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By Kathiann M. Kowalski

Energy News Network

Research underway at a Madison County, Ohio solar farm promises to shed light on how well multi-use farming can work at a large scale. The answers will help shape best practices for future projects, while addressing some concerns raised in ongoing debates over siting large solar projects in rural farm areas.

Spread across more than 1,900 acres, the 180 MW Madison Fields project will be one of North America’s largest test grounds for research into agrivoltaics — essentially farming between the rows on photovoltaic solar projects.

As farmers seek to lease land for solar arrays to diversify their incomes, the practice could help them maximize their income and fend off opposition from critics concerned that solar development will take prime farmland out of production.

Some farmers have also said the revenue from clean energy can help keep their farms operating amid pressure from housing developers. A recent report from the American Farmland Trust says Ohio could lose more than 518,000 acres of farmland to urban sprawl by 2040.

That number dwarfs the roughly 95,000 acres for certified and other projects noted on the Ohio Power Siting Board’s most recent solar case status map. 

Yet solar projects generally deal with big chunks of land at once, while urban sprawl happens bit by bit over time, said Dale Arnold, director of energy policy for the Ohio Farm Bureau. Helping people understand and appreciate that is “absolutely huge,” he said.

Savion, a Shell subsidiary, developed the Madison County project, and it began commercial operation on July 11 with Amazon as the long-term buyer for its energy. Yet work began much earlier this year to set up the site for research by Ohio State University scientists, Savion’s Between the Rows subsidiary, and others.

“People have a lot of questions with regard to energy development going forward in this state,” particularly when it comes to taking land out of use for agricultural production, Arnold said.

Yet today’s industry continues to shift away from coal to a diversified portfolio of natural gas, nuclear, hydropower, wind energy, solar energy and other types of generation. Forecasts also show there will be growing demand for electricity by mid-century, he said.

“Finding a balance where you can do a number of things on the same ground — in this case energy production as well as agricultural production — is obviously huge,” Arnold said. If agrivoltaics is to become more than a buzzword, though, both farmers and solar project developers need to work out best practices.

One big issue is what crops can work well for large-scale utility projects. Compared to most solar farm projects in Eastern and Piedmont states, utility-scale solar projects in Ohio and other Midwestern states can spread across 1,000 acres or more, Arnold said.

“You hear a lot about produce and specialty crops,” for example, said Sarah Moser, Savion’s director of farm operations and agrivoltaics. But raising them is “hard to do on 1,000 acres.”

Hay, you!

Moser and Ohio State University researchers think forage crops like alfalfa and hay hold promise. Operations can be scaled up for large areas, said Eric Romich, an Ohio State University Extension field specialist for energy development. And the crops wouldn’t grow too tall amid the panels.

“We also wanted something that we felt had the potential to be economical,” Romich said.

Two 2023 reports by Ohio State University Extension researchers found raising hay and alfalfa between rows of solar panels was feasible and that the harvest’s nutritive value was good. But that small-scale work at the Pigtail Farms site in Van Wert County used data from only a few test plots and controls, which is an important limitation, Romich said.

Work at Madison Fields will now test whether similar results can be achieved at large scale. Part of a $1.6 million grant from the Department of Energy will help pay for that work over the course of four years.

Other research will test how well plants do in sun versus shade, Romich said. That matters because some portion of the land among solar panels will always be shaded.

Researchers planted the crops on test fields and control areas this spring, with an eye toward starting to collect data next year. “Forages are quite temperamental in terms of trying to get them established,” said Braden Campbell, an animal scientist at Ohio State University who is also working on the project. The team has found compacted soil around the solar panels, “but we are relieved to see that the seeds that we put into the ground are growing,” he said.

Moser plans to work with other crops, too. Soybeans are one example. They were already used as a cover crop before alfalfa and hay were planted. Soybeans can also work into a crop rotation when forage crops need to be replanted every few years.

“The market is there for it, and it does well” as a hardy crop which can also loosen soil and restore nutrients to it, Moser said, adding that local communities have expressed interest in the crop as well.

Send in the sheep

Other work at Madison Fields will explore complementary grazing. The goal is to harvest the forage crops as efficiently as possible. But there will still be a need for vegetation control under and around panels and other infrastructure, said Campbell. So, after harvesting, sheep will go to work.

“To me, that’s three commodities that we can get off one unit of land,” Campbell said: Solar panels will produce electricity. Hay and alfalfa growing will provide a crop. And the land will help support sheep, which in turn can produce meat, milk and fiber.

Other solar farms already use or plan to use sheep for vegetation control. But “there is a big difference” between using sheep to keep plants under control and relying on that for their nutrition, Campbell said.

Studies will need to test the health of sheep that do complementary grazing, compared to other sheep. Other questions include finding optimal grazing rates of sheep per acre, as well as other logistics. But first, the forage needs to establish good roots so it can withstand the pressure of grazing.

Tractors and more

A third bucket of research questions under the Department of Energy grant will focus on farm equipment. Tractors and other farm vehicles need to fit between the rows with their attachments. There’s been a trend in the agricultural sector toward wider equipment, which can cover more ground quickly but may not fit between rows of solar panels, Moser said.

“But a lot of farmers still have smaller equipment,” Moser continued, because some parcels aren’t appropriate for wider machinery. Maneuvering 15-foot-wide equipment works fairly well, and 17-foot and even 20-foot widths can still work. 

“I could get my 20-foot drill in there,” Moser said. “I just have to be careful.”

Arnold speculated that some companies may develop special equipment whose attachments can fit under solar panel rows more easily. Other possibilities could include raising panels or even feathering them when agricultural equipment is in use, he suggested.

Farm equipment doesn’t just need to go down an alley between two rows of solar panels. It will also have to turn around at the end to go down another one, Arnold said. So, there needs to be an adequate turning radius, without cables blocking farm vehicles’ paths. Poles, stands, and other equipment also can’t block the path of the farm equipment, he said.

The research can help guide the design of future solar projects to be “hay-ready” sites, Romich suggested. At the same time, agricultural operations shouldn’t jeopardize the safe and efficient operation of a solar facility. “It’s an operating power plant,” Romich said.

Arnold has additional questions about infrastructure needs: What facilities will be necessary to dry, bale and store forage? What facilities will other crops need? And how will they be trucked out to markets?

Likewise, what equipment and facilities will be needed for any sheep kept on site?  That includes paddock fencing, water, and so forth. And where will their caretaker live? 

“You’re going to have to have people there full-time,” Arnold said.

Precision agriculture

The Ohio State researchers, Moser, and others also wonder how well precision agriculture can work with solar farms. The term refers to methods that rely on technology and data to guide farmers’ work. The range of technologies includes remote sensing of field conditions with drones, in-ground sensors, automated weeders and more.

The big question is which precision agriculture technologies can work well for crops planted between rows of solar panels as they generate electricity.

It’s unclear what any of the studies will show until data has been collected and analyzed, Romich said. By the end, he feels the work will provide a better understanding of what will or won’t work.

Economics questions about business models, contractual arrangements and more also must eventually be worked out, Arnold said. At the end of the day, farmers will need to make a profit if agriculture is to successfully blend with solar projects.

“The possibilities are limitless, really,” when it comes to business arrangements, Moser said. “My motto is always, ‘farmers figure it out.’ And if we work with them, we’ll figure…out how to do this with best practices.”