As the drive for renewable power ramps up, more and more land is being covered with solar panels. However, this is not necessarily taking away land from agriculture. Instead, an increasing number of ranchers and farmers are developing symbiotic relationships with energy providers. The land under and around solar panels can be used to grow food.
Crops and livestock can benefit from growing or grazing around solar panels. An array of panels creates its own microclimate. The structures produce shade and reduce wind flow, and at night, the panels radiate heat. The result: greater retention of moisture, partial shade during the day, warmer nights and calmer air. Researchers have looked at various models of agri-voltaics including the following.
Grassland: On a droughty pasture, Hassanpour, Selker and Higgins (2018) found that the soil under panels held moisture better than similar ground without panels. The soil under the solar array was 328% more efficient in terms of water use (plant biomass produced per unit of water used). Late season plant growth was 90% greater under the panels.
Vegetables: Vegetables can thrive under panels due to warmer nights, less wind and greater soil moisture. The key is choosing crops that grow well under shade. In Arizona, hot peppers and cherry tomatoes benefited from the cooler temperatures (Barron-Gafford, et al, 2019). In much of Canada, salad greens and brassicas might be a better choice.
Grazing animals: Perhaps the best mix of agriculture and photovoltaics is allowing sheep to graze under solar panels. The sheep perform the necessary job of controlling vegetation, which would otherwise shade the panels. Sheep even do a more thorough job than lawnmowers as they can reach around the legs of the structures. In return, they receive forage and a shady place to rest. Goats can be as effective in the job of grazing but, not surprisingly, they also have been known to damage equipment by climbing on and chewing structures. Beef can work well if the panels are raised higher from the ground.
The arrangements between the power company and farmer vary. Sometimes farmers use land that is already owned or rented by the utility. Other times, the utility may pay rent to the farmers to erect structures on existing farmland.
For a Canadian example of sheep grazing under panels, see the CBC link cited below. Also, see Fletcher and Lewis (2014): a report based on the experience of four Ontario farmers who visited several examples of photovoltaic grazing in the U.K. and described how they might adapt the lessons they learned to the Ontario farming context.
Sources & resources:
— Barron-Gafford, Greg, Mitchell Pavao-Zuckerman, Rebecca Minor et al. 2019. Agrivoltaics provide mutual benefits across the food–energy–water nexus in drylands. Nature Sustainability. 2. 10.1038/s41893-019-0364-5.
— Hassanpour, Adeh Elnaz, John S. Selker, Chad W. Higgins. 2018. Remarkable agrivoltaic influence on soil moisture, micrometeorology and water-use efficiency. PLoS One. Nov. 1; 13(11):e0203256.
— Fletcher, Kent and Donald Lewis. 2014. Large Scale Photovoltaic Facilities ‘Solar Farms’: Solar Power And Agriculture. The English Experience. solargrazing.org/canadian-guide-to-solar-grazing
— Rural Solar Stories: ruralsolarstories.org
— American Solar Grazing Association: solargrazing.org
— Cotnam, Hallie. 2019. Sheep farmers, solar company form powerful partnership. CBC News Ottawa. July 1.
— www.cbc.ca/news/canada/ottawa/solar-energy-panels-weeds-sheep-lambs-farming-grazing-1.5190376.
— Janet Wallace