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The International Energy Agency recently said solar farms were among the cheapest sources of electricity. It called solar “the new king of electricity”. But there has always been one aspect of solar that, unlike costs, cannot really change: land need. Solar farms need a lot of land and critics have used this as an argument against the future expansion of this form of renewable power generation. Proponents, however, have found ways to not just solve this problem but do it with benefits for another industry.
Agrivoltaics refers to the dual use of farmland for solar power generation and farming. A one-megawatt solar installation requires some 4 to 5 acres of land, depending on the panels used. But you can’t just build a solar farm on any four or five acres of land anywhere. For optimal efficiency, these panels need optimal locations. It so happens that these locations usually are on arable land. And those experimenting with the combination of solar and farming are reporting pretty encouraging results.
For one thing, farmland is good for solar panels. A study from Oregon State University from last year, for example, found that when installed on farmland, solar panels had a much greater efficiency: “Solar panels are just like people and the weather, they are happier when it’s cool and breezy and dry,” said one of the authors of the study, Associate Professor Chad Higgins.
But the combination of solar and farming is also good for farming. Plants growing in the shade of solar panels need less water, meaning growing them becomes cheaper, Higgins told Oilprice.com. And while the idea of growing plants in the shade of solar panels might sound sub-optimal for the plants, Higgins notes that “Plants won’t use light beyond their light saturation point, which, for many crops is lower than the available sunlight. Crops with the lowest light saturation points are already grown in shaded conditions (coffee, some small fruits, medicinal herbs, leafy greens etc.).”
And this is not all. The shade of the solar panels actually protects the plants growing underneath them during the hottest hours of the day, says Marcus Krembs, Head of Sustainability at Enel North America. He adds that early research into agrivoltaics suggests solar panels in warmer areas can even increase the yield of some crops.
As regards some regular activities in farming, such as harvesting, for example, or plowing, these are also possible with solar panels simply mounted higher, explains Dan Orzech, general manager at the Oregon Clean Power Cooperative. Higher panels, however, would be costlier, notes Orzech, but there is another alternative: spread the panels thinner so you can use farm equipment where it is needed.
Solar panels can also have beneficial effects on animal farms. Because they increase water retention in the soil, they can stimulate more abundant vegetation for sheep and other farm animals to graze. This has the win-win nature of keeping the sheep fed while eliminating the need for mechanical trimming of the grass, explains the Oregon Clean Power Cooperative’s Orzech.
According to Enel Green Power’s Krembs, solar farms can also stimulate the population growth of bees and other pollinators.
“Creating shared value through farmable solar sites not only preserves the land but also takes proactive site preparation measures, including planting beneficial vegetation, often friendly to bees and other pollinator insects, while providing habitat for native species that require less intense maintenance and mowing,” he said, citing the results of Enel Green Power’s partnership with the National Renewable Energy Laboratory.
“Sheep thrive on solar farms, and it is a natural combination,” says Dr. Gavin Harper at the University of Birmingham, author of “Solar Energy Projects for the Evil Genius” and “Domestic Solar Energy”. “They munch on the grass and vegetation around the farms, keeping it low and preventing overshadowing. Meanwhile, the panels provide shade and cover for the sheep in hot and inclement weather.”
At first glance, solar power and farming seem mutually exclusive. Once you take a closer look, however, they appear to be mutually beneficial in more than one way. As Enel Green Power’s Krembs notes, even solar farms on non-farm land have beneficial effects on that land. When built on farmland, the benefits of the combination only seem to become greater.
This is largely thanks to the flexibility of solar panel technology. As OSU’s Higgins explains, to make space for tractors and harvesters in fields, you can make the panels higher or tilt them, so they stay out of the equipment’s way. Interestingly, agrivoltaics may drive innovation in machinery as well.
“Long term, I think there will be a co-evolution of next-generation farm equipment and PV racking solutions,” Higgins told Oilprice. “Already, companies like Rippa and John Deere (among others) have driverless, electric tractor prototypes. These low-profile systems have tremendous promise for use in agrivoltaic systems.”
This co-evolution could also extend to plants. Since agricultural land is the best for solar farms, we may in the future see more and more agrivoltaics projects. This would drive efforts to optimize the plant component of the combination so benefits are maximized and any disadvantages minimized.
