As commercial- and utility-scale solar operations have moved from niche electricity-market players to major generating resources, some utilities and developers are finding it more difficult to gain approval for new projects. Opponents argue some of these installations could do more harm than good for the local environment. Now a new approach to site management is countering that argument with plans intended to support native plant species, bees and butterflies that thrive there. Such designs are becoming standard in many states, and they could end up boosting electricity production and the pollinator populations they aim to promote.
“It’s arguably one of the fastest growing trends in utility-scale solar,” said Rob Davis, director of both the Center for Pollinators in Energy and the Media & Innovation Lab at Fresh Energy, a Minnesota-focused clean-energy advocacy group. He’s become a strong advocate for pollinator-friendly solar development, both in Minnesota and across the United States.
“East of the Rockies, it’s got great popular support and it’s really being embraced by utilities. There’s so much competition in the solar industry today that everyone’s looking for an edge,” Davis said.
Fresh Energy has been at the forefront of the national move toward incorporating native wildflowers and grasses into large-scale solar arrays. The group started investigating the practice after Minnesota passed laws in 2013 requiring its largest utility, Xcel Energy, to ramp up solar production and support new community solar projects. Soon after, farmers in the state started getting phone calls from developers seeking to lease land for new solar projects. Those farmers, in turn, reached out to Fresh Energy with concerns about the impact of taking their land out of production.
Some online research regarding biodiversity and solar farms led Davis and his colleagues to programs that were well-established in the United Kingdom. In particular, the Westmill Solar Park in Watchfield, England, caught the group’s attention. The array is said to be the world’s largest community-owned solar project, and its 30 acres are widely planted with native species.
The group also consulted with Marla Spivak, a University of Minnesota entomology professor and 2010 MacArthur Fellow whose TED talk on why bees are disappearing has been viewed more than 2.8 million times. Fresh Energy shared their projections that the Minnesota solar regulations could lead to a couple thousand acres of solar arrays going up on previously farmed land.
“She was quite direct,” noting that each additional acre of potential bee habitat is important, Davis said. “She said the reality of the situation is that the county, state and federal governments are not investing enough to keep bees alive.”
Recognizing the significance of Spivak’s concern, Fresh Energy worked to develop a coalition that included both environmental and farming groups to support legislation encouraging voluntary adoption of pollinator-friendly site-management techniques. That bill was wrapped into an omnibus agricultural package in 2016 and has influenced how utilities evaluate the plans developers submit for large-scale solar developments.
In October 2018, Xcel Energy adopted the centerpiece of the Fresh Energy model as a requirement for developers of new utility-scale and community projects in its Minnesota service territory. Now, those companies must complete a “scorecard” outlining their plans for incorporating pollinator habitat into their arrays. This point-based assessment encourages wildflower plantings over larger percentages of a project site, greater use of native plant species and ongoing management plans to maintain those species. It also discourages the use of insecticides at the site or the use of insecticide-treated seeds.
Since the passage of the Minnesota legislation, other states have begun adopting their own plans, and individual utilities have also begun exploring pollinator-friendly planning.
Davis said, beyond vegetation, developers also need to rethink how their panels are wired and mounted. Traditional array sites are often covered with gravel to keep weed growth down. In these cases, panels can be mounted 2 feet above the ground with wiring suspended in easy-to-install harness systems. Panels on pollinator-friendly sites should be at least 36 inches high for periodic mowing, Davis said. Also, it’s recommended that wiring be buried, rather than suspended, to eliminate the risk of contact with mowers.
However, Davis added, raising panels and burying the wiring are one-time costs that can end up benefiting more than bees and butterflies. For example, trading in hard-packed earth for natural meadows reduces stormwater runoff. These designs also help retain topsoil and can even improve soil health over time, including in brownfield locations.
Pollinator-friendly designs might also boost electricity production. University of Arizona researchers are looking at the possible benefits of combining agriculture and solar, a pairing called “agrivoltaics.” In a test project in the Sonoran Desert looking at growing cherry tomatoes underneath solar panels, they found that the plants produced twice as much fruit as unshaded plants while using the same amount of water. The moisture those plants transpired helped cool the panels, which boosted electricity production by about 3% during the summer months. They estimate this could average out to a 1% gain for the entire year.