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Agrivoltaics: Combining Agriculture And Solar Installations

According to the American Farmland Trust, the U.S. lost 2,000 acres of farmland and ranchland daily from 2001 to 2016. If this trend continues, the U.S. will lose an area almost the size of South Carolina between 2016 and 2040. The loss of prime agricultural land could be detrimental to food security. Although numerous factors are driving this trend, solar farm construction is contributing to some agricultural land loss.

Is it necessary to choose between food and renewable energy production? We may not have to choose in the future. Some solar energy developers and researchers are experimenting with agrivoltaics, simultaneously incorporating solar panels and agricultural production on the same plot of land. This can boost the sustainability of photovoltaic systems with agrisolar, while mitigating fossil fuel use and climate change.

"Solar projects are commonly built on agricultural lands, which then creates the challenge of balancing food security with increasing renewable energy production," says Brittany Staie, a research intern at the National Renewable Energy Laboratory. "Agrivoltaics gives us the opportunity to explore growing food while also producing clean electricity on the same piece of land."

What Is Agrivoltaics?

Agrivoltaics combines solar energy production and agriculture. It can entail growing crops, locating honeybee hives, and grazing livestock at ground-mounted solar farms. In some cases, solar developers alter the layout of the solar farm by elevating the panels or allowing larger row spacing to enable livestock grazing and farm equipment access. However, such modifications can increase the construction costs of solar PV farms, so it is critical to understand how to make agrivoltaics cost-effective and practical on a larger scale.

One of the most widespread uses of agrivoltaics involves grazing sheep on solar farms. This also helps reduce the need to mow the site to prevent vegetation from shading the PV modules and usually doesn’t require modifications to the project layout. In addition, some solar developers are partnering with beekeepers to locate honeybee hives at solar farms. However, it is currently relatively rare to cultivate crops at solar farms.

The National Renewable Energy Laboratory InSPIRE Program is investigating how to make agrivoltaic systems more widespread. "Through our work, which spans multiple regions, configurations, and agricultural activities, we've seen so many initial promising results," says Jordan Macknick, NREL's lead energy-water-land analyst and principal investigator for the InSPIRE project. "Now, our challenge is to figure out how to scale up and replicate these successes."

What Are The Benefits Of Combining Agriculture And Solar Energy?

Some communities are hesitant about solar farm development. Some concerns include the loss of productive farmland and the impact solar farms have on soil quality. Integrating food and sustainable energy production can help mitigate these concerns, boosting support for solar developments that incorporate agrivoltaics.

In addition, food production creates economic opportunities for local farmers, beekeepers, and ranchers. One reason sheep grazing is becoming more widespread is that it can reduce mowing costs and decrease the use of herbicides while preventing shading on the photovoltaic panels, so it is a win-win arrangement for solar developers and farmers alike.

Because agrivoltaics is a new approach, research is needed to establish best practices and make it cost-effective on a large scale. Therefore, some agrivoltaic projects establish relationships within the research community, creating hands-on learning opportunities about crop productivity, soil health, and how solar panels create micro-climates.

Potential Drawbacks Of Dual-Purpose Land Use

It can be challenging for farmers to use agricultural equipment when there are PV panels and racking systems on the land. Elevating the panels or allowing larger spacing between rows could make the plot easier to farm, but not without disadvantages. These modifications can increase construction costs or require more land.

Agricultural production usually requires having water available for livestock and irrigation, which is challenging on some sites. Not all land is well suited for agricultural production, especially in arid regions in the Western U.S, so dual purpose land use may not be applicable. Also, solar energy systems can shade crops, so proper crop selection is important, as some crops are better suited for partial shade.

Constructing solar arrays also impacts the land. For example, machinery can compact soils, and sometimes topsoil is removed, which can degrade soil quality. In addition, solar developers may have liability concerns associated with giving too many people access to a solar farm, especially if they are using farm equipment. If solar photovoltaic panels, racking systems, conduit, or inverters are damaged, it could result in less solar energy generation and add repair expenses.

Are There Agrivoltaic Installations Already In The US?

There are numerous utility-scale solar farms that involve food production, and sheep grazing and native groundcover for pollinators have become relatively widespread. Sheep grazing is an increasingly popular way to reduce mowing costs, and numerous solar projects incorporate grazing, especially across the Midwest and Eastern United States. In addition, some projects involve honeybees, native pollinators, and crop production.

  • In Elizabethtown College in Pennsylvania, a solar farm provides 20% of the campus’ electricity. It features a pollinator-friendly ground cover and landscape buffers that create habitat for bees, birds, butterflies, and other small wildlife. The college has honeybee hives and uses the solar farm as a living laboratory.

  • At Grafton Solar in Massachusetts, a community solar farm, lettuce and squash are planted among rows of solar panels, and cattle graze part of the site. The site was developed with agrivoltaic research in mind, and UMass Amherst researchers are studying how the solar panels impact agricultural production.

  • In Midcoast Maine, low-bush blueberries are growing under solar panels. Researchers from the University of Maine Cooperative Extension are using the project as an educational model to study how to harvest, mow, and spray crops.

  • Jack’s Solar Garden with the Colorado Agrivoltaic Learning Center connects students and community members with clean energy and local food production at this 1.2-megawatt solar project.

Are There Other Types Of Dual-Purpose Land Use We Could Employ In The US?

Another dual-use approach at solar farms is creating pollinator habitat with native groundcovers and landscape buffers. In fact, pollinator habitat at solar farms could help increase agricultural productivity and crop yields on nearby farms. Using native wildflowers can reduce mowing expenses and the associated carbon emissions. Likewise, native wildflowers are usually more drought-resistant than many grasses, so they can reduce water use. Establishing a pollinator habitat is relatively easy to achieve and doesn’t require modifying the solar farm layout.

“The long-term cost over the life of the facility to maintain pollinator habitat is half or even less than the cost to establish and maintain turfgrass,” says Heidi Hartman, an Argonne National Laboratory researcher. “I’ve seen a variety of costs, and it varies job by job because of the mowing costs.”

“In the first 4 years, pollinator habitat is more expensive because the wildflower seeds are more expensive than the turfgrass seeds. Once established, native wildflowers need much less maintenance and they only need one mowing a year. They are also much more resistant to drought and soil erosion. Also, 20 years down the road, the soil underneath will be in good condition to return it to valuable cropland.”

Agrivoltaics Could Bring New Meaning To Agricultural Land In The US

A considerable amount of farmland has been lost in the last few decades in the U.S., and this trend is likely to continue. Unfortunately, one of the many causes is solar farm development, but the use of agrivoltaics and solar farms is enabling agricultural and solar power production on the same plot of land.

Sheep grazing at solar farms is growing in popularity and is becoming somewhat widespread. Although the cultivation of crops on solar farms is relatively rare, researchers are examining ways to make it more common and cost-effective. In addition, some solar developers are using native groundcovers and landscape buffers to help promote pollinator habitat.

Want to learn more about how solar technology is evolving? Learn about transparent solar panels and perovskite solar cells on the GreenLancer blog.

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