Brazilian scientists have developed a slope-based framework for agrivoltaics, finding that sites with slopes less than 15% offer the best balance between agricultural suitability and technical feasibility. Their review of 30 studies shows that steeper terrain is suitable for PV systems with modified designs, land use limits, erosion risks and increasing installation costs.
Researchers from the Federal University of Rio de Janeiro (UFRJ) in Brazil have developed a framework to assess the suitability of soil agriculture for agrivoltaic energy, finding that slopes below 15% provide the most balanced conditions for project implementation.
“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 exhibit characteristics that increase resilience to climate change,” says the corresponding author of the study. José Luiz Gouvêa Gasparini, narrated pv magazine. “Several studies have examined these aspects; however, the ability of agricultural voltaic systems to adapt to different terrain slopes remains evolving. Our team’s theoretical research sought to contribute to narrowing this gap.”
“Countries such as China have installed PV systems on steep terrain to use these areas for energy generation, taking into account agricultural constraints imposed by slopes or climatic conditions. At the same time, most research on agricultural voltaic systems, both experimental and commercial, has been conducted in flat or gently sloping areas,” he continued. “There is an established literature defining threshold conditions for agricultural land capacity, which depend on several factors, including the slope of the site, a key factor for good soil conservation. The structures that support PV panels in agrivoltaic systems in turn vary in terms of height above ground, spatial arrangement and even the amount of light intercepted.”
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The researcher said the proposed typology shows that in agrivoltaic systems, land use constraints, agricultural suitability and land capacity linked to slope become limiting factors before technical constraints affect PV generation.
“In other words, is it technically possible to install agricultural voltaic structures on sites with slopes of more than 30%? Yes, provided that higher installation costs are accepted and technical solutions compatible with appropriate soil management practices are applied to prevent land degradation. However, this may become economically unfeasible depending on the added value of the energy and crops involved,” Gasparini stressed.
In “Soil suitability and technical-construction criteria for slope classification in agricultural voltaic systems”, published in Solar energy, the A Brazilian team has investigated three slope ranges considered most suitable for agrivoltaic energy – up to 5%, 5% to 11% and 11% to 38% – to define a techno-agronomic typology applicable in different geographical contexts.
For each reach, the researchers assessed the degree of mitigation, erosion susceptibility, mechanization limitations and suitability for agriculture. They noted that slopes of 15% to 20% are marginal for crop production due to higher erosion risk and limited use of machinery, while steeper terrain is generally better suited for grazing, forestry or conservation purposes, such as wildlife habitat, recreation and water storage.
They added that an increasing slope increases both installation and operating costs for solar power plants, especially above accepted limits. Steeper angles increase earthwork requirements and risks for ground instability, increasing civil engineering costs. Even slopes greater than 4% can require significant grading and drainage, which affects overall project efficiency. As a result, flat land is generally preferred by investors and developers.
Image: Federal University of Rio de Janeiro, Solar Energy, CC BY 4.0
The team reviewed 30 scientific studies and classified their findings based on technical criteria and land use options. They found that acceptable slope limits for ground-mounted PV systems ranged from 3% to 70%. However, 63% of studies set thresholds below 15%, preferring areas with stronger agricultural potential and lower erosion risk. Slopes above 25% have generally been associated with significant agricultural and mechanization limitations, although they can remain technically feasible for power generation when PV systems are specifically designed for steep terrain.
“This integrated framework shows that, beyond energy feasibility, the sustainability of agricultural voltaic systems fundamentally depends on their compatibility with existing or potential agricultural land uses,” the scientists said. “The reviewed studies using landscape-based multi-criteria analyzes show that slope is not an absolute barrier, but rather a strategic criterion that guides the selection of the most suitable types and configurations of agricultural voltaic systems 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, especially on natural rangelands.
“Future studies with agrivoltaic structures installed on experimental sites with different slope gradients can help validate the proposed typology and improve the understanding of the technical, economic and agronomic limitations of agrivoltaic systems on sloping terrain,” Gasparini said.
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