Commercial solar panels on a Chepstow farm

The farm is a working agricultural holding near Chepstow in Monmouthshire, with a range of steel-framed farm buildings on site. The main barn carries a large south-facing pitched roof, the kind of unbroken run of metal sheet that suits a rooftop array well, and it sits above the parts of the holding that draw power through the working day.

Farms carry a steady base load that most people never see: refrigeration, water pumping, workshop tools, lighting and welfare facilities that run whether the sun is out or not. Generating on the roof means a share of that demand comes from the building itself rather than off the grid, which is what made the barn worth the survey in the first place.

The starting point was the roof and the frame beneath it. Before any panels were specified, the barn's existing steel frame and purlins were checked by a structural engineer to confirm they could carry the extra load of a rooftop array, and both passed without any strengthening work needed. That check matters on an agricultural building, where roofs are built for weather rather than added weight.

The array was then set out across the barn roof as two matched sections, each a self-contained 8 kW system with its own inverter and generation meter, giving 16 kWp in total from 32 full-size panels on hanger-bolt mounts fixed through the sheet roof. Wiring the roof as two separate systems keeps each string at a sensible size for the pitch and orientation, and means the two halves can be read and maintained independently.

In a typical year the system is estimated to generate around 10,508 kWh. On a farm, much of that lands during the working day when pumps, refrigeration and tools are already running, so the electricity is used the moment it is made rather than bought back later. Over the array's 25-year life that is a long run of generation the farm is no longer paying the grid for, alongside roughly two tonnes of carbon kept out of the air each year.