Casting shade is solar’s new superpower

In rural America, shoulder-high corn is increasingly competing with a new cash crop: solar energy. Acres of solar panels shine brightly on fields along interstates and rural byways, signaling a change in how America’s farmland generates income. The need for a happy marriage between these old and new industries has inspired a burst of innovation and a new word to describe the combination: Agrivoltaics.

The Inflation Reduction Act includes billions of dollars in renewable energy funds that will accelerate the adoption of solar and other renewable energy sources. Some of the new solar panels will land on rooftops, but most will be concentrated in large utility scales that the U.S. Department of Energy says could eventually cover an area roughly equivalent to Massachusetts, Rhode Island and Connecticut.

Solar panels work best in light winds, moderate temperatures and low humidity. Roofs share some of these characteristics. But nothing maximizes this combination of properties like cropland. For solar developers eager to get the most out of their investment, that makes farmland irresistible.

For farmers, the attraction is mutual. Depending on the location, solar energy can be one of the most profitable uses of land. Texas farmers can receive as much as $500 an acre annually from solar leases, and California’s Central Valley farmers occasionally see as much as $1,000 per acre. It’s easy money compared to the complicated and often uncertain business of agriculture.

But the potential scale of these new projects has rattled some farming communities, where opposition is growing and threatening efforts to decarbonize the U.S. electricity supply.

Critics focus on the downsides of converting farmland to solar energy. Panels are typically placed 18 to 36 inches off the ground, blocking access to the ground. Some don’t like the aesthetics and fear that huge solar panels will change the rural character of their community. Meanwhile, false, social media-driven conspiracies about the installations’ alleged negative health effects are growing in influence.

Right or wrong, growing opposition to solar power in rural America is putting climate progress at risk, James McCall, a researcher at the Energy Department’s National Renewable Energy Laboratory, said in a call from Denver. “We have to find a solution that is a middle ground,” he said.

Brad Heins, a professor of animal science at the University of Minnesota, is working on just such a compromise. He is a leading researcher in agrovoltaics, a growing set of technologies and methods designed to exploit synergies between energy production and agriculture. “We harvest the sun twice,” Heins explains as he unlocks a gate to a large cattle pasture in west-central Minnesota, near the border of North and South Dakota.

The sun’s energy feeds pasture fodder and crops side by side with solar panels. “For farmers, it’s a two-income stream,” Heins said. This may mean planting crops that thrive in the shade from the panels. Or, in Hein’s case, it could mean cooling cows in the shade of the panels rather than resorting to expensive fans in a barn.

Heins and his colleagues are at the forefront of this new field, but they are not alone. There are hundreds of agrovoltaic projects underway in the United States. Some work better than others and some may end up not working at all. But the best will lead to a greener and more profitable rural America that embraces renewable energy as an asset.

The idea that shading from solar panels can increase agricultural productivity dates back to the early 1980s. Japan, a country long obsessed with its limited land and energy reserves, was among the first to explore the concept. Its first known agrovoltaic plant was established in 2004, and in 2019 there were 1,992 agrovoltaic farms in the country.

For example, the high-quality green tea plant that is ground into matcha is traditionally grown under shade netting for several weeks. Laying out these nets is not only a labor-intensive process, but it can damage delicate and valuable plant shoots. Agrivoltaics offers an alternative. Farmers carefully place solar panels to provide shade, thereby eliminating the need for grids and the expensive labor to install them. Farmers who invest in the system save money on production costs while making money from renewable energy and a premium crop that they can market as sustainable.

None of these Japanese systems are designed to cover Midwestern cornfields or Texas livestock farms spanning thousands of acres. Most Japanese farms are less than 3 acres and support the cultivation of high-value, hand-harvested crops that benefit from premium markets in Japan. Their agrovoltaic projects are adapted to that model.

However, starting small is a chance to prove the concept. In the US, some of the most successful agrivoltaic pilots are also focusing on hand-harvested crops. In Arizona, researchers recently found that tomato production doubled under solar panels and was 65% more efficient in its use of water. They also found that jalapeños were 167% more water efficient, even though production remained the same. It’s an important, money-saving finding for arid agriculture, especially as the climate warms.

