Hundreds of sheep helping keep prairie plants in check at Xcel’s Sherco solar project

At Xcel Energy’s Sherco Solar project near Becker, thousands of solar panels stretch across a field of native plants and flowers.

If those plants grow too tall, they could block the sun and keep the panels from producing full power. So the vegetation needs regular trimming.

Xcel is getting help from an unusual labor source: hundreds and soon thousands of sheep, which graze beneath the solar panels and keep the vegetation tidy.

Last week, a truck pulling a trailer bumped down a gravel road past endless rows of solar arrays. A crew jumped out and attached a metal ramp to the back of the trailer, then opened the gate. Hundreds of sheep and lambs clambered down the ramp, spread out into the field and started munching beneath the solar panels.

“By the end of the project, there will be several thousand sheep out here,” said Briana Beck, project supervisor for Minnesota Native Landscapes or MNL, an ecological restoration company based in Otsego. 

MNL is contracting with Xcel Energy to provide the sheep grazing at Sherco Solar, Minnesota’s largest solar energy farm near Becker, which started producing power last fall. 

Xcel is building this massive solar project to replace some of the electricity generated by the nearby Sherco coal-fired power plant, which it’s retiring by 2030. Eventually, Sherco Solar will have 1.6 million solar panels and will generate enough electricity to power about 150,000 homes.

These days, most large solar projects have pollinator habitat planted underneath the panels. The native plants and flowers support bees and butterflies.

Sheep are a cost- and time-saving way to manage vegetation and keep the plants from growing over the solar panels, said Luke Molus, operations manager for Sherco Solar.

“They graze all day long,” he said. “If you had someone come out here to actually cut the grass and mow it down, it does take a lot longer and is a little more expensive.”

So far, the sheep are doing a “fantastic” job, Molus said.

“The (vegetation) is getting trimmed down to what we need, and it's looking great,” he said. 

Grazing animals on a solar farm is an example of agrivoltaics, a growing practice of pairing renewable energy with agriculture that provides mutual benefits. 

More than 113,000 sheep grazed 129,000 acres of solar farms last year, according to the American Solar Grazing Association. That included 500 sites in 33 states.

Minnesota Native Landscapes has sheep grazing on about 50 solar farms in Minnesota, plus others in Ohio, Illinois, Michigan and Wisconsin. 

MNL owner Joe Schaffer said he expects the demand for solar sheep to grow. The U.S. needs about 10 million acres of solar panels in the coming decades to meet the nation's net-zero carbon goal. 

“Almost all has vegetation or forage growing on it, and it's always going to be fenced in,” Schaffer said. “So they’re super perfect for grazing large quantities of sheep.”

Beck said sheep are ideal to manage a restored native prairie, which bison grazed long ago.

“Obviously, you cannot bring bison into a solar field. They’re a little bit too big,” she said.

But sheep are small enough to graze underneath the solar panels. They forage on a variety of plants, and they can get into cracks and crevices that are tough for a mower to reach, Beck said.

“They can get in those small spaces where you'd have to do hand trimming,” she said. “They're physically removing the vegetation, which means there's less thatch buildup. And the thatch buildup can be a fire risk, which is a big concern on solar.”

Sheep’s hooves aerate the soil, and their manure acts as a natural fertilizer — all contributing to a healthier prairie, Beck said.

“If you improve the soil, then you’ll have healthier, more diverse habitats, which supports more pollinators,” she said.

Bees and butterflies help neighboring farmers by pollinating their crops. MNL also partners with local producers to give them access to solar farms to graze their animals, Beck said.

“That helps a lot with acceptance in the local community, if (farmers) can see the benefits directly to them,” she said.

Research studies also have found that solar grazing can lead to happier and healthier animals, who prefer the shade provided by the solar panels.

When it’s complete, Sherco Solar will cover almost 5,000 acres of former potato fields, and will be one of the largest restored prairies in Minnesota. The sheep are expected to be around for a long time to keep it in shape, Schaffer said.

“As the site grows, so too will the flock,” he said.