Argonne Study Shows Insect Populations Flourish in the Restored Habitats of Solar Energy Facilities

With global insect biodiversity in decline due to habitat loss, pesticides, and climate change, the restoration of insect habitat paired with smart land use changes toward renewable energy developments could help reverse the course.

Researchers at the U.S. Department of Energy's (DOE) Argonne National Laboratory and the National Renewable Energy Laboratory wanted to understand the ecological value of photovoltaic solar energy sites planted with native grasses and wildflowers. The five-year field study looked at two solar sites in southern Minnesota operated by Enel Green Power North America. Both sites were built on retired agricultural land. They examined how vegetation would establish and how insect communities would respond to the newly established habitat.

Agrivoltaics is the combination of solar energy production with agricultural and vegetation management practices. One type of agrivoltaics focuses on the establishment of habitat for insect pollinators and other wildlife that can provide important ecosystem services, such as pollination. To date, however, there has been little field data available to document the feasibility and the ecological benefits of this novel land use approach.

The two solar sites were planted with native grasses and flowering plants in early 2018. From August 2018 through August 2022, the researchers conducted 358 observational surveys for flowering vegetation and insect communities. They evaluated changes in plant and insect abundance and diversity with each visit.

By the end of the field campaign, the team observed increases for all habitat and biodiversity metrics. There was an increase in native plant species diversity and flower abundance. In addition, the team observed increases in the abundance and diversity of native insect pollinators and agriculturally beneficial insects. Flowers and flowering plant species increased as well. Total insect abundance tripled, while native bees showed a 20-fold increase in numbers.

In an added benefit, the researchers found that pollinators from the solar sites also visited soybean flowers in adjacent crop fields, providing additional pollination services.

The research findings suggest two important implications of habitat-friendly solar energy. One is that habitat-friendly solar sites can play an important role in conserving biodiversity. Second, habitat-friendly solar sites can help mitigate land-use conflicts associated with the conversion of farmland for solar energy production.

Overall, additional research is needed to understand the feasibility of habitat-friendly solar across different regions and to meet different ecological goals such as conserving a target insect or wildlife species.