A meadow pipit at the solar park on peatland in northern Germany
Wattmanufactur
A solar farm on a rewetted peatland is home to more types of bird than drained agricultural fields nearby, suggesting that land used for renewable energy can make money for landowners, lock away carbon and boost biodiversity at the same time.
Peatlands are the largest terrestrial carbon store, holding twice as much carbon as all forests. But enormous tracts of them have been drained to create farm fields or dug up to produce potting soil for gardening. Ninety-five per cent of peatlands in Germany and 80 per cent in the UK have been degraded.
Once farmers drain a peatland with ditches and pumps, microbes begin breaking down the ancient carbon it holds, emitting carbon dioxide for decades or centuries.
A German state-funded research programme has begun looking at whether solar farms could help promote peatland restoration.
“We can’t simply just say, ‘Let’s just rewet it all and put it back to nature conservation’,” says Hanna Rae Martens at the University of Griefswald, Germany, who worked on the research. “There’s a lot of people on the land who are looking for income.”
At the study site, the solar company Wattmanufactur started building sand-and-gravel roads in 2020 that cut off the flow of water to existing drainage ditches, allowing the farm field to accumulate water and turn back into peatland.
The study was the first to look at the impacts of putting solar on rewetted peatland, and it found a benefit for biodiversity, according to Martens.
“A fear here is we destroy habitat, and in this case, it is not the case,” she says. “There’s habitat created for some species, and it’s being created for some endangered and some wetland species, and it has the potential to contribute to landscape-level diversity.”
Although species richness was about the same in the 30-hectare solar park and in two fields nearby that were regularly mown for hay, audio recorders showed the solar park had both wetland and woodland bird species, while the hay fields had only grassland species like the European goldfinch.
White wagtails, reed buntings and grey herons, all wetland species, were registered in the solar park, but so were woodland species like tree pipits and Eurasian tree sparrows. The solar panels seemed to be standing in for shrubs and small trees, with birds like buzzards and kestrels perching on them to hunt mice in the grass below.
Researchers also photographed the meadow pipit, a small, brown-streaked grassland species that is threatened in Germany, on the panels.
Martens thinks the rewetted peat, the solar panels for perching and the reduction in grass mowing all helped attract birds. But further research is needed to see how that biodiversity compares with that of rewetted peatland without solar panels, according to Catherine Waite at the University of Cambridge.
“Peatland PV [photovoltaics]… could be a really good way to kind of help regenerate heavily degraded agricultural peat, but that doesn’t mean it would also be a good thing to put it on really healthy peatlands elsewhere,” she says.
While the UK has restored 2500 square kilometres of peatland, that is only one-tenth of what has been damaged, and Germany has restored far less. Moreover, because the emissions from drained peat continue for many years, some of the 165 solar farms that have been put on degraded peatlands in Germany are actually releasing more greenhouse gases than they are displacing with their carbon-free energy.
Unlike agrovoltaics, where grazing or crop-growing continues around the solar panels, peatland PV doesn’t currently generate income beyond electricity sales. The Wattmanufactur solar park is one of only five on rewetted peatland. Solar developers on peatland often have to install deeper posts and wait until the dry summer period before starting construction, increasing costs.
Although Germany has barred solar farms on degraded peatland from receiving a minimum guaranteed electricity price since 2023, developers aren’t always forced to declare if their installation is on drained peat.
More government incentives are likely to be needed for peatland PV to really grow, says Waite. “If we want to deal with things like global warming and the biodiversity crisis, but also how to feed people, we have to manage land in a way that provides multiple benefits,” she says. “So we have to have these win-wins.”
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