In-roof solar panels: when they make sense and how they're fitted

In-roof solar panels replace a section of your roof tiles rather than sitting on top of them. The panels and a watertight flashing kit become part of the roof covering itself, so the array sits flush with the slope instead of standing a few inches proud of it.

That's the whole appeal, and the whole trade-off. It looks tidier, particularly from the street, but it needs more work to fit and it only makes sense on certain roofs.

What's the difference between in-roof and on-roof solar?

On-roof (sometimes called "on top" or rack-mounted) is the standard approach: your existing tiles stay where they are, and the panels are fixed above them on rails bolted to the rafters. It's quicker to fit, works on almost any pitched roof, and is what most of our published guide prices are built around.

In-roof removes the tiles in the area the array will cover and fits the panels into that gap, with flashing kits sealing the edges against the surrounding tiles. The panels sit at roughly the same depth as the tile course around them. You lose the visible aluminium frame and the gap underneath, and you gain a roof that reads as one surface rather than panels plus roof.

When does in-roof actually make sense?

There are three situations where it's worth the extra cost:

You're re-roofing anyway. If the tiles are coming off regardless, the extra labour to fit an in-roof system instead of retiling and then bolting panels on top is smaller than doing the two jobs separately.

It's a new build. The roof covering hasn't gone on yet, so the in-roof array can be specified as part of the roof design from the start, rather than retrofitted to a finished one.

You're in a conservation area or on a prominent roof slope that faces the street. Planning authorities and neighbours tend to object less to a flush array than to panels standing proud on rails, even where permitted development rights would technically allow the on-roof version. It isn't a guarantee of approval, and a listed building needs listed building consent regardless of mounting type, but a flush roof is a stronger starting point for that conversation.

Outside those three, on-roof is usually the more sensible choice. Fitting an in-roof system to an existing, otherwise sound roof covering means disturbing good tiles to create the gap, which costs more for a result that's mostly aesthetic.

Will I need planning permission in a conservation area?

Often not, but check before assuming either way. Solar panels on houses are commonly permitted development under Part 14 of Schedule 2 to the General Permitted Development Order, which means no planning application in many cases. Conservation areas, National Parks and similar designated areas carry tighter conditions on that right, particularly for anything on a roof slope or wall facing a highway, and some local authorities have withdrawn the right entirely in specific streets through an Article 4 direction.

We check this as part of the survey and tell you plainly if your property needs an application rather than falling under permitted development. It depends on the local authority, the designation, and which slope the array sits on, so we don't give a yes or no until we've looked at your address specifically.

How is an in-roof system fitted?

The roofer strips the tiles from the section the array will occupy, down to the battens and membrane, and checks the structure underneath is sound before anything goes back on. The in-roof kit then fits into that space: a mounting frame fixes to the rafters or battens, the panels sit into the frame, and flashing pieces seal the join between the panel edges and the surrounding tiles. GSE and Viridian are two of the manufacturers who make these kits.

The electrical side is the same as any solar install from that point: the panels wire into the inverter, the inverter connects to your consumer unit, and the system gets commissioned and registered the same way an on-roof array does.

What does the survey check?

The same things as any solar survey, plus a look at the roof covering itself: what the existing tiles are and whether a flashing kit is available to match or run alongside them, the roof structure's condition now the tiles will come off a section of it, orientation and shading as usual, and (for a conservation area or a street-facing slope) whether the local authority needs an application before work starts.

A roof with only a few years of life left should have that dealt with before any panels, in-roof or on-roof, go anywhere near it. There's no point fitting panels into tiles that need replacing again shortly after.

What does an in-roof system cost?

We don't publish an in-roof price. It's priced in writing after the survey, because the figure depends on the roof covering you have, how much of it needs to come out, which flashing kit fits your tiles, and the array size itself. Our published guide prices cover standard on-roof systems; in-roof is quoted for your roof specifically.

If the roof covering itself needs attention first, that's a separate conversation with our roofing team, who can tell you whether it's worth dealing with before any panels go on.

We're Flexi-Orb certified and an HIES member for the solar and battery side of what we do. Every system, in-roof or on-roof, comes with a workmanship guarantee from us, a manufacturer's guarantee on the panels, and the same monitoring app and paperwork handover as our standard installs.

If re-roofing, a new build, or a street-facing slope in a conservation area describes your situation, it's worth a free survey so we can look at your roof and tell you plainly whether in-roof is worth the extra cost, or whether on-roof gets you the same result for less.