Renewables, Solar

Farming the sun and land: The power of agrivoltaics

Rural communities will feel better about the rollout of utility-scale solar if developers and landowners favour dual-purpose deals, writes Jeremy Chunn.

Ben Wynn from solar development company Wynergy says it would be nice if many solar farmers got out of the city from time to time and spent more time with their rural counterparts. “You’d see a reduction in land-use conflict [and the perception that] solar farmers are coming in and taking large swathes of agricultural land,” he says.

Wynn is based in Tamworth, NSW – a part of the state that will be transformed as renewables projects are built to replace ageing coal generators. He says Wynergy advocates for “agrivoltaics” – PV systems designed to operate on land used for grazing sheep or horticulture.

Based on research Wynn’s seen from the US and Europe, a solar farm designed using agrivoltaic principles will experience more than a 300 per cent increase in soil moisture retention thanks to reduced evaporation and exposure to wind.

“With that additional soil moisture, we see about a 90 per cent increase in pasture yield,” he says.

Farmers in Japan, Germany and the US are leading the field in pairing solar with horticulture, says NSW farmer and renewables advocate Karin Stark. An agrivoltaics trial at a tomato farm in the US state of Arizona has seen a doubling in yields.

“Tomatoes can’t process all the sun they get in a day so shade can be quite beneficial, and it reduces the need for irrigation,” Stark tells EcoGeneration.

As the solar build-out continues across Renewable Energy Zones where agriculture is the leading sector, it will be important for developers to listen to communities and farmers. It’s hardly surprising if locals start to fear the future when they see farmland locked up in 25-year solar leases. However, that attitude would change if the land had dual use.

Agrivoltaics can give rural land an efficient dual purpose. Photo: Shutterstock.

The mowing crew

Sheep were quick to help the solar cause in Australia. Woolly ovines have been keeping the grass down at the 20MW Royalla Solar Farm in the ACT since 2015. But developers and landowners have become more sheepish since then. In its 2021 report on “agrisolar”, the Clean Energy Council reckoned 14 large-scale solar plants (5MW and above) doubled as sheep farms in 2020.

The trend continues: on the NSW-ACT border, the 120MW Wallaroo Solar Farm plans to also operate as a 163-hectare sheep farm, with natives planted to attract bees; and plans for the 520MW Goulburn River Solar Farm in NSW include around 1000 sheep grazing beneath bifacial PV arrays standing five metres aboveground.

Landholders approached by solar developers always have the option to continue farming. Near Stark’s wheat, cotton and barley farm in Narromine, farmer Tom Warren, from Dubbo, is grazing sheep beneath an 18MW solar farm. He’s happy because his flock yields more wool, and the plant owner is happy because grazing keeps the grass down, meaning less money is spent on chemicals.

A solar developer could expect to negotiate competitive terms with a farmer still working the land beneath the panels, which includes vegetation management. “The landholder, in return, gets to earn income – whether it’s drought years or not – but continues to make agricultural income off that same land,” says Wynn. “It’s a win-win.”

During a two-year drought, Warren’s sheep mostly got by on strips of grass that survived on condensation that trickled from tilted panels overnight. Where some sheep farmers were handfeeding for 18 months, Warren only needed to for three months.

Ticking boxes

Large-scale solar is not a large-scale threat to prime agricultural land, says Shane Melotte from Energy Forms, a company that helps developers find locations for large-scale projects and navigate the approvals process.

“You get caught in a position where you’re trying to locate projects on the absolute lowest-quality agricultural land, not have any environmental impacts, and still be in a position where there is capacity in the grid,” he says.

Until the National Energy Market is upgraded to support connection of new renewables, suitable locations are becoming harder to find. Melotte says a shift to solar farms doubling as working farms is underway.

“Developers are having those conversations with landowners, and landowners are retaining the right to do that kind of activity between the rows of panels when they do their lease agreements,” he says.

In NSW, various mapping systems used to classify land for mining and resources exploration, or as biophysical strategic agricultural land, are being replaced by an all-inclusive system, but Stark wonders how accurate it will be in identifying high-value agricultural land.

“Developers who want to put in a solar farm should also go to the local community to understand the value of that land,” she says, because mapping data might not reveal all the economic contributions of land to farmers and the community. “It’s really important locals understand the perception of what the value of the land is.”

2P or not 2P

Wynn says the trick to farming the land and sun at the same time is to use a 2P orientation – two rows of panels stacked in portrait – with trackers that are about 12 metres apart and about 2.2 metres aboveground at the point of rotation, and offer about 600mm ground clearance when facing east or west.

“Having that row width of 12 metres means you’ve got a lot more agricultural functionality to get down that row and do what you need to do as a farmer,” he says.

Sheep and poultry are short enough to do no harm to panels, however cattle and PV are not a good mix. Some farmers have beehives positioned among solar arrays, and one owner in Werris Creek, NSW, is planning to harvest hay between rows of PV.

“It would be great if 2Ps were a favoured system, or if the government regulated that prime agricultural land had to be continued for use,” says Wynn. “You’d see a big reduction in the land-use conflict.”

The higher and wider-apart 2P format only accounts for about 10 per cent of large-scale solar plants and projects. The other 90 per cent is 1P, about 1.2 metres to 1.5 metres aboveground along the axis, with 6.5 metres between rows. A farmer can’t really do much with strips of land that narrow, says Wynn, “and then you’ve got to spend hundreds of thousands a year on mowing.”

Nextracker’s distributed PV tracking system, with all mechanics about 1.5 metres aboveground, have been installed at some sites around Australia where sheep are left to roam among the arrays, happily eating grass. The company has proposed 2P tracking for some utility-scale projects where crops are planned, although Nextracker vice-president Australia Peter Weale tells EcoGeneration its 1P format would also work.

“We have designed a few of these systems with agriculture underneath,” he says. “It would work on either technology [1P or 2P].”

Sheep seeking shade from solar panels on a dual-purpose farm. Photo: Shutterstock.

Vegetation on solar farms

Cropping beneath solar isn’t as straightforward as grazing. High-value crops such as blueberries, tomatoes and celery benefit from shade, says Stark, and solar could benefit vineyards.

“Having solar panels provide part-shade can be very positive,” she says, pointing to a trial by Agriculture Victoria at an orchard in Goulburn Valley, where panels will be installed above pear trees. At the operational 34MW Cohuna Solar Farm in Victoria, low-lying pastures and crops are being considered.

The extra cost of designing and building a PV plant that suits horticulture may be enough to turn off some developers. Cropping increases the risk of fire at a PV plant, but that doesn’t mean it can’t be done successfully.

“With social licence being such a massive risk to some of these developments in some of these regional communities that have agriculture at their heart, it’s really important we at least try,” says Stark.

High-value agricultural land needn’t be sacrificed to renewables, but developments should always be assessed for dual-use. It could be as simple as planting wildflowers between arrays, as some farmers in the US are doing, to attract bees that pollinate 70 per cent of food crops.

Stark’s message to solar developers is simple: “People in rural Australia are attached to and identify with the rural landscape,” she says. “If developers want to build a project that won’t attract much opposition, they’ve got to start thinking about ways farming can continue between solar panels.”

If agriculture and energy are seen to be working together, rural communities and peak bodies can move in the same direction. In her role as an agrivoltaics advocate, Stark is working on the third National Renewables in Agriculture Conference and Expo, planned for 18 August, 2022, in Albury, NSW.

The main focus is farmers using clean energy solutions to replace diesel, but some speakers are there to explain the opportunities that large-scale renewables projects can offer landowners and communities.

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