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Double up on land use to maximise resources

For years, farmers had to decide to stick with their traditional produce or twist and turnover their land for renewables projects. Until recently, it has not been a financially viable option for agriculture and solar panels to live side by side. But new techniques are providing a chance to use increasingly scarce land more efficiently

Combining solar power production and agriculture can help increase the efficient use of land


TECHNICAL DEVELOPMENT
New solar panel technologies means larger units that follow the sun’s movement can be used to free up space for large farming machinery

LAND ARGUMENT At a time of energy and food security issues, combining agriculture with energy production solves the battle over land use

KEY QUOTE
It’s a bid to solve the conflict around the [use of] open land, which we would all like to use for different purposes


One of the Technical University of Denmark’s (DTU) test facilities at Research Center Risø, north of Roskilde, is dominated by shadow. The fixed solar photovoltaic (PV) panels, in lines running east-west, face south meaning the ground behind the panels is shaded for most of the time.

Meanwhile, the ground of the neighbouring test facility, still covered in solar panels, is flooded with sunlight. These rows of solar panels run north-south, providng more access for the sun. Also, there is more room between the rows—up to 15 metres compared with five metres at the first site. This frees up space for crops to grow or livestock to roam more freely.

The site is Denmark’s first Agri-PV facility and the researchers are obtaining promising results. With the right combination of technology, hours of daylight and produce, a new pathway to more efficient use of land emerges.

To make this set-up feasible, single-axled PV trackers are used, which follow the sun from its rise in the east until it sets in the west. These trackers used to be prohibitively expensive but, just like other renewables technologies, the price has dropped significantly in recent years. The price difference between the fixed and moving panels is €0.05 per kilowatt-hour.

Agri-PV is already taking off in Spain, Italy, Belgium and Germany, and its introduction in Denmark would be most welcome as the country tries to overcome a lack of space. It’s a bid to solve the conflict around the [use of] open land, which we would all like to use for different purposes,” says Uffe Jørgensen from the University of Aarhus and one of the associated researchers at the test facility.

He points to two arguments the use of Agri-PV techniques aim to solve. The first is a traditional criticism of solar power facilities: They take up space which could be used as important farmland to grow crops, especially during a time when food security is an issue due to the war in Ukraine.

The second argument was seen during the debate around the first generation of bioenergy. At that time, replacing agricultural land with bioenergy production—or solar panels, now—actually leads to more emissions. The lost agricultural production needs to be replaced elsewhere, leading to a loss of established wildlife habitats. Scientists call this indirect land-use change.

You should look at solar power replacing agricultural land in the same way,” says Jørgensen. If there was a way to do both things at the same time it would be good. This is what we’re looking into. I’m all about win-win solutions when it comes to the green transition and I think we’re looking at one such solution here,” he adds.

Future vision Taller solar panels mean a greater distance can be left between rows, allowing agricultural vehicles to pass by


SMOOTH OUTPUT

Using the tracking solar panels has the added benefit of providing a more even energy output throughout the day because they follow the sun. Production from the standard fixed and south-turned panels peaks in the middle of the day when the energy need is the lowest. The smoother production of the tracking panels profile reduces the load on the transmission infrastructure.

Electricity demand is higher in the morning and the afternoon, which makes solar power more valuable. This partly makes up for the fact that you need around 20% more space to produce the same amount of electricity as a standard south-facing facility. The rest is made up for by the income from agricultural production.

Danish renewables developer European Energy, which is part of the team conducting the research at Risø, has previously implemented animal husbandry alongside fixed south-facing solar panels. This is the simplest form of Agri-PV with the added advantage that the livestock keeps the vegetation low, stopping any shade from covering the panels.

The company has had a keen focus on so-called co-location—the dual use of a plot of land. Just like its compatriot Better Energy, it has often thought about combining nature and biodiversity with solar power facilities. European Energy planted 245,000 trees around its facilities in 2021 alone.

In late November 2020, the developer turned on its first commercial solar facility with moving axles in Skive, Jutland. This initial project only comprised a single row of panels and was further limited due to local regulations that only allowed a maximum height of three meters.

To reach a level of commerciality, along with efficiently farmable land, the panels need to be higher, reaching around five meters when the panels are vertical. When we get to that height, the distance between the rows can be ten meters making it possible for modern agricultural equipment to drive through. That’s what we’re working on and we have quite a few project applications out but they require local regulations to be changed,” says Mads Lykke from European Energy.

An advantage is that looking at it you’ll see more field and fewer solar panels due to the ten meters between the rows,” Lykke adds. The three-metre height restriction limits the energy yield, Lykke explains. As it is, energy production is a lot more profitable than agricultural production. We have to sell the electricity on the European market which makes it hard to be competitive with a lower energy output per hectare. With the taller facilities we can make the ends meet,” he says.

SHADE OR WIND

One of those introducing Agri-PV to Denmark is Jørn Rosager from Spanish solar company Powertis, a subsidiary of Soltec Power. Before entering the PV industry, Rosager worked in the agriculture sector. This means he understands why many farmers are reluctant to give up actual farming for energy production. He also has a farmer’s knowledge about the need for sun and the number of sunny days the crops require for a healthy yield.

Agri-PV solutions may look different in other parts of the world. In Southern Europe and other areas close to the equator, the sun’s intensity means farmers need the shade north European farmers try to avoid. This need has traditionally been solved by planting trees, leading to the term Agroforestry. But trees can end up stealing water from the soil. Solar panels, meanwhile, would not use up valuable moisture. I call it high-tech agroforestry”, says Jørgensen.

Elsewhere, in places like southern India and California the sun is so intense that the water in rivers and irrigation channels evaporates. Here local authorities have successfully installed solar panels on top of the waterways and reservoirs.

Back in northern Europe, and like many areas around the world, farmers combat another force of nature: gale-force winds. For centuries farmers have planted windbreaks between their fields. Jørgensen and the team at Aarhus University are convinced that these, like the shade-giving trees, can be swapped out with vertical rows of solar panels. In spring 2022, a test windbreak was installed in cooperation with a blueberry grower in Skælskør, east Denmark.

At what point Agri-PV unleashes its true potential depends on both developers and the political flexibility at the national and local levels. As with much of the renewables sector, the red tape needs to be removed and height regulations need to be loosened.

But there are signs that the national politicians are moving fast in light of the war in Ukraine, which has led to both higher prices for energy and food: the municipality of Randers in west Denmark signalled that it would demand Agri-PV for a large number of new applications for solar energy parks. •


TEXT Rasmus Thirup Beck PHOTO European Energy Visualisation KirtThomsen for European Energy