Selective Solar Panels Pass Some Light to Generate Electricity While Nourishing The Crops Below

Scientists at the University of California, Davis (UC Davis) and the University of Padova have come up with a new approach to energy harvesting, allowing sunlight to be converted into electricity while also feeding crops growing beneath the solar panels.

"This paper is a door opener for all sorts of technological advancements," claims Majdi Abou Najm, associate professor at UC Davis and corresponding author of the paper. "Today’s solar panels take all the light and try to make the best of it. But what if a new generation of photovoltaics could take the blue light for clean energy and pass the red light onto the crops, where it is most efficient for photosynthesis?"

The idea is simple: split sunlight into different colors and figure out which color works best in which task. Blue light, the team found, works best for feeding solar panels to produce electricity — while red light was best for feeding plants to grow food. By building solar panels that absorb one spectrum of light while allowing another to pass through, it's possible to combine the two task in one area.

"We cannot feed two billion more people in 30 years by being just a little more water-efficient and continuing as we do," Abou Najm says. "We need something transformative, not incremental. If we treat the sun as a resource, we can work with shade and generate electricity while producing crops underneath. Kilowatt-hours become a secondary crop you can harvest."

To prove the concept, the team tested specially-constructed panels with tomato plants beneath — having one bathe the plants in blue light, and the other in red. Those under the red light thrived compared to their blue brethren — demonstrating that combining solar generation and agriculture in a single field is, indeed, a potential approach to boosting the availability of both energy and food. Better still, by shading the soil from direct sunlight water usage was cut dramatically.

The team's work has been published in the journal Earth's Future under open-access terms.