Have you heard of agrivoltaics? Well, if you haven’t, listen up, because it’s the way of the future. Agrivoltaics refers to the intentional placing of agricultural fields close to solar photovoltaic panels with the purpose of improving food production and sustainability hand in hand. New research published recently in Nature Sustainability from the University of Arizona sheds light (no pun intended) on how solar sharing, as the phenomenon is also known, can have positive impacts on food production, water savings and the efficiency of electricity production.
The idea of agrivoltaics comes from the realization that croplands are the "land covers with the greatest solar PV power potential," according to another recent study in Nature that analyzed incoming sunlight, air temperature and relative humidity in these habitats. That obviously begged the question: can we be using croplands more efficiently?
"Many of us want more renewable energy, but where do you put all of those panels? As solar installations grow, they tend to be out on the edges of cities, and this is historically where we have already been growing our food," said lead author Greg Barron-Gafford, an associate professor in the School of Geography and Development.
"So which land use do you prefer -- food or energy production? This challenge strikes right at the intersection of human-environment connections, and that is where geographers shine!" said Barron-Gafford. "We started to ask, 'Why not do produce both in the same place?' And we have been growing crops like tomatoes, peppers, chard, kale, and herbs in the shade of solar panels ever since."
To conduct the study, researchers planted chiltepin pepper, jalapeño, and cherry tomato plants under normal direct sunlight conditions and under solar photovoltaic (PV) panels. Under these two conditions, they also varied the amount of water the plants received, from daily irrigation to irrigation every second day. From there, the researchers measured incoming light levels, air temperature and relative humidity, soil surface temperature and moisture at a depth of 5 centimeters, and several other factors during the three-month summer growing season.
The results that they found were incredible across the board. Not only did the shade provided by the PV panels improve crop production for those crops planted underneath them, but the transpiration from the crops reduced overheating of the PV panels themselves and made them more efficient for energy production. The panels additionally decreased the rate of transpiration from the plants and produced a lower vapor pressure deficit, meaning there was more moisture in the air and PV panel crops needed less irrigation.
"We found that many of our food crops do better in the shade of solar panels because they are spared from the direct sun," Baron-Gafford said. "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! At the same time, we found that each irrigation event can support crop growth for days, not just hours, as in current agriculture practices. This finding suggests we could reduce our water use but still maintain levels of food production," Barron-Gafford commented, adding that they also saw soil moisture 15% higher in the agrivoltaics system than the control plot given the less-frequent irrigation option. And just to add to the excitement, the agrivoltaics systems also make croplands cooler for farmers and could thus help reduce heat stroke and heat exhaustion for farmers who spend long days in direct sunlight.
"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," said Barron-Gafford.