In-Roof & Flush Solar

An in-roof system replaces a section of tiles with a purpose-made tray. The tray carries the panels and channels water around them, while a neat flashing kit frames the edges. The modules sit flush with the roof, with no rails or hooks.

The result is a calmer roofline. While a typical on-roof job shows deep shadow gaps and visible brackets, an in-roof array reads as a recessed dark rectangle. It does not float above the tiles.

Many owners are weighing the two approaches. Our comparison of in-roof and on-roof solar panels on looks, cost and performance is a good place to start, because it sets them side by side.

In-roof solar sits between on-roof panels and full solar tiles. It uses standard, high-output modules, because that keeps much of the economy of conventional panels. At the same time it delivers much of the flush look that makes solar tiles desirable.

That balance is the sweet spot for many self-builders and re-roofing owners, because the roof looks contemporary and the cost stays sensible. It is a compromise, but a good one.

Because the tray becomes part of the weathering, detail matters. Systems differ in how they flash, drain and fix to the rafters. Our review of in-roof solar mounting systems compared sets out those differences.

The module matters as much as the tray. A full-black panel with dark cells and a dark frame disappears best, because nothing catches the eye. Our note on when an all-black solar panel is worth it explains the trade-offs.

An in-roof array follows the same physics as any other solar. Direction, pitch and shade set the output. A clear south-facing pitch usually works best in the UK, although east and west roofs can still pay their way.

The flush finish adds one more point. Air flow behind an in-roof array can differ from air flow behind raised panels. We therefore follow the maker's guidance and plan the layout with care.

We also look at the whole roof, not just the array. Edges, flashings and the join with the old covering all show. If they look untidy, the flush effect is lost, so we draw each junction before the roofer starts.

A clean finish also depends on good set-out. We centre the array on the roof where we can, and we keep the margins to ridge, eaves and verge even. In practice, an even margin is what makes a flush array look intended.

We choose the tray and flashing to suit the covering and pitch. Then we set the array out so the margins stay even against ridges and verges. We also coordinate with the roofer, because the interface has to be right first time.

On new builds we detail the in-roof zone into the roof design from the start. On re-roofs we integrate it as the covering is replaced. That avoids disturbing a finished roof later, since the work is done once.

The approach travels well. In an Oxford terrace, in-roof solar for Oxford homes keeps the street view tidy, while on a Cotswold farmhouse flush solar for Cotswold roofs sits quietly among older stonework. To discuss your own roof, use the enquiry form.