Solar panels raised above crops: first results from an Asher Valley trial

On a south-facing slope outside Bramley Cross, rows of solar panels stand on steel legs nearly five metres tall. Beneath them, tractors pass easily between beds of potatoes, lettuce and raspberries. The site is one of the first agrivoltaic trials in the region, and after a full growing season the researchers running it have published their initial results.

The panels cover about a third of the sky above the crops and can tilt to let more light through during cloudy spells. Over the season the array generated 1.1 gigawatt hours of electricity, enough for around 300 homes, which is sold to the grid under a fixed-price agreement. Yields underneath varied sharply by crop.

• Lettuce yields rose 12 per cent, with less scorching in hot spells

Less water, more shade

The soil under the panels also stayed wetter. Irrigation on the shaded beds was cut by about a quarter during the dry weeks of the summer. Dr Simon Achebe, the agronomist at the University of Wrenhaven who leads the study, said the findings matched trials in hotter countries but were less certain in a cooler, cloudier climate.

The panels do not suit every crop, and the trick is choosing the ones that welcome a little shade.

The land belongs to Margaret Doyle, whose family has farmed near Bramley Cross for four generations. She said the rent from the solar operator now covers about a fifth of her farm's running costs and had made her more willing to experiment. Her main worry was the effect on soil during construction, which was limited by driving the legs into the ground rather than pouring concrete foundations.

The trial also tested how farm work fits around the steel structure. Rows were spaced nine metres apart so that a standard tractor and sprayer could pass, and the legs were placed along existing field drains. Harvesting the potatoes took about 10 per cent longer than in the open field, mostly because machinery had to turn more carefully at the end of each row.

Some farming groups remain cautious. The Asher Valley Growers' Cooperative has said solar should not take good land out of food production. The researchers plan two more seasons of trials and will add beans and blackcurrants next year.