Large-scale solar installations are becoming popular in agriculture - but getting the right mix of crop and solar is hard.
An apple farm in western Germany is reaping a second harvest - but it's not what you might expect.
Solar panels providing much-needed shade for the orchard have been producing bountiful electricity during this year's unusually hot summer.
“The idea is simple,” says Christian Nachtwey, owner of the organic farm in Gelsdorf - an hour's drive south of Cologne.
“To protect the orchard, without reducing the available growing surface and in particular maintaining production. On top of that there's the solar electricity being generated on the same land.”
Solar installations provide farmers with a second source of revenue
Large-scale solar installations on arable land are becoming increasingly popular in Europe and North America. They allow farmers to make the most of their land and establish a second source of revenue.
Getting the right mix of crop and solar is hard though, because modern fruit varieties are finely tuned to particular growing conditions. Any change can tip the balance, costing farmers revenue if their fruit is damaged, the wrong colour or not as sweet as consumers like.
That's why Nachtwey is collaborating with researchers to test which apple varieties thrive under the solar canopy, and which types of photovoltaic roofs are best suited for the orchard. To compare the results, some trees are covered with a conventional netting normally used to protect sensitive crops from hail.
German researchers are investigating how solar panels impact crop outcomes
Juergen Zimmer, an expert with the agricultural services department of Rhineland-Palatinate state, says the apples grown under the solar roofs were slightly less sweet this year than those under the hail nets.
But hardly any of the solar-shaded apples got damaged in the intense sunlight that hit the region on 24 July this year. By comparison, up to 18 per cent of the uncovered fruit suffered sunburn that day.
“We need at least two-to-three full years to record all the weather conditions that might occur, and look at the yield and colour that the different varieties of tree produce," says Zimmer.
Researchers hope the tests will show that tree fruit crops thrive under solar panels. This could help prevent renewable energy production from competing for precious land with agriculture - a growing concern for those seeking to tackle climate change and rising food prices.
Nachtwey says he could use the solar electricity generated on the farm to power his own facilities and machines. But to start with, he plans to provide the electricity to dozens of nearby homes instead.