Department of Energy chief of staff surveys progress at Iowa State solar farm

Three people standing amid rows of strawberries growing beneath solar panels.
Katie Hendrickson, chief of staff of the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy, left, listens as Matt O’Neal, professor in the Department of Plant Pathology, Entomology and Microbiology and Wallace Chair for Sustainable Agriculture, center, explains the work being done at the Alliant Energy Solar Farm at Iowa State University. While O'Neal focuses on the pollinator side of the research being done, Ajay Nair, professor and chair of the Department of Horticulture, right, is studying the fruit and vegetable crops being grown at the site. Photo by Whitney Baxter

By Whitney Baxter

In the form of a juicy red strawberry, a U.S. Department of Energy representative tasted the fruits of researchers’ labor Sept. 4 at the Alliant Energy Solar Farm at Iowa State University.

The visit allowed Katie Hendrickson, chief of staff of the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy, to see the progress being made at the solar farm, which received a $1.8 million, four-year grant from the U.S. Department of Energy last year.

“To see what they’ve accomplished in such a short amount of time is amazing,” Hendrickson said of the researchers. “I appreciate how they are getting down to the granular details of the data they’re collecting to really understand it. I’m excited to see how this project progresses.”

Multidisciplinary approach to research

The project involves a collaboration among Iowa State researchers to study how well fruits, vegetables and various pollinator mixes/flowers can be grown beneath and between the rows of solar panels at the site. Beehives on the property are also being studied at the solar farm to better understand how pollinators respond to this novel habitat.

This practice of using land for agricultural and solar energy production is known as agrivoltaics.

Ajay Nair, professor and chair of the Department of Horticulture, said faculty and graduate students are investigating how the light, temperature and relative humidity conditions beneath the panels impact production of everything from broccoli and green peppers to strawberries and grapes. They are doing all of this while using the same methods and equipment that commercial producers would.

“We want to show our growers you don’t have to modify your production practices to grow fruits and vegetables near solar panels,” Nair said.

The success of the produce beneath the panels is being compared to the same produce being grown in an open area on the site, away from the panels. While it’s too early to definitively say one way is better than the other, Suzanne Slack, assistant professor of horticulture, noticed fewer Japanese beetles invading the young grape vines beneath the panels compared to those out in the open.

Matt O’Neal, professor in the Department of Plant Pathology, Entomology and Microbiology and Wallace Chair for Sustainable Agriculture, is studying the pollinator habitat and managing honey bee hives at the site. He said pollinator-friendly solar farms could be a valuable resource for honey bees and wild bees. If flowering plants can establish under and between the solar panels, there could be a source of food for bees even when soybeans and clover stop flowering. In addition to providing habitat, solar farms could make honey bees more productive and, in turn, pollinate the crops growing under the panels.

“We’re trying to create a summer-long buffet of flowers for the bees,” O’Neal said.

In addition to the plant and pollinator data being collected, Anne Kimber, director of Iowa State’s Electric Power Research Center, and her team are studying the amount of energy produced by the panels and how those levels may be impacted by the different fruits, vegetables and pollinator mixes growing beneath.

“We want to know the quality of light reflected by the various vegetation,” Kimber said.

They’re also looking at the energy production differences between fixed versus single access tracking panels – ones that follow the sun’s path throughout the day.

The final piece of the research project is determining if the agrivoltaics practices studied at this site can be replicated elsewhere. The team is exploring how landowners, utility companies and farmers can work together to generate multiple financial benefits from the same piece of land. Farmers could turn a profit from implementing an agrivoltaics operation on their land, while receiving a lease payment from the solar developer.

“One of our future questions is if consumers place more value on produce grown in an agrivoltaics system,” O’Neal said.

About the solar farm

Construction of the 1.375-megawatt solar farm was completed in fall 2023 as part of a public-private partnership between Iowa State University and Alliant Energy. Iowa State leases the land to Alliant Energy. In turn, Alliant Energy has agreed to allow Iowa State faculty and students to farm under and between the panels.

The electricity generated from the solar panels goes back on the grid to serve Alliant Energy customers, including the nearby research farms operated by the College of Agriculture and Life Sciences. The panels can produce enough electricity to power upwards of 220 households.

This project aligns with Iowa State’s five-year Strategic Plan for Sustainability Operations, which includes the goal of tripling renewable energy use.