Solar Developers: Now Hiring Pollinators

April 17, 2023

Above; RIP Cartoonist Edward Koren.

National Renewable Energy Lab:

On a humid, overcast day in central Minnesota, a dozen researchers crouch in the grass between rows of photovoltaic (PV) solar panels. Only their bright yellow hard hats are clearly visible above the tall, nearly overgrown prairie grasses—which are growing exactly as expected.

Bent over white, square frames, some of the researchers catalog the number and type of native plants growing on a square foot of land. Others press double-forked meters into the ground, measuring the soil moisture below the solar panels and in open ground. Nearby, beekeepers check on the health of local hives.

Their research is part of an ongoing study to quantify the benefits of a new approach to solar installations: low-impact solar development.
With low-impact solar development, the ground may also be leveled in some places, but the topsoil is preserved. After the panels are installed, native and other beneficial vegetation—often friendly to bees and other pollinators—is planted.

The deep roots of native vegetation retain more water than turf grass and gravel during heavy storms and periods of drought. They also help retain topsoil and improve soil health over time, even in “brownfield” areas with polluted soils.

Perhaps most importantly, native and flowering vegetation provides a habitat for native species, especially pollinators and other beneficial insects that can improve yields at nearby farms.

“One surprising thing is how rapidly and significantly pollinator-friendly solar has taken off in the states,” said Jordan Macknick, NREL’s lead energy-water-land analyst and principal investigator for the InSPIRE project. “Every state we work with wants more information on pollinator-friendly solar.”

At several InSPIRE sites, local beekeepers and university and national laboratory researchers are tracking their bees’ visits to the pollinator-friendly vegetation under the solar panels. The goal is to determine how vegetation at solar sites can benefit insect populations and to understand the extent to which pollinator-friendly solar installations can boost crop yields at surrounding farms.

The low-impact approach also benefits solar developers. For example, skipping the removal of topsoil reduces site preparation expenses. As prices continue to fall for solar panels and other hardware, nonhardware costs (including site preparation) will soon account for 20% of total utility-scale solar costs. Native vegetation, if selected appropriately, also requires less ongoing maintenance than traditional gravel or turf grass approaches, as there is less of a need for mowing or spraying.

Flourishing vegetation can even boost energy production from solar panels. Warmer temperatures can reduce the efficiency with which PV cells convert sunlight into electricity. The ground shading and increased evaporation provided by a healthy layer of undergrowth can actually cool solar panels, increasing their energy output.

What was once experimental is now considered standard best-practice by the leading solar developers in the Midwest – see below.


2 Responses to “Solar Developers: Now Hiring Pollinators”

  1. rhymeswithgoalie Says:

    Sample image from the NREL article (plants preferring the partial shade):

  2. rhymeswithgoalie Says:

    Native vegetation, if selected appropriately, also requires less ongoing maintenance than traditional gravel or turf grass approaches, as there is less of a need for mowing or spraying.

    I like the idea of putting grazers in with solar panels, who’d have the opportunity for shade during hot days. (In part because of seeing my grandfather’s Black Angus out in the treeless pastures during the summer.)

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