Efforts to Mix Farming and Solar Energy Grow

"As solar farms fan out across the landscape, some worry they will displace actual farmland. The solution: Why not grow food and produce solar energy on the same plot?

Boosted by solar-industry support and government funding, researchers are exploring new ways to combine agriculture and solar power. In Ohio, operations have begun on a large-scale U.S. farm producing both crops and solar energy, one of the first of its kind.

Despite the advances, "agrivoltaics" -- a loosely defined term that describes solar energy production combined with grazing, pollinator habitats or crops -- remains niche, in part because merging the two industries can drive up the costs of solar-energy production and reduce agricultural productivity. A recent government estimate found that about 1% of solar power comes from agrivoltaic sites.

Some advocates envision a future where no solar farm gets permitted without a promise to graze cattle or grow alfalfa. Others worry that developers' much-touted agrivoltaics efforts, like projects that grow pollinator-friendly plants, are little more than "bee-washing" public relations campaigns to win community buy-in on big projects.

On a recent Zoom call, Cornell University researcher Jared Buono pulled up an animation that showed solar panels rotating to position their faces away from the sun, allowing direct light to shine on crops beneath them. Buono is researching how these "antitracking" panels, which move away from sunlight instead of following it, can coexist with delicate crops like grape vines and peach trees.

Buono said he had expected the system to result in trade-offs, resulting in lower energy output and lower crop yield. Instead, some data have shown the panels helping the crops. In France, for example, panels have been used to keep grape vines in the shade during a heat wave. "They saved the crop, so it was a 30% increase in yield," Buono said. Similarly, during a cold snap, closing solar panels above a crop could keep the air beneath a few degrees warmer and prevent frost damage.

Buono's experiments are what he calls an "agriculture-first approach." He is focused on how solar panels can help farmers protect their crops. Researcher Madhu Khanna, environmental economist at the University of Illinois Urbana-Champaign, is leading a $10 million grant project funded by the Agriculture Department that focuses on optimizing the output for both solar and energy, a metric called combined yield.

A challenge for maximizing combined yield is reimagining panel spacing and height to accommodate farming. Typical arrays consist of solar panels fitted to frames that are 4 feet high, which is too low for farm equipment. But "the cost of the panels really goes up exponentially as the height goes up," Khanna explained.

Her team is planting soybeans, which grow in squat bushes, beneath 6-foot frames, which are more expensive than 4-foot models but less pricey than taller ones. They are also spacing the rows of panels farther apart to make space for the crops and farm machinery. The goal is to land on a design that is more productive as a combined solar-crop installation than as one or the other.

Despite all the recent experiments with agrivoltaics, for farmers who own a substantial amount of land, the most financially appealing way to get involved with solar is often to simply lease a portion of the farm to developers. 

"From an economic perspective, the leases for solar farming are three to four times higher than for crop production," Khanna said.

Buono, the Cornell researcher, said his work has generated interest from solar developers -- until they learned about the cost.

"I brought up $5 a watt, and you could see the whole room deflate," he said. The median cost for utility-scale solar projects was $1.32 a watt in 2022, according to the Lawrence Berkeley National Laboratory. "They were like, 'OK, well, you know, we're going to have to look into this in the next few years and see where it goes.'"

Nationwide, only 0.3% of U.S. farmland is expected to be used for solar energy by 2035, according to the Energy Department.

"Most of the places where substantial solar is getting built, you weren't farming anything. It's not like we're competing for farmland in most places, right?" said Sheldon Kimber, CEO of solar developer Intersect Power.

"Generally speaking, [agrivoltaics is] just absolutely not feasible at scale," Kimber added. "Beyond sheep and pollinators, it's just not really a thing."" [1]

1.  U.S. News: Efforts to Mix Farming and Solar Energy Grow. Brown, H Claire.  Wall Street Journal, Eastern edition; New York, N.Y.. 19 Sep 2024: A.3.