Agriculture voltaic offers benefits for agricultural and energy production

The agricultural sector has faced several challenges in recent times, such as extreme weather conditions, war conflicts and lack of inputs and labour, which put risking advances to ensure food security for the world’s population. However, also among agricultural practices, new technologies can help ensure more efficiency, resilience, and sustainability.

One such technology has to do with voltaic, or agrovoltaic, farming, which involves growing crops under solar panels, using the land simultaneously for food and energy production. This increases the efficiency of land use, allowing agricultural and solar farms to share land rather than compete for it.

According to research, there is potential for agrovoltaic systems to provide, through the panels, passive cooling, ground cover and higher evapotranspiration rates compared to traditional solar farms, thus improving both agricultural production and the performance and longevity of solar panels.

Researchers at Cornell University have conducted studies to identify the potential benefits of agri-voltaic systems in terms of food and energy production. The study showed that both can not only coexist side by side, but help improve the microclimate and surface temperature of photovoltaic modules.

“For the first time, we have a physics-based tool to estimate costs and benefits of colocating solar panels and agricultural crops from the perspective of energy conversion efficiency and solar panel longevity,” explains Henry Williams, lead author of the research at Cornell University’s School of Engineering.

For example, in New York, about 40 percent of the capacity of utilitiies-scale solar plants is generated on agricultural land. And about 84 percent of the land considered suitable for solar power generation on that same scale is agricultural, according to an earlier study. In their research on solar power development, engineers have found growing opposition in rural communities to utility-scale projects. According to them, reducing the level of concerns through community engagement is essential to the sustainable growth of solar energy in New York.

Using a computational model of the microclimate based on fluid dynamics and temperature data from the solar panels, the Cornell group assessed the height at which the panels should be installed, the reflectivity of light from the ground and evapotranspiration rates (the process by which water vapour rises from plants and soil). The engineers showed that solar panels installed on vegetation show drops in the temperature of their surfaces compared to those placed on bare ground. Solar panels were mounted four metres above a soya crop and recorded a temperature reduction of up to 10 degrees Celsius compared with those mounted half a metre above bare ground.

The cooling effect due to evapotranspiration and albedo from the vegetation and ground surface is more significant than that induced by the higher height of the panels. This increases the efficiency of solar panels and also their useful life.

This double benefit is extremely welcome as global food demand is expected to increase by 50% by 2050 to feed an estimated 10 billion people, according to the World Resources Institute. In parallel, it is imperative to accelerate the deployment of energy systems based on renewable sources to meet growing energy demand and mitigate the impacts of climate change.

Example of South Korea

Aside from the Cornell study, researchers in South Korea grew broccoli under photovoltaic panels, positioned 2 or 3 metres off the ground and at a 30-degree angle, providing shade and protecting the crops from the weather.

The study revealed that the quality of broccoli was not inferior to that of broccoli grown in the traditional way. There was also no significant change in taste. In addition, the broccoli grown under the panels had a deeper shade of green, making it more attractive to consumers.

In East Africa, agro-voltaic systems are allowing farmers to make better use of land that was previously seen as unviable. A project in Kenya is using solar panels several metres above the ground, with spaces between them, to protect crop plants from heat stress and water loss. This has allowed investment in a wider variety of higher value crops.

A pilot project in France, with 5,500 solar panels on a farm in the northeast of the country, aims to produce 2.5 megawatts at peak times, the equivalent of the energy consumed by 1,350 people, without harming large-scale farming. Capable of following the path of the sun, the panels can move vertically to let rain through. Horizontally, they can produce shade and reduce weather damage.