slopes above 30%? Yes, provided that higher installation costs are accepted and that engineering solutions compatible with appropriate soil management practices are adopted to prevent land degradation. However, this may become economically unfeasible depending on the added value of the energy and crop involved,” Gasparini emphasized.
In “Soil suitability and technical-construction criteria for slope classification in agrivoltaic systems,” published in Solar Energy, the Brazilian team investigated three slope ranges considered most suitable for agrivoltaics – up to 5%, 5% to 11%, and 11% to 38% – to define a techno-agronomic typology applicable across different geographic contexts.
For each range, the researchers assessed the degree of limitation, erosion susceptibility, mechanization constraints, and agricultural suitability. They noted that slopes of 15% to 20% are marginal for crop cultivation due to higher erosion risk and restricted machinery use, while steeper terrain is generally better suited to pasture, forestry, or conservation purposes such as wildlife habitat, recreation, and water storage.
They added that increasing slope raises both installation and operating costs for solar plants, particularly beyond accepted limits. Steeper angles drive up earthwork requirements and soil instability risks, increasing civil engineering costs. Even slopes above 4% can require substantial grading and drainage, affecting overall project efficiency. As a result, flat land is typically preferred by investors and developers.
Image: Federal University of Rio de Janeiro, Solar Energy, CC BY 4.0
The team reviewed 30 scientific studies, classifying their findings by technical criteria and land-use capability. They found that acceptable slope limits for ground-mounted PV systems ranged from 3% to 70%. However, 63% of the studies set thresholds below 15%, favoring areas with stronger agricultural potential and lower erosion risk. Slopes above 25% were generally associated with significant constraints on agriculture and mechanization, although they may remain technically viable for power generation when PV systems are specifically designed for steep terrain.
“This integrated framework shows that, beyond energy feasibility, the sustainability of agrivoltaic systems fundamentally depends on their compatibility with existing or potential agricultural land use,” the scientists said. “The reviewed studies employing landscape-based multicriteria analyses show that slope is not an absolute barrier, but rather a strategic criterion guiding the selection of the most appropriate agrivoltaic system types and configurations for each territorial context.”
They also found that areas with slopes of 15% to 30%, classified as conditionally suitable, can remain viable if appropriate engineering solutions and soil management practices are implemented to prevent degradation. Given the limitations for conventional agriculture, vertical agrivoltaic systems may be more suitable in these areas, particularly on natural pastureland.
“Future studies involving agrivoltaic structures installed on experimental sites with different slope gradients may help validate the proposed typology and improve understanding of the technical, economic, and agronomic limitations of agrivoltaic systems on sloping terrain,” Gasparini said.
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