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Growing specialty crops under solar panels shows promise

Candace Krebs
Colorado State University Specialty Crops Program Coordinator Mark Uchanski was initially skeptical when Sandbox Solar approached him about researching the possibility of combining solar farming with high-value crops. “Quite frankly, I said, this is a little bit crazy, but let’s try it,” he recalls. Three years of research now demonstrates several ways the panels and plantings benefit each other.

Colorado continues to lead the nation in pioneering the concept of solar farming done in combination with the production of high-value specialty crops.

Standing in the middle of Colorado State University’s Agricultural Research, Development and Education Center (ARDEC) South horticultural research farm east of Ft. Collins earlier this fall, CSU Specialty Crops Program Coordinator Mark Uchanski described what makes the university’s “agrivoltaic” project so revolutionary.

“The most exciting aspect is that the trial is fully replicated and that makes it scientifically sound. This is the only site I’m aware of that is evaluating food crops under multiple panel types,” Uchanski said.

He and other researchers in the program offered updates on a variety of projects during a fall field day held virtually this year at CSU’s Horticulture Field Research Center.

Solar arrays can mimic the benefits of hoop houses, Uchanski said, by moderating sun and wind and creating favorable micro-climates for growing a wide range of fruits and vegetables.

The transparency of the panels, which can range from 5 to 40 percent, makes some better suited to certain crops.

“Forty percent is the most transparent array at the plot, and we saw the best results under this one,” said Tom Hickey, a grad student in the horticultural program. “It’s not a complete shade, but it seems to offer the perfect intersection of shade and light.”

No surprise, but panels that are completely opaque, allowing little to no light to come through, appear to work best for leafy greens, kale and other cool season vegetables, while tomatoes and peppers do better under the most transparent panels.

CSU is evaluating soil moisture and temperature data obtained through a module on each panel that can be plugged into a computer for analysis. The individual panels can be tilted to allow equipment to pass through the field during planting and harvesting.

Panels moved into a flat position have another benefit for growers in Colorado: the potential to protect crops from hail.

CSU is working on developing technology that would automate the panels to tip and flatten if a hail event is anticipated.

Other benefits include better soil moisture retention and water use efficiency, diffusion of light during the hottest part of day (preventing scalding or drying out of plants and fruit) and potential to extend the growing season by offering protection from frost.

The plants benefit the panels, too, by absorbing warmth and preventing overheating.

The research is being done in collaboration with Sandbox Solar, a four-year-old start-up that provides residential installation and commercial projects, including electric vehicle charging stations. Founder Ian Skor originally proposed the research project to CSU; it is being funded by a small business innovative research grant from the U.S. Department of Agriculture’s National Institute of Food and Agriculture.

Skor had already learned from past experience that solar farms are difficult to site in highly populated areas where land values are high.

While attending college in Syracuse, New York, a progressive community favorable to renewable energy, he witnessed pushback when a community solar garden was proposed. While residents were generally in support of renewables, they didn’t like the idea of taking land out of agricultural production to do it. The two uses seemed in opposition to each other.

That instilled a passion in Skor to “change up the land use model a little bit” by pursuing a dual-purpose approach.

He drew further inspiration from an existing model that has already been highly successful in rural areas: co-locating wind farms with existing farms and ranches. “Co-locating these systems increased the adoption of renewal fuel in rural areas,” he said.

The CSU project consists of three different types of panels that together generate enough energy to power two homes. According to the National Renewable Energy Laboratory, the state would need up to 650,000 acres of renewable production to meet its climate and clean energy goals, which Skor has determined is achievable.

Several models for combining solar farms with agriculture have already become popular, most notably grazing sheep or establishing pollinator habitat under the panels, he said.

Skor is excited to see the model expand to specialty crops, including hemp. He believes a synergistic system could prove ideal for small acreage growers.

“The permaculture mindset is what brings it all together,” he said. “Land in Ft. Collins is very expensive, and finding land to develop can be a very big challenge. I’m just looking for niches where we can advance this.”