If Your Sweater Feels Better Thank An Agrivoltaic Project

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Solar developers are beginning to tap the emerging field of agrivoltaics to help build community support for new solar projects in rural areas. They have a powerful case to make. In an agrivoltaic project, solar panels complement farm activities. They help small farmers earn new revenue and provide new opportunities for other local businesses, while promoting biodiversity and soil health — on top of generating zero emission electricity, of course. In a new twist, researchers have also uncovered evidence that grazing among solar panels can help improve the quality of sheep’s wool.

Agrivoltaic Projects And Livestock Farms

The science of agrivoltaics emerged just a few years ago, when researchers began compiling evidence that rural solar arrays can support agriculture. Shade from the array protects soil and vegetation from excess heat and sun, helping to reduce evaporation and conserve water. Meanwhile, plants that grow under and around the solar panels contribute to a cooling environment that helps improve solar conversion efficiency (see more farming + solar background here).

Initially, agrivoltaic projects focused on shade-tolerant pollinator habitats, native species restoration and livestock grazing within conventional ground mounted solar arrays. More recently, the knowledge base has expanded to deploy raised racking and other specialized systems that tailor solar arrays for orchards, vineyards, row crops, and field crops.

Still, solar grazing remains among the more accessible deployments of agrivoltaic arrays. The solar panels provide livestock with protection from heat and weather. Meanwhile, grazing prevents vegetation from overgrowing the solar panels, reducing if not eliminating the expense and carbon emissions related to machine mowing.

Better Wool, With Agrivoltaics

Compared to other livestock, sheep have earned a good reputation as solar grazers. Unlike goats, sheep do not chew through wires or clamber onto solar panels. Sheep are also much smaller than cattle and horses, helping to avoid the chance of damage to the racking systems and other equipment.

The solar developer Lightsource bp (a branch of bp) is an early adopter of agrivoltaics, and they have been taking a closer look at the effect of solar arrays on the quality of sheep’s wool. So far, they like what they see.

Last month, Lightsource reported the results of a second round of wool testing from sheep grazing at its Wellington solar farm, located in New South Wales, Australia. The tests demonstrated that solar-grazing merino sheep produce wool that meets high quality standards. That provides important, science based evidence against critics who claim that proximity to solar panels is harmful to grazing animals, among other complaints.

The second round of testing also provided evidence that the quality of the wool of solar-grazed sheep improved in some aspects. Lightsource cautions that longer-term studies are needed before that observation is confirmed conclusively. If the improvements are confirmed, then solar developers, farmers and other stakeholders will have an even more persuasive argument in favor of solar grazing.

Healthier Sheep, With Agrivoltaics

In a related development, last year a team of researchers from Wageningen University in the Netherlands and California Polytechnic State University in the US set out to determine the most efficient ways to manage grazing in agrivoltaic projects, using the Gold Tree Solar Farm on the Cal Poly campus in San Luis Obispo, California as a research site.

Like any other grazing paddock, an agrivoltaic project is an enclosed space that requires careful livestock management to ensure adequate nutrition is available, without overgrazing or damaging the soil. The management chore is also complicated by seasonal conditions, weather extremes, and the age of the livestock among other variables. Typically, the livestock is rotated from one area of the paddock to another, at varying rates of frequency.

When the researchers assessed sheep grazing at Gold Tree, something interesting came up. Regardless of the rotation schedule, sheep in the agrivoltaic array spent more time grazing than a comparison group that grazed in paddocks without solar panels.

“The presence of solar panels may have provided sheep relief from heat, wind, and rain, which could increase grazing activity,” the researchers surmised. In addition, the researchers determined that forage in the solar array was more digestible and had a higher protein content than forage in the paddocks.

On a cautionary note, more time spent grazing can indicate good health, but that depends on a variety of factors. Still, the finding of more nutritious forage in solar arrays could help explain improvements in wool quality found by the Australian research project.

Best Practices For Solar Grazing

At just 4.5 megawatts, the Gold Tree Solar Farm is tiny by today’s standards. However, as a research facility it can have an outsized impact on the pace of agrivoltaic activity in the US. In addition to providing room for grazing, Gold Tree also demonstrates that grazing leaves plenty of room for solar energy.

Gold Tree began operating in 2018 as the biggest solar array in California’s public university system, providing about 25% of electricity demand at Cal Poly while saving an estimated $17 million over its 20 year lifespan and serving as a hands-on photovoltaic laboratory. The developer, REC Solar, was selected partly on account of a data monitoring dashboard that provides detailed information for researchers and staff.

More to the point, last year’s grazing study at Gold Tree was not a one-off. It is part of ongoing research at the Cal Poly Animal Science department, aimed at building a knowledge base for vegetation management within rural solar arrays.

Engaging Community Support For Rural Solar Development

The leading global solar developer EDF Renewables, for one, is not waiting around for the research to ripen. Last month, the company announced that its intention to deploy agrivoltaics in its very first project in the US, the proposed Eastern Cottontail Solar Project in Fairfield County, Ohio. The plan is to host sheep along with 220 megawatts’ worth of solar panels.

If the plan is approved, it would provide a high profile model for other solar developers to follow, helping to push back against opposition campaigns influenced by fossil energy stakeholders.

With agrivoltaics in hand, EDF can push the community benefit angle over and above the expectation of tax revenue. “This initiative will create market opportunities for local shepherds, generate additional jobs, and drive further economic throughput by unlocking opportunities to advance regional agricultural-based industries such as meat, dairy, and wool,” EDF explained in a press statement last month.

Other solar developers that hope to follow EDF’s path will have to put in the work. EDF began getting feedback from the community four years ago, leading up to presentation of the agrivoltaic proposal in October.

“Over the last four years, a hallmark of our project has been substantial engagement with the local community as a means to listen to concerns and incorporate feedback, which has created trust and established a strong partnership,” explains Nick Lucania, who heads the Cottontail project for EDF.

“The most common concern we’ve heard is that while solar utilizes privately-owned land, it can displace active farmland. In response, we proposed incorporating sheep grazing to the community, allowing a solution to help land be productive for both energy generation and agriculture,” he noted.

Keep an eye on Cottontail as the project works its way through the approval project. In recent years, Ohio has earned a reputation for turning down solar developers, partly by giving outsized consideration to the aesthetic concerns of local residents. Developers argue that Ohio law requires planning boards to give equal consideration to a list of community economic benefits and statewide energy priorities, among other factors. If the agrivoltaic proposal works as planned, Cottontail will succeed where others have failed.

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Photo: Solar researchers have uncovered some tantalizing clues about the impact of agrivoltaic projects on the health and grazing habits of sheep, leading to a connection with improvements in wool quality (courtesy of Lightsource bp).