Can Solar Farms Save the Bees?
Here's how solar panels can make space for pollinators, just when we need more of both.
Milkweed -- food for this monarch caterpillar -- growing near solar panels.
Solar farms can grow more than just clean energy. They can be a cradle for a struggling but essential population: pollinators.
To avoid the worst effects of climate change, we need to stop burning the fossil fuels that are warming the planet and rapidly transition to carbon-free forms of energy like solar, wind and geothermal.
Meanwhile, climate change, along with habitat loss and pesticide use, is causing populations of pollinator insects to crash, imperiling plant life, including some plants humans use for food. Some estimates put the rate of decline at about 2% per year or 45% over the last 40 years.
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There's hope that efforts to solve one problem might help with the other: Recent research by scientists at the Argonne National Laboratory found that the conscious design of solar farms can help reverse the decline of pollinators. In Minnesota, two solar sites planted with native plants had their pollinator populations triple in just four years.
The results "tell us that it is achievable and you can see pretty quick results at the solar sites within four years or so," said Lee Walston, an ecologist at Argonne National Laboratory and an author of the published research.
The problem for pollinators
Insect pollinators (not all pollinators are insects) are on the decline for several reasons, including climate change. Pesticides used to kill pest insects can also kill beneficial ones. Land development that turns suitable habitats into roads, lawns, parking lots and buildings reduces the food and habitat available to insects. At the same time, invasive species outcompete native species and new diseases reduce populations further.
As the climate changes thanks largely to emissions from burning fossil fuels, plants some insects rely on may bloom too early or shift their range in search of cooler temperatures, leaving the insects without a food source and the plant without a pollinator.
About one out of every 10 species of bee and butterfly in Europe are threatened with extinction, according to the European Union. The number of bumblebees in the United States has decreased by 50% since 1974, according to the US Fish and Wildlife Service. Even in some relatively undisturbed forests, US Forest Service scientists found that the number of bees and butterflies declined by 60% over 15 years.
Problems for pollinators could translate into problems for people, too. Research published in 2022 found that declining populations of pollinators and the resulting decline in crop production could contribute to more than 400,000 premature deaths each year. Pollinators add billions of dollars to the economy each year.
How solar farms can make room for pollinators
The two solar installations the Argonne scientists studied were formerly working farmlands that were then filled with solar panels and native plants. Pollinators came flooding back with the reappearance of plants that provide habitat and food.
Over the study both the number and type of flowering plants and insects increased, with some types more than tripling. There were twenty times more native bees present at the solar installations at the end of the four years.
In 2024, these aren't new results, but they match the findings of other studies.
"We saw that within these other studies there were pretty rapid responses. Within five years you noticed a big increase in that plant community and a big increase in the pollinator community," Walston said. "Our results sort of fit in with that."
That timeline is likely to vary based on region. While five years fits a typical timeline for the region, hotter, drier areas might take longer, Walston said.
Solar farms on farmland
Large-scale solar installations on agricultural land have been something of a flashpoint recently, with local opposition stopping individual projects or barring such developments wholesale. It's a challenge that makes achieving climate goals more difficult.
Solar installations may require 10 million acres, or 0.5% of the country's surface area by 2050, according to a 2021 report from the US Department of Energy. The same report says disturbed lands (a category that includes developed areas and areas impacted by invasive species) make up 8% of the contiguous 48 state's surface area, while agricultural land makes up 43%. Paved and urban areas (that include a lot of rooftops) make up another 5%.
Solar panels surrounded by native plants are good for pollinators.
Solar developers increasingly need to grapple with local opposition to solar development, but the researchers in this study found a beneficial spillover effect from solar and native plant sites.
"We also see increased pollinator visits to adjacent farmland," Walston said. "The solar sites could provide habitat that could increase the pollination service to adjacent farmland."
Surrounding solar panels with plants can make solar panels more productive, too. Vegetation creates a cooler microclimate around solar panels, compared to bare ground or pavement. Solar panels are more efficient when they're cool.
With just minimal maintenance requirements -- mowing and limited herbicide use -- the solar-with-native-plants model is one way to install solar panels that not only avoids harming biodiversity but also helps it.
"There's a lot of opportunity to provide a net benefit with habitat enhancement at these sites," Walston said.
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