As California farmers face worsening drought, extreme heat and rising costs, the state is racing to expand solar energy infrastructure. But both agricultural production and solar harvesting depend on one increasingly scarce resource: land.
Researchers at UC Davis are looking at whether combining farming and solar energy could help farmers adapt.
The approach, called agrivoltaics, combines farming below or alongside solar panels. Scientists are studying whether strategically placing panels could provide enough shade to help crops withstand some of the stresses of climate change — while also giving farmers another potential source of income.
At UC Davis, a proof-of-concept site is in its first year of operation and gives researchers a larger setting to test whether agrivoltaics can be applied to typical farms.
Growing in the shade
Graduate researcher Gavin Chaboya points to a row of tomatoes growing near a set of solar panels.
“Where we’re at right now is the second row closest to a west-facing solar panel,” Chaboya says. “We still have some sun scald.”
Sunscald happens when crops are exposed to too much direct sunlight and extreme heat.
The panels are positioned vertically along the field, creating different levels of shade as the sun moves throughout the day. Chaboya compares another row, closer to the panels.
“We’re looking at the row closest to the panel now. You could see leaf development is much smaller, the fruits themselves are tinier, and the sun scalding is a lot less,” he says.
These vertical panels are one of three configurations researchers at the site are using to see how crops respond to different levels of shade and other changes in their growing environment.
Chaboya says the team began studying agrivoltaics roughly five years ago, first using small experimental plots to observe how plants responded to light filtered through different materials.
Chaboya says the California Department of Food and Agriculture provided three years of funding to study both summer and winter crops.
The differences in agricultural outputs are what researchers are trying to understand. Shade from the panels could potentially reduce heat stress on crops, help conserve water and alter conditions in the soil beneath them, according to Chaboya.
He sees the approach as fitting within regenerative agriculture.
“When we’re talking about shielding soil from getting dried up by the sun, protecting plants from burning up in high heat… . If agrivoltaics wasn’t added into this umbrella term of regenerative ag, I don’t know what else it could fall under,” Chaboya says.
State lawmakers last year defined regenerative agriculture to include outcomes that lead to healthier and more resilient farms, while also improving farmer livelihood. California’s outcome-based framework is broad and does not prescribe a specific list of practices.
That definition could matter for agrivoltaics.
If the practice is recognized as regenerative agriculture, it could eventually lead to funding for farmers who want to co-locate solar panels and crops or livestock.
The concept is appealing for another reason: Farmers could potentially use the electricity on their own operations or sell it, creating a secondary source of income from the same piece of land.
While it remains to be determined whether farms classified as regenerative could qualify for grants to support solar energy projects, California is already putting money into research to determine whether agrivoltaics can work at the scale farmers would need.
The questions — and answers — of agrivoltaics
California Department of Food and Agriculture Secretary Karen Ross says research from other states can’t necessarily be applied to California farms.
She says that’s one reason CDFA invested in the UC Davis project.
“I think there’s a lot of opportunity there and obviously the interest for just energy and climate resilience, being able to produce more energy on the land for your own operations would be a really huge asset for the farming community,” she says.
California has a history of pioneering new approaches to agriculture. The state was the first to establish a legal definition for certified organic farming, a label that comes with strict rules like prohibited substances, mandatory inspections and record keeping. The move later influenced national policy.
“That did have quite a bit of influence on the national standard,” Ross says.
But not all researchers are convinced agrivoltaics is ready for widespread use in California.
UC Berkeley agricultural and resource economics professor Aaron Smith says there is a fundamental challenge in trying to produce food and electricity on the same piece of land.
“The challenge with doing agriculture and electricity generation on the same piece of land is that if one of those makes the other one worse, then you might end up doing two things badly when you could have just been doing one thing well,” he says.
Smith says that, at least for now, it would be more efficient to divide the land between agriculture and solar rather than combining the two. He also questions whether public funds should be used to encourage farmers to adopt agrivoltaics before researchers have established that the practice works economically and agriculturally.
“Paying farmers to do agrivoltaics right now I don’t think is a good use of funds,” Smith says. “Maybe it would be a good use of funds at some point in the future… but I don’t think we’re close to that point.
Smith does support continuing to fund research for scientists to better understand where the technology could be implemented in the future.
That is also the goal at UC Davis.
Chaboya says researchers need much larger test sites that more closely resemble the conditions farmers would encounter in the real world before they can say whether agrivoltaics makes sense at scale.
“You just need to have these large-scale test plots which mimic the environment before we can actually have any definitive saying as to what we can do large scale,” he says.
Researchers track tomato development and water use, using sensors to measure changes in factors such as light and wind that can influence crop growth and yields, Chaboya says.
And ultimately, the researchers will need to determine whether any benefits to the crops outweigh the costs and tradeoffs of putting solar infrastructure in the field.
Until then, Chaboya says he’ll continue studying what the panels are actually doing to the crops — one tomato at a time.
“Really, time will tell,” he says. “All I’m doing right now is just measuring tomatoes and hoping for the best.”
This story was produced by the Climate Solutions Studio, a project of the Central Valley Journalism Collaborative and its partner newsrooms. CapRadio is a founding partner.
