Agrivoltaics is the use of land for both agriculture and solar-photovoltaic energy generation. Solar grazing is a variation where livestock graze in and around solar panels. The system looks at agriculture and solar-energy production as complementary to one another. By allowing working lands to stay working, agrivoltaic systems could help farms diversify income. Other benefits include energy resilience and a reduced carbon footprint.
December 26, 2023
Bradley Heins is an associate professor of organic-dairy management at the University of Minnesota-West Central Research and Outreach Center. He has since 2017 utilized agrivoltaics at the center’s research dairy farm. The center has a 110 head in a certified-organic system, and a 140 head in a conventional grazing system.
“We do research on pasture-based dairying and everything that surrounds dairy production here in Minnesota,” Heins said. “We got interested in agrivoltaics about 10 years ago.”
The project started by monitoring the dairy herd for energy usage. They learned exactly how much water was used and all elements of energy use on the farm.
“It’s part of a farm-wide initiative to make our entire farm carbon-neutral,” he said. “We extended our research to five other Minnesota dairy farms.”
The information gained from the energy-monitoring research allowed Heins to begin applying renewable-energy technologies – including agrivoltaics. He said the installation of solar panels into different paddocks on the farm was sometimes more common-sense than strict science. The biggest initial concern was preventing cows from damaging the panels while grazing beneath them. He hears that same concern from farmers via email at least five times each week. To determine how high to put the panels, he found the tallest cow in the dairy herd and decided how high it could reach with its tongue. He settled on an 8-foot panel height.
“Our first installation was 30 kilowatts divided in to two banks of 15 kilowatts,” Heins said. “We concreted the posts 6 feet in the ground.”
In retrospect he believes it was overkill, but said they had no idea how the cows would treat the poles that supported the panels.
“We probably built it hurricane-strength,” he said. “Other than the first few days of trying to rub on the poles and licking the panels, it hasn’t been an issue.”
That might be because the posts are steel and smooth that rubbing is less-satisfying to the cows, he said. But he recommends locating the solar inverter outside paddocks in an area inaccessible to livestock.
During hot days cows in a paddock with panels will use them for shade; he said that’s been a positive thing. In 2021 the center built a 240-kilowatt system that can provide shade for 200 to 250 cows. The poles are buried 6 feet without concrete.
But grazing paddocks are managed for grass productivity – not shade – so the herd only accesses the panels when grass is grazeable in a paddock with panels. That limited the cows to having shade about 10 days in the 2023 growing season. Managed grazing prevents mud situations and overgrazing beneath the panels. Heins said he noticed better grass recovery and growth during the dry 2023 summer beneath the panels than in the open paddocks. Orchard grass, meadow fescue and red clover seemed to do particularly well beneath the panels.
The two biggest hurdles for farmers grazing cows beneath panels are concerns about panel damage and installation cost, he said. But his five years of research shows damage is not a problem. And it increased the cost very little in 2017 to have the panels built higher. That might be different now because of the price of steel but he doesn’t think it’s a deal-breaker.
It’s important to have a plan for energy produced by solar power. The energy produced by the West Central Research and Outreach Center solar array produces power for the dairy and charges a direct-current fast charger that powers an electric vehicle used on the farm. Heins said his latest project is developing a 30-kilowatt portable solar-array shade system that moves around the paddocks. It can charge an electric tractor to pull the array.