Harvesting Light to Grow Food and Clean Energy Together

Different Light Spectra Serve Different Needs for Agrivoltaics

by Kat Kerlin
December 06, 2022

solar filters emit a red light over tomato plants in an outdoor research field at �鶹��ý — Solar filters emit a red light over tomato plants growing in a research field at �鶹��ý in 2022. The work further tests the findings of a �鶹��ý study showing plants in agrivoltaic systems respond best to the red spectrum of light while blue light is better used for energy production. (Andre Daccache/�鶹��ý)

People are increasingly trying to grow both food and clean energy on the same land to help meet the challenges of climate change, drought and a growing global population that just topped 8 billion. This effort includes agrivoltaics, in which crops are grown under the shade of solar panels, ideally with less water.

Now scientists from the University of California, Davis, are investigating how to better harvest the sun — and its optimal light spectrum — to make agrivoltaic systems more efficient in arid agricultural regions like California.

, published in Earth’s Future, a journal of the American Geophysical Union, found that the red part of the light spectrum is more efficient for growing plants, while the blue part of the spectrum is better used for solar production.

Solar filters in agrivoltaic system cast blue light on tomato plants at �鶹��ý research field — Solar filters emit a blue light over tomato plants growing in a research field at �鶹��ý in 2022. (Andre Daccache/�鶹��ý)

A door opener

The study’s results could help guide global interest in agrivoltaics and identify potential applications for those systems.

“This paper is a door opener for all sorts of technological advancements,” said corresponding author , an associate professor at the Department of Land, Air and Water Resources and a fellow at the �鶹��ý . He conducted the study with first author Matteo Camporese of the University of Padova in Italy, who came to �鶹��ý as a Fulbright visiting scholar. “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?”

For the study, the scientists developed a photosynthesis and transpiration model to account for different light spectra. The model reproduced the response of various plants, including lettuce, basil and strawberry, to different light spectra in controlled lab conditions. A sensitivity analysis suggested the blue part of the spectrum is best filtered out to produce solar energy while the red spectrum can be optimized to grow food.

solar filters over tomato plants on research field at �鶹��ý with illustrated thermal color bar running vertically — Solar filters shade tomato plants in a research field at �鶹��ý as part of an agrivoltaic research study. (Majdi Abou Najm/�鶹��ý)

thermal image of crops growing beneath solar panels at �鶹��ý — The same plants and solar filters shown with thermal imaging. The color changes illustrate the reduced temperatures in the shade of the panels. (Majdi Abou Najm/�鶹��ý)