Plants and solar panels seem to be in indirect competition for sunlight. However, research shows that it could be the opposite – solar panels are actually beneficial to plants.
In a study led by the University of Arizona’s Greg Barron-Gafford, the researchers found, solar panels and plants can have a favorable combination towards solar-agriculture. For the study, Prof. Barron-Gafford focused on drier areas such as the American Southwest, where water is limiting for crops.
The experiment showed that the shade provided by the solar panels lowers soil temperature and reduces evaporation. On the other hand, plants can keep the ground soil colder than bare ground, which increases the efficiency of solar panels; when solar efficiency increases, the amount of electricity generated goes up as well.
For the study, the team came up with three set-ups where the first one is only solar panels, the second is only plants, and the third is the combination of both. The plots are built higher than a typical set-up, which was 3 meters above the ground. All control trials are irrigated and with tracked temperatures, soil moisture, and humidity. The crops used are cherry tomatoes, chiltepin peppers, and jalapeños.
As expected, the results varied and showed better in the combination of crops and solar panels. The air temperature was 1°C cooler during the day, but 0.5°C warmer at night. Solar panels are 9°C cooler as well, due to the plants beneath it. The air was less dry, and the soil evaporated more slowly for the set-up with solar panels.
Some of the plants also showed positive results. CO2 uptake was 33% higher in the combined plot with chiltepin peppers. Water-use didn’t increase for the crops as soil moisture is used more as the plants grew. The number of peppers produced increased three times under the solar panels, as well.
For the jalapeños, it used 11% less CO2 being under the panels. Water efficiency increased, where the plants used 65% less water. For the crops produced, on the other hand, it dropped slightly but not more than the margin error.
A 65% increase in CO2 uptake was seen in cherry tomatoes, as well as a spike of 65% in water-use efficiency. The crops also produced twice more fruits using the same amount of water.
According to calculations, the cooler temperature in the combination results in the increase of electricity generation by about 3% during summer, which means a 1% power gain a year.
According to researchers, results show a potential benefit to solar-agriculture. For certain crops, it could help farmers save water, gather more vegetables, and reap the rewards from using solar panels for generation of energy. It’s a potential worth investigating and improving, researchers say.
Watch this video that explores the subject in more detail: