As the cost of solar panels has gone down, the benefits of installing them has gone up. But one potentially overlooked benefit comes from what happens below the panels. Some farmers and solar panel developers are growing pollinator plants in the shade cast by the panels. But until recently researchers hadn’t confirmed if cover from the sun was helping cultivate pollinator habitat or not.
A new study in Scientific Reports shows how some shade can be a good thing by increasing floral abundance and delaying blooms, offering the often hard-to-find food source for late foragers and pollinators in drier areas. “After working in both the ecological restoration and solar energy sectors, I wondered why more people weren’t planting solar with native plants or with pollinator habitat,” says lead author Maggie Graham. “It turns out there was very little data on how solar [hardware] affects pollinators and flowering plants, so I wanted to help change that by documenting the relationships.”
The researchers focused their study on an 18-hectare plot in southwest Oregon on the traditional land of the Takelma peoples. Two years before researchers collected data, the site was converted to a commercial solar generation facility. In an effort to cultivate pollinator habitat, including for bees from a nearby apiary, the facility owners restored the site with native plants and removed invasive ones.
To understand how the solar panel shading would affect floral resources for pollinators, the research team observed pollinators and their plants in areas that were either in full sun near panels, always shaded by panels or—due to automated tilting—shaded for part of the day. They noted the abundance and diversity of plants and floral blooms as well as the number and types of pollinators that visited each site type from June to September.
The team found that partially shaded areas harbored four percent more blooms than both fully shaded and full sun areas, but floral diversity and richness were similar in all site types. Partially shaded areas also had more blooms later in the season. In terms of insects, the team found that pollinators didn’t mind foraging in a little shade: three percent more pollinating insects visited full sun and partially shaded areas compared to fully shaded ones.
Though the types of plants that may be affected by shade may change in different climates, the authors conclude the general trend demonstrated in the work will likely hold true: solar panel shading can change floral abundance and timing without affecting the number of pollinator visitors.
The work demonstrates the opportunity solar panels offer through creating favorable microclimates to support pollinator communities.
Source: Graham, M. et al. Partial shading by solar panels delays bloom, increases floral abundance during the late‑season for pollinators in a dryland, agrivoltaic ecosystem. Scientific Reports, 2021.
Image: Maggie Graham
