Stabilizing the climate requires a rapid transition to 100 percent carbon-free power, which will require large increases in solar power generation. In the U.S., the Biden administration has outlined a plan to power 40 percent of the U.S. power grid with solar energy by 2035.
Compared with agriculture and ranching, the land requirements of solar are quite small. Research from the National Renewable Energy Laboratory finds that just 0.6% of the country’s land mass would be needed to power the entire country with solar power. Still, utility-scale solar projects can require hundreds of acres, and new solar projects sometimes face resistance given competing needs for food-producing farmland or recreational space.
But new studies point to the multiple benefits of combining solar electricity generation with agricultural production. From water conservation to food production, habitat restoration, and local economic development, the research demonstrates that the “multi-solving” power of agrivoltaics (combining solar in concert with other agricultural land uses) can increase public support for solar development, offering an opportunity to avoid or resolve conflicts.
Saving water and energy while improving animal welfare
Finding sufficient water for food production in the western United States has always been challenging given the arid climate, but climate change-fueled droughts are making the situation worse. To get at this growing concern, University of Arizona researchers tested their own agrivoltaic system: They planted chiltepin pepper, jalapeño, and cherry tomatoes under a solar array and compared the results to a traditional, open-sky planting area for three months.
The researchers found the panels helped moderate ground temperatures, reducing water use and improving carbon uptake among the plants. Remarkably, food production doubled under the agrivoltaic system. And because water evaporation from the plants cooled the panels, the solar system itself generated 3% more electricity during the summer, showing how both food and solar production can perform better when done in collaboration.
Agrivoltaics can support plant production, but with what effects on animals? Pasture for animal grazing uses about one-fifth of all land in the U.S., much of it in the West, where natural solar resources are also the greatest, presenting a major opportunity for agrivoltaics. Researchers at the University of Oregon investigated the effects of installing solar arrays on active grazing land, comparing a traditional open pasture farm with the Rabbit Hills Solar Farm in Oregon, which combines sheep grazing and solar energy generation.
Sheep in the agrivoltaic system consumed the same or less water, as they spent a lot of time in the shade of the solar panels during the hottest months. While the pastures in the agrivoltaic system produced less grass, the nutrient quality and seed content was higher: As a result, lamb production was similar in both systems, but land productivity was much greater in the agrivoltaic farm.
In another study, in Texas, researchers found major environmental benefits when they evaluated the emissions and energy-use impacts of combining solar generation with pasture-fed rabbit farming. Compared with non-integrated conventional rabbit farming, the agrivoltaic rabbit farm used its own locally produced solar for energy, demanding 98.8% less fossil energy from the grid. In addition, the pasture-raised rabbits in the agrivoltaic system required no external feed, and the pasture did not need mowing, resulting in 98.5% fewer greenhouse gas emissions compared with conventional rabbit farming alone.
Overall, these two studies suggest that combining pastureland with solar generation would have no negative impact on animal productivity but would provide an opportunity to improve water conservation and animal welfare and offer steep cuts in emissions from farming operations and significant increases in land productivity.
Restoring pollinator habitat
Another study explores the roles of pollinating insects as a cornerstone of natural and agricultural ecosystems. These insects contribute to the reproduction of 75 percent of flowering plant species and 35 percent of crop species globally. But the number of pollinators has declined dramatically in recent years as a result of habitat loss and pesticide use, further aggravated by accelerating climate change – presenting a major threat to food security. Given that land underneath solar installations is often unused, filling the area below with habitat for pollinating insects could help protect these critical species, and researchers are examining this potential.
Researchers in a study of the Eagle Point Solar Plant in southwestern Oregon found that land used for solar arrays does indeed make excellent pollinator habitat and that pollinators were just as likely to visit flowers under shaded areas as they were in unshaded areas. In addition, the researchers found that the cooler, moister microclimate in the partially shaded areas under solar panels both increased floral growth and delayed flower blooming time. The delayed blooming is key for sustaining pollinator populations, as it can help support pollinators in the late summer when food is scarce but still needed for migration or winter storage.
Increasing public support
Although Americans overwhelmingly back renewable power, that support doesn’t always play out when a project is planned for one’s backyard, and local opposition can delay or even block proposed solar or wind installations. Still, the research shows people value the multi-benefits that agrivoltaics bring to their local communities. A survey of approximately 2,000 respondents in Michigan and Texas, for instance, found 81% were more likely to support solar development in their community if it combined energy and agriculture production.
Survey respondents said they preferred projects that provide economic opportunities for farmers and the local community, do not threaten local interests, and ensure fair distribution of economic benefits. These results suggest that solar projects that integrate other land uses in ways that directly address the local community’s needs are more likely to head off possible local opposition.
Tackling multiple problems with a single solution
Without a rapid buildout of new solar power generation, greenhouse gases won’t be cut in time to avoid the most dangerous consequences of climate change. But climate change is a threat-multiplier, worsening drought, food scarcity, and extinctions. An emerging body of research is demonstrating that agrivoltaics can help support the expansion of solar power while tackling other serious challenges and delivering additional benefits to surrounding communities. Agrivoltaics can also help shore-up public support, especially in rural areas, helping to accelerate the clean energy transition. With so much under threat from a fast-accelerating warming, these kinds of multi-solving projects will be key for both cutting emissions and for bolstering resilience.
Martín Bonzi is Program Associate with the Aspen Global Change Institute, and Sarah Spengeman, Ph.D. is Deputy Director of Communications with Energy Innovation LLC.
Editor’s Note: Yale Climate Connections is partnering with Aspen Global Change Institute and Energy Innovation to publish monthly reviews of new and recent climate-related scientific research. AGCI has also published a more in-depth review of this research, which you can access here for more information.