How your solar panels attach to your roof affects the cost, the look and, to a small degree, the performance of your system. There are two main approaches: on-roof and in-roof. This guide explains the difference, weighs up the pros and cons, and helps you pick the right mounting for your roof type. When you know what you need, you can find the kit in our solar mounting hardware range or request a mounting quote.
On-roof vs in-roof: the quick answer
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On-roof (mounted) |
In-roof (integrated) |
|
|---|---|---|
|
How it fits |
Panels sit on brackets above your existing tiles |
Panels replace a section of tiles and sit flush |
|
Cost |
Lower, most cost-effective |
Higher, more materials and labour |
|
Appearance |
Panels stand slightly proud of the roof |
Sleek, flush, built-in look |
|
Performance |
Slightly better cooling and airflow |
Runs marginally warmer |
|
Best for |
Retrofits and most existing roofs |
New builds, re-roofs, aesthetics-led projects |
If cost and simplicity matter most, on-roof usually wins. If you want the cleanest look, or you are building or re-roofing anyway, in-roof is worth the extra. The rest of this guide explains why.
What are in-roof (integrated) solar panels?
In-roof, or integrated, panels sit within the roof itself. Instead of resting on brackets above your tiles, they replace a section of the tiles and sit flush with the surrounding roof surface on a weatherproof tray or flashing system. The result is a smooth, built-in appearance that many homeowners prefer.
Pros and cons of in-roof
Advantages:
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The neatest, most discreet finish, which suits period properties, new builds and design-led projects.
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No tiles underneath the array, so you are not paying for tiles you cover up on a new build or re-roof.
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Often favoured where planning or aesthetics are a priority.
Trade-offs:
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Higher cost, because the tray or integration system and the labour add up.
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Panels can run marginally warmer with less air behind them, which slightly reduces output compared with on-roof.
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Access to an individual panel is more involved if one ever needs replacing.
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Weatherproofing relies on the integration system being fitted correctly, so quality of install matters.
You can see the panels and kits suited to this approach in our in-roof solar panels collection and in-roof mounting kits.
What is on-roof (mounted) solar?
On-roof mounting is the most common approach in the UK. The panels sit on rails held a few centimetres above your existing tiles by roof hooks or brackets. Your tiles stay in place, and the panels sit on top.
Pros and cons of on-roof
Advantages:
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Lower cost, which makes it the most popular choice for retrofits.
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The air gap behind the panels helps them run cooler, which gives slightly better output.
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Works on almost any existing roof, and individual panels are easy to access.
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Faster to install on a finished roof.
Trade-offs:
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The panels stand slightly proud of the roof rather than sitting flush, which is a less integrated look.
Browse the panels for this approach in our on-roof solar panels collection.
Which mounting suits your roof type?
Beyond the on-roof or in-roof choice, the right fixings depend on what your roof is made of. We stock mounting systems for all of the common types.
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Pitched tile or slate roofs. The most common UK roof. Roof hooks fix to the rafters and support the rails. This is standard on-roof territory.
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Flat roofs. Panels sit on a ballasted or A-frame system that tilts them to the right angle without penetrating the roof membrane. See our flat roof mounting.
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Metal, trapezoidal and corrugated roofs. Common on outbuildings, barns and commercial units, these use specific brackets designed for the profile of the sheet.
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Tile roofs specifically. For the right hooks and flashings, see our tile roof mounting.
Whatever your roof, the full range of rails, hooks, clamps and fixings is in our mounting hardware collection.
Getting the right mounting kit
Mounting is not the place to cut corners. It holds your panels securely through decades of wind and weather, and a poor fixing can damage both the panels and the roof. Match the mounting system to your roof type and your panels, and use components designed to work together.
If you are unsure what your roof needs, request a mounting quote and we will specify the right system. Mounting is also covered as part of a full system, so if you are still planning your project, start with our home solar buyer's guide and get a quote.
Frequently asked questions
What is the difference between in-roof and on-roof solar? On-roof panels sit on brackets above your existing tiles. In-roof panels replace a section of tiles and sit flush with the roof for a built-in look.
Which is cheaper, on-roof or in-roof? On-roof is cheaper. It uses fewer materials and less labour, which is why it is the most popular choice for retrofitting an existing roof.
Do in-roof panels produce less electricity? Slightly. With less air behind them they can run a little warmer, which marginally reduces output compared with on-roof panels. For most homes the difference is small.
Can I retrofit in-roof panels, or is it only for new builds? You can retrofit in-roof, but it is most cost-effective on new builds and re-roofs, because the panels take the place of tiles you would otherwise buy and fit.
What mounting do I need for a flat roof? Flat roofs use a ballasted or A-frame system that tilts the panels to the right angle without penetrating the membrane. See our flat roof mounting.
Not sure which mounting suits your roof? Request a mounting quote and we will specify the right system.
