Oregon State University study finds flowers flourish underneath solar panels

A new study by researchers at Oregon State University found that the shade from solar panels increased the number of flowers under the panels and delayed the timing of their flowering. Both outcomes could help the farming community.

Oregon State University

The study has implications for solar developers who are farming the land under solar panels, as well as agricultural and pollinator health advocates looking for land to restore pollinator habitat.

The findings, published in Scientific Reports journal, come at a time when several states such as Minnesota, North Carolina, Maryland, Vermont, and Virginia are developing nationwide guidelines and incentives to promote pollinator-oriented solar systems.

“Solar panel replacement is usually done to limit the growth of plants,” said Maggie Graham, research fellow at the Oregon State Faculty and lead author of the paper. “My thought with this research was, can we turn this around? Why not plant under solar panels that are beneficial to the surrounding ecosystem, like flowers that attract pollinators? Would insects even use it? This study shows that the answer is yes. “

Pollinating insects support the reproduction of 75% of flowering plant species and 35% of plant species worldwide. In the United States, pollination services for agriculture amount to $ 14 billion a year.

The habitat for pollinating insects is decreasing worldwide due to urbanization, intensification of agriculture and land development. Changes in the global climate can also lead to shifts in the availability of habitats. Meanwhile, solar PV in the US has grown an average of 48% per year over the past decade, and current capacity is expected to double again over the next five years, the researchers said.

The increased demand for solar modules leads to an interest in the agrivoltaic field, where solar energy production is combined with agricultural production such as growing agricultural crops or grazing animals on the same land.

Chad Higgins, associate professor in the College of Agricultural Sciences at OSU, recently published a paper that found that joint development of land for solar and agriculture could account for 20% of all electricity generation in the United States and create more than 100,000 jobs rural communities with minimal impact on crop yield with an investment of less than 1% of the annual US budget.

The new study, led by Graham, who came to Oregon after a nonprofit focused on installing solar panels for low-income families, was at the 45-acre Eagle Point solar facility in Jackson County, Oregon , carried out.

The research team collected data on pollinator and plant populations during seven two-day sampling events from June to September 2019. These corresponded to the post-bloom times for flowers. Lengthening the flowering times is important for insect pollination because they will be fed later in the season, the researchers said.

The researchers collected data from 48 plant species and 65 different insect species.

The study areas were divided into three categories: full shade plots under solar collectors, penumbra plots under solar collectors and full sun plots without solar collectors. Results include:

  • The flowering frequency was greatest in penumbra plots, in which 4% more flowers were found than in full sun and full shade plots.
  • The number of flower species and the variety of flowers did not differ between the different plots.
  • On average 3% more pollinating insects in partial shade and full sun plots than in full shade plots.
  • The number of insect species and the diversity of insects was higher in partial shade and in full sun than in full shade.
  • The number of insects per flower did not differ between the different plots.

“Unused or unused areas under solar panels provide an opportunity to amplify the expected decline in pollinator habitat,” said Graham. “In the vicinity of agricultural land, this also has the potential to benefit the surrounding agricultural community and provides a pathway for future study. Solar developers, policy makers, farming communities, and pollinator health advocates looking to maximize land use efficiency, biodiversity, and pollination services should consider pollinator habitat at photovoltaic solar sites as an option. “

Message from the OSU College of Agricultural Sciences

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