Alliant Energy and the Iowa State University College of Agriculture and Life Sciences are partnering on a project that will research the potential for adding value to sites where solar arrays are built by planting crops in their shadow.

The idea is to see if that space beneath the panels can be used to grow high-value crops, such as tomatoes, peppers or onions, and if in return those plants can help the solar panels operate more efficiently.

The concept is known as agrivoltaics, or using solar power sites for agricultural purposes to make more efficient use of the land and create value for communities where solar arrays are located.

“We’ll be able to get down to the granular data level and see under the panels and say whether you get more energy production out of growing, let’s say, jalapenos under this panel rather than tomatoes, cucumbers or onions and be able to understand what the difference is in energy production and then what thrives in that shaded area,” said Nick Peterson, strategic partnerships manager with Alliant Energy. 

Andy Zehr, communications and recruiting and marketing director of the College of Agriculture and Life Sciences, said researchers will look at the space under the solar panels as “microclimates.”

“Part of what we’re doing is figuring out how to optimize for those particular microclimates,” he said. “We have a general sense of what we think a certain crop might produce in variable rates of shade. But it’s another thing when they’re out there in the field and based on the differences in panel installation heights and things like that to control the microclimate.”

Then there’s the “symbiotic relationship between how well those crops perform on their own to grow the food we need but how does that affect the energy production as well,” Zehr said.

“It’s the intersectionality [that] interests those researchers the most,” he said.

Solar panels don’t operate as efficiently if they get above a certain temperature, and there’s some research done in Colorado that shows having plant cover underneath helps draw that heat down, keeping the panels cooler and operating more efficiently, Peterson said.

“We want to verify that and also understand how the different crops could do it, and what level it does that here in the Midwest compared to the Southwest climates and regions,” he said.

Research will also include pollinator habitats, whether it be bees or butterflies, that are vital to helping pollinate other plants in the area.

“I think it’s very exciting to see that combination of not just your high-value crops but also the pollinator habitats and to be able to offer that diversification of education within that space,” Peterson said.

Alliant Energy and ISU came together in 2020 to discuss ways to advance their mutual goals. For Alliant it was about advancing its clean energy blueprint. For ISU it was about making progress on its sustainability goals and providing research opportunities around green energy for the College of Agriculture and Life Sciences.

“Through those talks, we found mutually beneficial options to create the Alliant Energy Solar Farm at Iowa State University, and throughout the entire way we’ve been collaborating as one unit to make sure that everything that happens with this project is mutually beneficial for both entities to succeed,” Peterson said.

The project is funded by a $1.8 million grant awarded to ISU by the U.S. Department of Energy. It is for four years with a goal of providing a better understanding of how things grow in the Midwest. Alliant Energy’s investment covered the match that was required for Iowa State to receive the grant.

The solar array will produce 1.35 megawatts of energy and sit on about 10 acres south of Ames.

Construction of the array is planned to begin April 3, with completion expected in the fall. The first full growing season and research is planned for 2024, Peterson said.

Alliant Energy will own the solar panels and related equipment and lease the land from Iowa State University.

The research team is led by Ajay Nair, an associate professor of horticulture; Matt O’Neal, a professor in plant pathology, entomology and microbiology; and Electric Power Research Center Director Anne Kimber.

Peterson said the goal is to show how land values at solar arrays can be maximized.

“So you’re getting a kind of double dip of the land that’s there in terms of what it can be used for,” he said. “It’s not just for energy production. It allows for both operations in the same space.”