A Maine farmer pairs solar panels with wild blueberries. Will the effort pay off?

This article is republished in partnership with the Energy Information Network.

Blueberry fields and other plots in rural Maine are increasingly sought after for housing development, and farmer Paul Sweetland believes the wild blueberry sector is under pressure, especially when market prices drop.

But he hopes a new “crop” growing in tandem with berries could help boost local industry and preserve farmland. It would be solar panels installed on 11 acres of land where Sweetland grows blueberries in Rockport.

The University of Maine study this example of dual-use agrivoltaic. The solar installation was developed by the Boston-based solar developer blue waveand belongs to the company Navisun, which pays the rents to the landowner. Sweetland tends, harvests and sells the blueberries and shares the profits with the landowner.

Across the country, farmers regularly rent their land for large-scale or community solar installations, but usually the crops are not grown on that same land. With dual-use agrivoltaics, crops are grown under or between rows of solar panels, with the aim of generating renewable energy without taking farmland out of production.

Farmers or landowners can collect incentives for solar power, and some states, including Virginia, New York, New Jersey, and Massachusetts, have or are considering incentives specifically for agrivoltaics. Agrivoltaic works best with crops that don’t grow too tall, are hand-picked, and benefit from the shade the panels provide.

From mutton to blueberries

Jesse Robertson-Dubois, director of sustainable solar development at BlueWave, grew up on a farm with a vegetable garden and livestock, and launched a career as a commercial farmer and conservationist.

But soon, “the intersection of land use and solar power piqued my interest,” he said. “By further examining the ongoing national dialogue and community conversations, I have come to understand that solar energy can coexist in symbiosis with agricultural land.”

He first worked with sheep grazing under solar panels, a practice that frees up more territory for grazing while alleviating the need to mow grass around a solar panel.

While sheep are small enough to easily graze under conventional solar panels, grazing livestock or growing many crops requires taller panels. And top panels may not be financially viable without specific incentives, Robertson-Dubois noted. The Maine blueberry project was unable to exploit any particular incentives, but since blueberries are low-growing perennial shrubs, a fairly typical 4.2 megawatt array was feasible.

“We were able to do that just by sharpening our pencils and adapting them,” Robertson-Dubois said. “We really wanted to protect this culture. We realized that due to the way they are harvested, we didn’t need a lot of clearance for equipment, but we really needed to protect the soils and protect the plants during the construction phase.

Mixed results so far

The construction of the Rockport panels was carried out in three different sectors as part of the study by the University of Maine. One was of standard construction; another was labeled “mindful”, with fewer trips made by machines remaining on certain paths; and the most protective “careful” sector had mats placed over the plants and the least amount of car travel.

“Our goal is to understand the impact of construction – how will blueberries react if crushed?” said Lily Calderwood, an assistant professor of horticulture at the University of Maine and an expert on wild blueberries. “Anecdotally, the careful processing definitely recovered faster in terms of blueberry coverage. But they all recovered well.

Although the plants survived the trauma of building the array, Calderwood said it appears the blueberry plants shaded by the panels won’t produce much fruit. They won’t know for sure for several years, because wild blueberries grow in a long cycle.

The university received Northeast FARE funding in addition to USDA funding to continue the study for three years. They will compare blueberry yield between plants fully shaded by panels, plants partially shaded by panels, and plants in full sun. The panels are 8 feet tall in rows spaced 8 feet apart, Calderwood said, which she considers relatively “tight” spacing.

“We already know that plants have adapted to this new environment. We call it genetic plasticity or phenotypic plasticity – the plant can adapt to shade,” she said. “In the shade they have larger leaves which are darker green. We see that happening here. But that doesn’t necessarily mean there’s more fruit. We haven’t seen that It tends not to really produce much fruit under the panels.

An agrivoltaic project in Massachusetts with cranberries performed better, she said, perhaps because the panels are higher off the ground and more widely spaced. But more steel to elevate the panels and fewer panels in a given area makes a solar panel less profitable.

