Researchers Find Growing Crops at Solar Farms Improves Panel Efficiency
Solar panels mounted over vegetation reveal surface temperature drops
March 7, 2023
Researchers from Cornell University have found that growing commercial crops on solar farms is a potentially efficient use of agricultural land, which can increase both commercial food production and improve solar panel performance and longevity.
The team published the research in Applied Energy.
“We now have a physics-based tool to estimate the costs and benefits of co-locating solar panels and commercial agriculture from the perspective of increased power conversion efficiency and solar-panel longevity,” said lead author Henry Williams, a doctoral student in Cornell Engineering.
The researchers said there is a lot of potential for agrivoltaic systems in which agriculture and solar panels coexist.
They said agrivoltaic systems can potentially help resolve future global food-energy problems.
The research showed that solar panels mounted over vegetation reveal surface temperature drops compared to those arrays built over bare ground.
Solar panels were mounted 4 meters above a soybean crop, and the solar modules showed temperature reductions by up to 10 °C, compared with solar panels mounted a half-meter above bare soil.
The researchers found that the cooling effect due to enhanced evapotranspiration and surface albedo from vegetation and soil is more significant than that induced by greater panel height.
The temperature drops lead to an improved solar panel lifespan and improved long-term economic potential.
“We can generate renewable electricity and conserve farmland through agrivoltaic systems,” said senior author Max Zhang, professor at the Sibley School of Mechanical and Aerospace Engineering.
The method is found to provide increased passive cooling through taller panel heights, more reflective ground cover, and higher evapotranspiration rates compared to traditional solar farms, Zhang added.
The team said understanding this mutually beneficial concept comes at a critical time for agricultural production, as global food demands are expected to increase by 50% by 2050 to feed an anticipated 10 billion people, as estimated by the World Resources Institute.
The study is a step toward evaluating the viability of agrivoltaics in the Northeastern U.S. in relaxing the land-use competition.
For instance, the researchers in their previous study found, in New York, about 40% of utility-scale solar farm capacity has been developed on agricultural lands, while about 84% of land deemed suitable for utility-scale solar development is agricultural.
By using a computational fluid dynamics-based microclimate model and solar panel temperature data, the group evaluated solar panel height, the light reflectivity of the ground, and rates of evapotranspiration (the process where water vapor rises from the plants and soil).
“As you decrease the solar panel operating temperature, you can increase efficiency and improve the longevity of your solar modules,” said Williams, “We’re showing dual benefits. On one hand, you have food production for farmers, and on the other hand, we’ve shown improved longevity and improved conversion efficiency for solar developers.”
In India, a few entrepreneurs are giving agrivoltaics a shot despite the challenges. The number of documented agrivoltaics projects across the country is still in double digits.
In November 2022, a team of researchers at the University of Alcala in Spain claimed that a temperature reduction in solar modules by up to 20ºC can enhance the net system efficiency by about 14%.