Matthew Gorrie / Bolton Bees
Minnesota will be included in a study to help federal researchers test the potential of pollinator-friendly habitat and fruit and vegetable crops around solar arrays.
The National Renewable Energy Laboratory (NREL) will plant vegetation this year at three Minnesota solar installations owned by Enel Green Power. The sites are among 15 around the country that will be part of the research project.
“We want to figure out what plants and what type of species will thrive, and how, and why, in these environments,” said Jordan Macknick, an NREL analyst. The plants can provide economic and environmental benefits over covering the ground with gravel or turf grass, as is often done.
The stakes for both the industry and environment will only grow as the amount of land used for solar projects also expands. NREL predicts 3 million acres will be devoted to solar farms by 2030, and 6 million by 2050.
In Minnesota, researchers will test vegetation on three 1-acre plots within Enel’s 100-megawatt Aurora project, which includes installations at several locations in the state. A third of each plot will be devoted to prairie plants and grasses. Another third will contain pollinator-friendly habitat. And the remaining third will feature a mix of agricultural crops.
Minnesota is already a leader in pollinator-friendly solar, having passed a 2016 law that encourages developers to follow siting guidelines and incorporate native grasses and wildflowers. Fresh Energy, which publishes Midwest Energy News, was involved in advocating for the pollinator-friendly solar legislation.
“There’s been a lot of exciting things happening in Minnesota and I feel we’re ahead of the game,” said Megan Benage, a regional ecologist with the Minnesota Department of Natural Resources.
The idea of growing crops among solar installations is newer but not unprecedented. Macknick said researchers in other states have grown beans, kale, melon, squash, lettuce, peppers and broccoli under or near solar panels. Crops could be harvested by hand or by smaller farm equipment, he said.
Minnesota’s solar pollinator standard is voluntary, but state utility regulators require pollinator-friendly vegetation at developments larger than 50 megawatts. As a result, half of the state’s 4,000 acres of solar farms have pollinator habitats, Benage said. A commercial beekeeping company, Bolton Bees, even operates on a solar garden near the Twin Cities and sells a line of products called “solar honey.”
NREL’s research project, known as Innovative Site Preparation and Impact Reductions on the Environment (InSPIRE), might reveal new opportunities to add value at solar farms. It could also help make the case that vegetation can lower the cost of developing and maintaining solar projects, Macknick said.
Site preparation accounts for about 20 percent of the cost of solar projects, Macknick said. Developers typically clear all vegetation before leveling the site and putting down gravel or turf prior to panel installation. Leaving existing vegetation in place could reduce the cost of land clearing, soil compaction, stormwater management and herbicide spraying.
“We tell developers if they vegetate the site it will be easier for them to manage in the long term,” Benage said. “The neighbors like it more because the site is showier, with more flowers and more interest than a mowed lawn – unless you’re a fan of mowed lawns.”
And the right vegetation can even improve production of solar panels by lowering the temperature.
“Having vegetation underneath the panels reduces the temperature of the panels,” Macknick said. “Panels with cooler temperatures have increased solar output.”
Travis Bolton, of Bolton Bees, points out that better environments will result in more resilient bees. In Minnesota, which lost half its bee population a couple of years ago, that’s an important virtue.
Any effort to create pollinator-friendly habitat is welcome, said Minnesota’s best-known bee advocate, MacArthur Foundation Fellow and University of Minnesota Distinguished McKnight Prof. Marla Spivak.
“These plantings can be great for bees,” Spivak wrote in an email. “If diverse, native flowers are planted, they are great for native bees, and somewhat helpful for honey bees. If cover crops with legumes are planted, they are great for honey bees and somewhat for native bees.”