Amid the steady growth in solar power generation in the United States, conserving pollinators in solar installations has become an attractive sideline, but the long-term success of these efforts remains to be seen. Can the land of a solar farm become a real resource for pollinating insects? Will solar developers see value in the additional investment to plant and maintain flowering vegetation?

A group of entomologists address these questions in a new article published today in the journal Environmental entomology. They say the association of solar energy with pollinator habitat holds great promise, but scientific evaluation and meaningful standards will be essential to make it a true win-win combination.

Already, eight states have passed laws to promote pollinator-friendly solar development (Illinois, Maryland, Michigan, Minnesota, Missouri, New York, South Carolina, and Vermont), all of which include dashboards that outline the criteria that a solar installation must fulfill to earn a “pollinator-friendly” designation. Details vary, but the basic requirements are similar from state to state, following well-established principles for the habitat that will attract and support bees, butterflies, and other pollinating insects.

“If you stick to the principles of native, perennial, and flowering vegetation and think of a mix of species that would bloom throughout the growing season, that’s more than half the battle,” says Matthew O ‘Neal, Ph.D., professor of entomology at Iowa State University and co-author of the article with Adam Dolezal, Ph.D., assistant professor of entomology at the University of Illinois at Urbana- Champaign, and Jacob Torres, doctoral student in Dolezal’s laboratory at UIUC.

O’Neal and his colleagues agree with the scorecard approach, but say the criteria should be both stringent enough to produce measurable positive impacts on pollinators, but flexible enough to be achievable under the unique conditions of a solar farm.

“You can say, how is this different from a hundred other conservation practices? ”, Says Dolezal. “And the answer is, well, there are some very weird and specific requirements to get this even on the table for solar developers to consider. And this is something that we are still learning.

On a typical solar farm, the areas under the solar panels, immediately adjacent to them, and around the perimeter of the farm each allow for different mixes of plants. Some solar panels, for example, can stand just 18 inches off the ground, which would exclude tall grasses and non-shade tolerant plants below.

If the right mix of plants can be found, however, solar developers could earn more than just positive, green public relations for their utilities. Some preliminary research suggests that surrounding vegetation may increase the efficiency of solar panels, but more analysis is needed. “We know that plants, through respiration, cool the air around them, and we know that when solar panels are kept cool, they are more efficient at generating electricity,” explains Dolezal. “What has not been shown is that, in these large-scale real-world installations, does this actually provide a significant benefit that can then be quantified, built into an economic analysis that developers can look at it and say, “We’re going to make X more megawatts of energy over how long.”

Eight states in the United States have enacted laws to promote pollinator-friendly solar development, all of which include dashboards outlining the criteria a solar installation must meet to achieve a “pollinator-friendly” designation. Details vary, but the basic requirements are similar from state to state, following well-established principles for the habitat that will attract and support bees, butterflies, and other pollinating insects. We note here the criteria included in the Illinois dashboard, with an artistic rendering of a solar development in an agricultural landscape. The colors designate the different components of the terrain to which the scorecard refers. (Image originally published in Dolezal et al 2021, Environmental entomology)

A solar farm pollinator habitat dashboard is also just a first step. Many plants recommended for pollinator conservation take time to establish and require special attention to remove unwanted and non-native plants. Thus, Dolezal, Torres and O’Neal recommend that the standards also be associated with periodic evaluations by independent and certified third parties. “These environments are dynamic,” says O’Neal. “You want to make sure that these factories are established and that you meet the goals that you set out to begin with. “

Other key elements for conserving pollinators on solar farms would include detailed maintenance and cultivation plans, clarity on whether to focus on wild pollinators or managed honey bees, and cooperation with communities. local.

“What may be true or what may work well in Iowa, Illinois, and Indiana may not work in the Southeast, or it may not work in the Mid-Atlantic Coast,” Dolezal says. . “The realities are going to be different there. “

Research has shown that even small patches of natural habitat in otherwise cleared or managed areas can provide important resources for the conservation of plant and animal biodiversity. O’Neal and his colleagues note examples of solar installations planned in some states of several thousand acres. “If even a fraction of the land allocated for future development can be planted with effective habitat for pollinators, these contributions could be substantial,” they write.

As more solar energy developments take shape, researchers will have the opportunity to begin to measure how effective companion pollinator habitat can be. Dolezal will be among them, as he works on a project selected for funding by the Solar Technologies Office of the US Department of Energy and managed by the University of Illinois at Chicago. It will help assess the ecological benefits, solar production performance benefits and economic impacts of pollinator plantations in six solar installations.

It’s a framework Dolezal says he never envisioned when he first began studying entomology, and which talks about the unique combination of solar power and pollinator conservation.

“It wouldn’t have been a habitat implementation mechanism that I would expect, for sure,” he says. “And I never would have expected to have to do pollinator sampling while wearing a hard hat.”

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