The benefits of agrivoltaics

Picture a solar farm. You might imagine a big industrial complex replete with electrical equipment and devoid of plants and animals – especially if you’re from the Mountain West or the Desert Southwest, where such solar arrays are common.

Tall plants block sunlight and reduce the amount of power solar panels can generate. To maintain efficiency, conventional solar developers typically prepare sites for ground-mounted solar arrays by creating bare ground or planting single-seed turf that can be easily managed by mowing and spraying herbicides. But this method is to the detriment of the land, reducing water retention, soil stability and carbon sequestration, while destroying habitats for pollinators, birds and other wildlife.

Luckily, gravel and turf aren’t the only options for managing the land underneath solar panels. A new field of renewable energy research is finding ways to put the “farm” back in “solar farm.”

Agrivoltaics, as defined by the National Renewable Energy Laboratory (NREL), pair “solar with agriculture, creating energy and providing space for crops, grazing, and native habitats under and between panels.” The idea was being talked about as far back as 1982, but it has gained momentum in recent years partly due to the expansion of solar.

Although research in agrivoltaics is still in its early days, pilot projects have shown that, under the right conditions, using the land under and between solar panels for agriculture can potentially deliver numerous benefits to farmers, solar companies and pollinators.

Agrivoltaics can help crops grow

The shade provided by solar panels creates a microclimate that is cooler during the day and warmer at night, and increases soil moisture levels – conditions that can benefit some crops. Obviously not all crops are suited to these conditions. Shading and changes in the soil moisture regime may decrease yields for some crops but increase yields for others. Research shows that in some arid locations, agrivoltaics can substantially increase yields while requiring less water for irrigation.

Recent research is focused on determining what crops grow best under photovoltaic systems, how to configure solar panels for those crops, where to position crops relative to the panels, and so on. With careful planning, many crops, as well as native plants and livestock, can adapt to and thrive in agrivoltaic systems.

For example, research has shown that lettuce plants have the ability to adapt to conditions under photovoltaic systems and “compensate partially or totally [for] the reduction of light availability” through changes in leaf morphology. In Korea, researchers found that while grapes develop more slowly when grown under agrivoltaics, this can be easily addressed by delaying the harvest by just one to two weeks.

Researchers have also found that water inputs for cleaning solar panels were similar to the amounts required for agave and aloe vera cultivation, suggesting the potential for maximizing land and water use efficiency by co-locating solar generation and non-food crops in arid locations.

Agrivoltaic systems can also improve the soil quality of the marginal agricultural land upon which they’re built. As one agrivoltaic farmer from Massachusetts put it, “Every farm in this valley has a few acres that are marginal, whether it’s rocky or stony or steep, or windswept. When we take the panels down, the field will be better than when we went into it. I think there’s a place on every farm for this.”

Agrivoltaics provides pollinator habitat

Solar arrays could potentially provide important habitat for beleaguered pollinator species in dire need of it. Rather than mowing the ground beneath utility-scale solar arrays, some solar companies are using agrivoltaics to grow a carefully curated mix of native pollinator-friendly plants, creating new habitats for birds and bees, reducing pesticide use, and improving the quality of stormwater runoff.

One solar developer in the Midwest region reported that navigating the permitting process for setting up pollinator-friendly solar arrays was notably easier than for some of their conventional projects because of the added benefits of the project. The company also expects the cost of managing native plants to be lower than turf management over the long term. Site preparation for agrivoltaics commonly uses strategies like minimizing grading and accommodating existing topography. Feedback from 38 large-scale solar industry members collected by NREL found that these methods reduced civil construction costs and permitting costs and delays.

Following the establishment of standards for pollinator-friendly solar sites in Minnesota in 2016, 2,400 acres of land beneath utility-scale solar arrays were seeded with pollinator plants, equivalent to planting more than 1,800 football fields of pollinator habitat.

Additional synergistic benefits can be achieved by combining land uses in solar farms. When pollinator plants are combined with crops in agrivoltaic systems, the pollinators they attract improve crop yields. When pollinator plants are combined with grazing livestock, grazers help keep native plants short, reducing the need to mow.

Agrivoltaics may even deliver financial rewards for farmers and solar developers. Farms with agrivoltaic systems can generate their own electricity and bring in income by selling excess energy back to the grid, potentially increasing the income per unit of farmland area by 60% or more.

Thanks to research being conducted by NREL, universities and nonprofits, agrivoltaics have been successfully implemented by independent farmers interested in generating their own electricity and maximizing the productivity of their land, as well as utility-scale solar developers building large ground-mount solar arrays.

While more research is needed to understand the effects of agrivoltaics on specific crops in specific climates, the growing body of knowledge in this emerging field – knowledge available to farmers, researchers and solar developers via resources, on-site training and other forums – indicates that this innovative approach to solar energy holds significant promise for the transition to a clean energy future.

Integrating clean energy technology with our communities and reducing its impact on the environment are two of the greatest challenges we face. The promise of agrivoltaics suggests that, with creativity and hard work, we can unlock the potential of clean energy while making our lives better and protecting the environment. Plus, who wouldn’t prefer the sight of a field of wildflowers swaying in the wind, happy sheep grazing or healthy crops growing, whimsically accented by solar panels, to a barren industrial solar array?