In-roof, on-roof or ground-mount: choosing the right mounting

On-roof mounting

The most common approach: rails fixed to the rafters with panels sitting above the tiles. It's cost-effective, keeps the roof covering intact and leaves an air gap that helps panels run cooler and produce more.

The detail that matters is the fixing. Roof hooks must land on rafters, tiles must be dressed correctly and the array must be set back from the edges for wind loading.

In-roof mounting

In-roof systems replace the tiles, sitting flush with the roof line. They look far cleaner and are often preferred on new-builds or in conservation-sensitive areas, but the weatherproofing tray and flashing must be installed exactly to specification.

Ground and flat-roof mounting

Where roof space is limited or badly oriented, ground-mounted frames give you full control over tilt and azimuth. Flat commercial roofs typically use ballasted, non-penetrative frames set at 10 to 15 degrees in east-west or south-facing rows.

• Ground-mount: ideal tilt, easy cleaning, may need planning permission
• East-west flat roof: flatter generation curve, better for daytime demand
• Always check structural loading before ballasting a commercial roof