With many solar arrays ending up on farmland, a movement is fast taking hold to make sure that they will benefit the environment, agriculture and wildlife, and not just create a sea of silicon.
Allowing sheep to graze among solar panels has become one attractive antidote.
Grazing by sheep and other livestock joins other dual uses: planting groundcover to benefit pollinators, growing marketable plants such as cherry tomatoes and lavender under the panels, installing beehives and maximizing soil health practices to improve the land for later ag use. Projects that combine farming and solar energy are called agrivoltaic.
State agencies in Virginia, Maryland and New York have all created pollinator-friendly scorecards for solar developers, underscoring the expectation that environmentally beneficial groundcover will become the norm on both rural and urban solar farms.
“Solar [arrays] on farmland should be required to be dual use,” said Arjun Makhijani, founder of the Maryland-based Institute for Energy and Environmental Research.
The use of solar sites for livestock grazing is still in its infancy, but flocks of sheep are already grazing contentedly under and around glass panels in Pennsylvania, Virginia, Maryland and New York.
By welcoming the grazers, solar operators save money on land maintenance. After the cost of leasing the land, vegetation management is often their top expense.
Sheep owners get access to new grazing pastures while receiving payments to boot, adding precious income at a time when many farmers are struggling. Studies find that sheep farmers often are paid $300–$500 an acre.
There are environmental benefits as well. For example, a new study funded by the National Renewable Energy Laboratory found that native vegetation munched on by sheep shows an uptick in carbon capture and improves the soil by increasing the cycling of nutrients, carbon and water.
The synergies of grazing and leaving the ground undisturbed can actually improve a farm’s soil during its use as a solar site, according to a study by the Institute for Energy and Environmental Research, based on solar projects on three Maryland farms. Farmers want and financially need the opportunity, the study said.
Why are sheep the most popular choice, at least for now? Because most solar arrays are too close to the ground to accommodate cattle. A solar project being built in Howard County, MD, though, has panels 6 feet off the ground so cows can graze on hay planted underneath. Goats tend to eat wiring and jump onto the panels. Pigs wallow.
Sheep, on the other hand, fit nicely under the panels, typically built 2–3 feet off the ground, and they keep their heads down for the business at hand. The panels provide shelter and shade. Studies are also finding that vegetation planted for grazing under solar panels helps keep the panels cool, boosting energy production.
While I have no bone to pick with the idea of the dual use, let me point out an inescapable inefficiency. The purpose of solar panels is to intercept solar light, and convert it to electricity. The plants that sheep (or cows or goats or pigs) eat require sunshine to grow. There is, therefore potentially less growth, a lot less growth on a plot of land covered with solar panels, requiring more acreage to support the same amount of sheep than ground not covered with panels.
This just affirms the fact that there is no such thing as free electricty. Besides the not inconsiderable manufacturing costs of solar cell, and the mining and pollution required, solar (and it's renewable relative wind), require huge areas of land be set aside, and restricted to only certain dual uses.