Growing Crops Under Solar Panels Could Substantially Boost Energy Production
Agrivoltaics is a term we'll probably be hearing a lot more of in the coming years.
Often known as solar sharing, agrivoltaics is where solar technology meets traditional farming. These systems are straightforward: Solar panels are installed at a higher level so that plants can grow underneath them. While this may seem counterintuitive, too much sunlight can actually stress the plants, and shading the crops means they will need less water, which usually evaporates quickly in an open field. Furthermore, plants "sweat," cooling the panels above and increasing their efficiency. This results in a win-win situation in which land productivity is maximized.
A high-profile study offers a new perspective
While this system has gained popularity in recent years; few studies have thoroughly tracked and examined all aspects of the associated processes. Now, in a new study published in Nature Sustainability, which is based on an exhaustive investigation of incoming sunlight, air temperature, and relative humidity, researchers have discovered that current croplands are the “land covers with the greatest solar PV power potential," according to a press release.
To conduct the study, the University of Arizona researchers led by Greg Barron-Gafford, an associate professor in the School of Geography and Development, established the first agrivoltaics research site at Biosphere 2, the living laboratory where climate change has recently been the focus of interdisciplinary research.
The researchers focused on chiltepin pepper, jalapeno, and cherry tomato plants grown beneath a solar photovoltaic, or PV, panel array. During the average three-month summer growing season, researchers used sensors mounted above the soil surface to continuously record incoming light levels, air temperature and relative humidity, and soil surface temperature and moisture.
Solar panels could give farms a new life
They discovered that the agrivoltaics system had a considerable impact on three plant growth and reproduction factors: air temperatures, direct sunlight, and atmospheric demand for water. The PV panels' shadow resulted in cooler daytime temperatures and warmer overnight temps than the traditional method. The system also had a reduced vapor pressure deficit, indicating that there was more moisture in the air.
For example, jalapenos produced a similar amount of fruit in both, but with 65 percent less transpirational water loss in agrivoltaics system. The researchers think these findings suggest we could reduce our water use but still maintain levels of food production.
"We found that many of our food crops do better in the shade of solar panels because they are spared from the direct sun," explained Baron-Gafford, in a press release. "In fact, total chiltepin fruit production was three times greater under the PV panels in an agrivoltaic system, and tomato production was twice as great!"
Since solar panels' performance decreases as they warm, plants reducing their temperature boosted energy production efficiency.
"Those overheating solar panels are actually cooled down by the fact that the crops underneath are emitting water through their natural process of transpiration – just like misters on the patio of your favorite restaurant," Barron-Gafford explained. "All told, that is a win-win-win in terms of bettering our how we grow our food, utilize our precious water resources, and produce renewable energy.”
Another upside is that agrivoltaics could also benefit farm laborers who are at risk of heat stroke and heat-related death since preliminary results show that working in an agrivoltaics region can keep the skin temperature about 18°F (-7.778°C) cooler than the traditional alternative.
The study looks incredibly promising, but researchers say there needs to be more research with additional plant species. The team is currently collaborating with the U.S. Department of Energy's National Renewable Energy Lab to analyze how effectively agrivoltaics can work in other regions and help the agriculture industry as it suffers the worst effects of climate change.