Oregon State University study finds flowers flourish underneath solar panels

A new study through Oregon State University researchers found that shade provided by solar panels increases the abundance of flowers under the panels and slows the timing of their bloom, both findings that could help the farming community.

Oregon State University

The study has implications for solar energy developers who manage the land under solar panels, as well as agricultural and pollinator health advocates seeking land to restore pollinator habitats.

The findings, published in the journal Scientific Reports, are released at a time when some states, such as Minnesota, North Carolina, Maryland, Vermont, and Virginia, have developed statewide guidelines and incentives to promote pollinator-focused solar plants.

“The understudy of solar panels has mostly managed to limit plant growth,” said Maggie Graham, a faculty research assistant at Oregon State and lead author of the paper. ‘My thought in this research was: can we turn that around? Why not plant under solar panels with something beneficial to the surrounding ecosystem, such as flowers that attract pollinators? Would insects even use it? This study shows that the answer is yes. “

Pollinating insects help reproduce 75% of flowering plant species and 35% of crop species worldwide. In the United States, agricultural pollination services are estimated at $ 14 billion a year.

Habitat for pollinating insects is declining worldwide due to urbanization, agricultural intensification and land development. Changes in the global climate can also cause shifts in the availability of habitats. Meanwhile, the solar PV plant in the United States has grown an average of 48% per year over the past decade, and current capacity is expected to double again in the next five years, the researchers said.

The increased demand for solar panels is leading to interest in the field of agrivoltaics, where solar energy production is combined with agricultural production, such as planting agricultural crops or grazing animals, on the same land.

Chad Higgins, an associate professor at OSU’s College of Agricultural Sciences, who recently published a paper found co-developing land for both solar and agriculture could provide 20% of the total electricity generation in the United States, create more than 100,000 jobs in rural communities, while having 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 the state of Oregon after working for a nonprofit organization focused on installing solar panels for low-income families, was conducted at the 45-acre Eagle Point Solar Plant in Jackson County, Oregon.

The research team collected data on pollinators and plant populations during seven two-day sampling events from June to September 2019, which corresponded to post-peak bloom times for flowers. Extending bloom times is important for pollinating insects because it provides them with food later in the season, the researchers said.

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

The study locations were divided into three categories: plots with full shade under solar panels, plots for partial shade under solar panels and plots in full sun without panels. Findings included:

  • The abundance of flowers was greatest in partial shade plots, where 4% more flowers were found compared to plots in full sun and full shade.
  • The number of flower types and the diversity 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 insect diversity was higher in partial shade and full sun than in full shade.
  • The number of insects per flower did not differ between the different plots.

“Unused or underused land under solar panels offers an opportunity to increase the expected decline in pollinator habitat,” said Graham. “Close to farmland, this also has the potential to benefit the surrounding farming community and provides an avenue for future research. Solar energy developers, policymakers, agricultural communities and pollinator health advocates seeking to maximize land use efficiency, biodiversity and pollinator services should consider pollinator habitat at solar photovoltaic sites as an option. “

News release from the OSU College of Agricultural Sciences

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