“This grid was installed with a certain purpose of power generation,” Calderwood said. So if one “increases the cost of the grid and there is less energy you get out of it, that makes it less attractive”.

She noted that soil moisture has increased under the panels in Maine, which is desirable because the soil drains quickly and seasonal droughts can be hard on the berries.

“Soil moisture is definitely a plus, but that alone can’t make up for it being so shady,” she said. She thinks it probably makes more sense for blueberry growers to convert their less productive land entirely to solar power and forego solar power on land where blueberries naturally thrive the most.

“When farmers consider this, they really want to ask themselves if they want land to be energy first or agriculture first – one or the other,” she said. “The overlap isn’t quite there yet.”

Variation by location

The National Renewable Energy Laboratory is studying agrivoltaics with crops such as kale and Swiss chard in Massachusetts, 17 types of potatoes in Oregon’s Willamette Valley, and beans and peppers in Arizona. NREL’s best-known agrivoltaic project, Jack’s Solar Garden in Colorado, generates electricity for more than 300 homes and trains young farmers to grow vegetables under solar panels. NREL is partnering with the U.S. Department of Energy to study dual-use agrovoltaics and related projects such as beekeeping and collocated pollinator habitat with solar power, through the InSPIRE project.

In Arizona, “partial panel shade has been incredibly beneficial, especially for tomatoes and peppers,” said NREL analyst Jordan Macknick. “We’ve seen tomato yields double by using 30% less water, and beans and peppers yield to triple by using half the water. In these hot, arid environments, this partial shade from solar panels can really have a beneficial effect on crop yields while reducing water demand.

But the results seen at Maine Blueberry match what NREL has seen in the Northeast.

“In a place like Massachusetts which is much cooler and more humid, you see much more mixed results,” Macknick said. “Some crops see a reduction in yield – you might see a 30% reduction for broccoli because it’s a crop that wants more sun than it gets.”

Farmers may be able to tolerate drops in production due to the extra income they get from solar energy.

“It always has to make economic sense,” for both the farmer and the solar developer, Macknick said. “Currently, the amount of revenue a landowner could get from having solar panels on an acre of land could be orders of magnitude greater than they would get from just growing crops.”

Hopes for the future

Robertson-Dubois said interest in agrivoltaics in the United States “has changed dramatically in recent years. The United States as a whole is a decade or two behind Europe and Japan, where agrivoltaics has been part of their photovoltaics for decades now.

BlueWave has recently been bought by Axium Infrastructure, a large company with revolving interests across North America and headquarters in Canada and New York. So going forward, BlueWave will be able to not only develop, but also own projects, said Robertson-Dubois, who wants “the opportunity to have that long-term relationship with the farmer and the landowner. , making sure we are doing a great job protecting soils, and also being more involved in the operation, maintenance and management of a project.

He said BlueWave is exploring new projects that co-locate solar energy with different types of agriculture.

“We look at everything from orchard crops like potatoes to potatoes to grazing systems to hay and forage,” he said. “I’m working on an early-stage hybrid system that can hold corn in the field. This farmer makes corn and hay and alternates between fields over time. We give up a little [cultivation space] in the field for solar potential, but we can install this combine and even potentially manure sprayers. It’s hard to come up with these designs, but I’m confident that over the next five to 10 years we’ll see solar deployment on types of agricultural crops that no one would have imagined a few years ago.

Sweetland, like Calderwood, observed that since solar construction, blueberries do not grow as tall or produce as many stems as they normally would. Nevertheless, he hopes that dual-purpose agrovoltaics could work.

“I expect we’ll get some good growth of new stems next year, and the year after that when they flower, hopefully we’ll be back on track,” said Sweetland, who has worked in the local blueberry fields since the age of eight. . “We need energy; we also have to feed ourselves. If we can make it so that we get a dual purpose from the earth, then we should take advantage of it. I sort of look at it like my whole life has been changing all the time – it’s part of our purpose in life… to keep up with the changes.

Edward N. Arrington