The benefits of agrovoltaics did not accrue only to farmers. The Arizona studies showed that solar panels with a garden growing under them stayed cooler and produced more energy. That kind of synergy is causing solar developers to look more carefully at partnering with farmers and encourage further investment in rural solar.

The question now: Can techniques that have shown their greatest promise in small-scale demonstration projects and hand-harvested farms be scaled up enough to work for crops like corn, livestock, and the communities that thrive on them?

“Twelve years ago, when I started here, I never imagined I would be doing renewable energy,” Heins tells me, standing under a solar panel at the West Central Research and Outreach Center in Morris, Minnesota. He grew up on a dairy farm, and after receiving his PhD from the University of Minnesota, his research focused primarily on organic dairy production. “But the thing is, agriculture is very energy intensive,” he said. In 2013, the research center began looking at ways to reduce its energy footprint. So, in addition to seeking efficiency gains, it also began installing renewable energy systems, including solar panels.

Agrivoltaics was part of the mix from the beginning. The center has some traditional installations only a few centimeters from the ground. But it has also cost extra to lift panels several meters into the air. As we stand under an array shared with the University of Minnesota-Morris, Heins points to the cows grazing on the other side of the pasture. “Cows don’t do well in 80, 90-degree heat,” he said. Among other problems, heat stress in cows raises body temperature and lowers milk production. A common solution is to place the cows in a barn with fans. But it requires power.

Heins and his colleagues tried a different approach: they raised the panels at least six feet, high enough to accommodate cows in search of shade. The cows didn’t hesitate to use it, and during a study, the cows stayed cooler and breathed more slowly. In other words: they were less stressed. “It’s a big problem with dairy cows,” explains Heins. Stressed dairy cows are less productive and ultimately less profitable. Heins tells me he has received calls from ranchers outside of Minnesota wanting to know if their solar systems can be made compatible with their herds.

It’s not just about the cows in Morris. During a morning tour, Heins and Esther Jordan, co-director of the research center’s horticulture department, showed me a variety of plants and crops they are trying to grow under solar panels in this pasture and others. There are good reasons to be hopeful about this work. A recent Yale study of Minnesota agrivoltaics projects found that incorporating pollinator-friendly plants not only improved the efficiency of the solar panels above them, but potentially spread benefits to surrounding farms that depend on pollinators. It’s those kinds of outcomes, along with the direct economic benefits via improved crops, that could help overcome opposition to solar panels in American farmland.

For now, the conversation is in an early phase. Agrivoltaics, at least on a large scale, remains an object of research more than a way of doing business. Furthermore, the effort of raising solar panels six to eight feet off the ground—rather than 18 inches—presents a significant cost burden, especially when the cost of steel is so high. Even more difficult, even eight feet is not high enough for many modern farm machines to work under. The large farming operations that define so much of American agriculture—and that rely on large planting and harvesting equipment—will not be a candidate for these new techniques for now.

But these are short-term problems. McCall, of the Department of Energy’s Renewable Energy Laboratory, tells me interest in agrovoltaics is high and growing. He said he’s hearing from landowners, state and local regulators, universities — “people who want to see these sites. There’s a lot of interest in setting up demonstration facilities in communities.”

That’s good news for rural communities looking for ways to diversify their economies, for farmers eager to add another income stream, and for anyone determined to see the U.S. decarbonize its power grids. Agrivoltaics will not solve all economic problems in farm country, nor will it ensure that President Joe Biden’s solar energy goals are met. But it’s an important tool that farmers and solar developers are just beginning to understand and use.

In the coming years, agrovoltaics will tie them together in an effort to build more sustainable agriculture and energy systems. That’s the reason for long-term optimism down on the farm and across rural America. More from other writers at Bloomberg Opinion:

US Green Energy is surprisingly Republican: Denning and Davies

Saving the planet is more important than saving birds: Tyler Cowen

We must learn to love genetically modified crops: Amanda Little

This column does not necessarily reflect the opinion of the editors or Bloomberg LP and its owners.

Adam Minter is a Bloomberg Opinion columnist covering Asia, technology and the environment. He is most recently the author of “Secondhand: Travels in the New Global Garage Sale.”

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