DCE Solar's Fixed-Tilt Racking Adjusts to a Field Full of Broccoli, Bees, and Research Questions

Ames, IA: Most racking systems only have to worry about the sun. The one at Iowa State University's new agrivoltaics site also has to clear a tractor, avoid shading a raspberry bed, and leave room for a beekeeper. DCE Solar supplied the fixed-tilt portion of that racking, and its ability to bend to the researchers' agenda rather than the other way around is a big part of why the site works at all.

The 1.375 MW solar farm sits on 10 acres of ISU property near Ames, developed by Alliant Energy under its Customer-Hosted Renewables program and funded in part by a $1.8 million U.S. Department of Energy grant, the largest ever approved under that program. It is the first agrivoltaics research site in the Midwest, and the goal is straightforward if ambitious: figure out whether solar power generation and cash crop farming can share the same acre.

A Racking System That Had to Answer to Agronomists, Not Just Engineers

The site runs a mixed racking configuration, 60 percent single-axis trackers and 40 percent fixed-tilt from DCE Solar. The fixed-tilt sections carry the added burden of accommodating an active research farm underneath them, which meant standard racking heights were never going to cut it.

• Four different array heights on one site. Portions of the racking were installed between 5 feet and 8 feet off the ground, giving researchers room to run farm equipment and plant varying crop types underneath and around the array.

• Wiring routed around the farming, not through it. Electrical infrastructure was positioned so it would not interfere with, or be damaged by, tractors and gardening equipment operating on the site.

• Flexibility without giving up structural discipline. Fixed-tilt racking had to hold that variable-height configuration reliably across the full array footprint, not just in a single test row.

Ajay Nair, ISU's Professor of Horticulture and lead principal investigator on the project, credited Alliant Energy for its willingness to adjust the array design for agrivoltaics. That willingness only becomes a working solar farm when the racking hardware underneath it can actually execute the plan, which is where DCE Solar's fixed-tilt system did its job.

Why the Height Variability Matters

ISU's research plan calls for planting broccoli, summer squash, peppers, strawberries, and raspberries in sunny and shady micro-sites within the array, then comparing their performance against an open-field control plot. Some of that comparison depends entirely on panel height and shade pattern, which is a variable DCE Solar's racking configuration made possible to test in the first place.

"One of the things that we want to answer is what is the yield when we grow crops between and under the solar panels," Nair says. "What are the differences between open-field and agrivoltaic systems, are there more diseases, are there more insects, and so on?"

Beekeeping is part of the plan too. Undergraduate students will raise bees for honey production and pollination inside the array's fence line over the four-year study.

A Living Laboratory, Not Just a Power Plant

The array is projected to power about 200 homes and provide ISU with an annual lease payment plus renewable energy credits under a 20-year agreement with Alliant Energy. But its real output, at least for the next four years, is data. Nick Peterson, Strategic Partnerships Manager at Alliant Energy, calls the site "a teaching asset" for the university, one built through what he describes as "a real collaboration in the solar array design."

The Takeaway for DCE Solar

Agrivoltaics research sites do not have the luxury of a one-size racking template. ISU's site needed fixed-tilt hardware that could hold four different heights across a working farm, protect wiring from equipment traffic, and stay structurally sound while researchers ran experiments underneath it for years at a time. That is a materially different brief than a standard array, and it is the brief DCE Solar's fixed-tilt racking was built to answer.

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**Sources:**

Kryzanowski, Tony. ["Iowa agrivoltaics—growing broccoli, beekeeping and solar panels."](https://www.altenerg.com/back_issues/story.php?sid=3167) *enerG Magazine*, Q1 2024.