Can solar and farming work together to fight climate change in Southern California?

Can solar panels over farm fields help us adapt to and fight climate change at the same time? That’s what a new study breaking ground next month will explore.

“This study is about agriculture and climate change and how we can create kind of a win-win,” said Susan Phillips, director of the Robert Redford Conservancy at Pitzer College, which is leading the study.

The concept is called “agrivoltaics,” a combination of the words “agriculture” and “photovoltaics” — the process of converting light into electricity.

There are multiple ways to do agrivoltaics, but the basic idea is that instead of stopping farming to make way for solar, elevated solar panels are installed over crops or livestock operations so electricity generation and farming can happen at the same time, and possibly benefit each other.

Different types of agrivoltaics

(

Courtesy National Renewable Energy Lab

)

While agrivoltaics have been studied in other parts of California, this will be the first study to see how it could work in Southern California. Agrivoltaics have been successful in parts of Europe, China, as well as the U.S., but it’s not happening much here in California…at least not yet.

How the study will work

The study will take place on a quarter-acre of land at Spadra Farm at Cal Poly Pomona. Researchers will study how a plot of romaine lettuce grown under the panels fares compared to a plot that is not, over a period of three years. They’ll also have a mobile battery to store the solar energy.

They’ll measure things like soil fungus and bacteria, plant nutrients, crop yield, water use, temperature and more.

“This is all going to be very relevant to the production of a crop in Southern California, primarily romaine lettuce, which is something that is in demand all year round,” said Rose Olivas, one of the project’s leads.

A key question they aim to answer is how much shade from the panels can lessen water use and improve plant and soil health amid hotter summers driven by climate change.

“We're living in a time of climate crisis, and our seasons for growing are becoming increasingly limited, especially for cold weather crops like romaine lettuce,” said Emily Kuhn, who will be managing the farm during the study. “So part of the goal of this project is to be able to produce crops like romaine lettuce for longer periods of time in the summertime as that stretches longer.”

They’ll start installing the solar panels in December and expect to start planting in January.

What’s the benefit?

Agrivoltaics is happening already, primarily in Europe and China. Research across the world and parts of the U.S. has already found that the strategy can help reduce water use, improve soil health and boost crop yields. It can work with livestock grazing, a variety of crops as well as cover crops that provide habitat for native pollinators. Most agrivoltaics in the U.S. are currently on the east coast and upper Midwest.

The benefits are largely a result of the shade the panels provide. Amid increasingly extreme heat, the shade from the panels can cool plants and livestock, helping with soil health, water retention, and crop yield. The shade can also help alleviate heat illness among farmworkers. And the plants underneath the panels can cool the solar panels themselves, making them more productive.

At the same time, as water supplies diminish due to climate change and overuse, farmers are already, and will need to continue, to take a lot of land out of production. The American Farmland Trust, which is a partner on this study, estimates 83% of new solar development built in the next few decades will likely be on farmland.

So adding solar production to the mix can keep more land in production while potentially boosting yields with less water to go around. Farms can benefit financially by saving on their energy bills or selling the power they generate back to the grid, if the transmission infrastructure is there and their solar array is large enough for that to be economical.

Phillips said she also sees agrivoltaics as a way to improve local economies.

“We need to diversify our economy in places like the Inland Empire, and we need to think about what it means to try to maintain the agricultural land that we have,” Phillips said. “Marrying that with the production of energy is a really interesting solution.”

Not a silver bullet

Agrivoltaics are a promising piece of the puzzle when it comes to addressing our energy needs, climate pollution and the many challenges farmers are facing, but it’s no silver bullet.

These projects are generally more expensive than traditional solar arrays, technically challenging to design and difficult to permit, and they’re not easily scaled up, said Jon Reiter, a farmer and solar developer in the San Joaquin Valley. He believes that agrivoltaics is limited in California.

The current state of agrivoltaics in the U.S. Most systems are over pollinator and other native habitat.

(

National Renewable Energy Laboratory

/

LAist

)

“We don't have a shortage of land, we have a shortage of water,” Reiter said. “If you raise the panels, that's going to have an increased cost for the additional steel…the net result is that the power costs are going to be higher.”

He said he can see agrivoltaics being most realistic over cover crops that serve pollinators, as well as in more urban areas or areas that don’t have as much space for solar and farming (such as in Massachusetts, which is leading efforts in agrivoltaics in the U.S.). University of California researchers, as well as the Department of Energy's National Renewable Energy Lab, are working on the challenge of cost and scalability.

Reiter said going the agrivoltaics route will depend on the specifics of each farm. He farms almonds, pistachios, raisins, and blueberries. He said even with crops like blueberries where he could theoretically use agrivoltaics, it doesn’t make sense because he now mostly harvests by machine.

“Labor costs in California are so high that hand harvest crops are under threat because it becomes unaffordable,” Reiter said. “I farm blueberries and we used to handpick, but now we're 100% machine harvest.”

Spacing the panels to make room for those machines wouldn't be cost-effective, he said.

When it comes to meeting clean energy needs, Reiter said California has the space to do it and developing more utility-scale solar on already-disturbed agricultural lands can help lessen development of solar on sensitive desert habitats.

Bottom line — solar and farming don’t have to be at odds, Reiter said, but like any climate solution, there’s no one-size-fits-all approach.