The on-roof system – modules on a frame above the existing roof covering – is the standard and the cheaper option. The in-roof system replaces the roof skin and is integrated flush; it looks better, but costs noticeably more per kilowatt-peak, because more work and special material are needed. The extra cost is worthwhile above all when the roof is being re-covered anyway or when appearance is a real criterion – for a pure retrofit onto an intact roof, on-roof is almost always the right choice. (As of: July 2026)
Key points in brief
- On-roof is the standard and cheaper option – the modules sit on a frame above the roof covering.
- In-roof replaces the roof skin, looks calmer and flatter, but costs more per kWp.
- The extra cost comes from more installation work and special material, not from better modules.
- For new builds and roof renovations, the extra cost becomes relative, because in-roof replaces the roof covering.
- Retrofitted onto an intact roof, on-roof is as a rule the more economical choice.
What is the difference between roof-integrated and on-roof?
In short: the position of the modules relative to the roof skin. With the on-roof system, the existing roof covering stays in place, and the modules are mounted on a frame above it – by far the most common design. With the in-roof system, the modules are integrated into the roof surface and take over the function of the roof skin themselves; the tiles underneath are omitted, and the system sits flat and flush in the surface.
The technology behind it is explained in detail in the article In-roof photovoltaics. For the cost question, one thing matters above all: in-roof is not «better modules», but a different installation method – and this installation method is more elaborate.
Why does in-roof cost more?
The extra cost doesn't arise from the modules, but from the work and the special material. An in-roof system has to take on the roof skin's tasks: it has to be watertight, keep out wind and water, and connect cleanly at edges, the ridge and penetrations. That requires a suitable in-roof system, more care during installation and more time on the roof – and that is exactly what shows up in the price per kilowatt-peak.
How the price per kWp is made up in the first place, and why it's the fair basis for comparing quotes, is shown in the article Cost per kWp. The in-roof design is one of the factors there that push the kWp price upward – alongside storage, system size and module class.
On top of that, there's a point that's often overlooked: on an intact tiled roof, in-roof replaces a covering that's actually still good – so you're throwing away usable material. That's rarely economically sensible. The case is different when the roof is due for replacement anyway.
| Criterion | On-roof | In-roof |
|---|---|---|
| Price per kWp | lower (standard) | higher (more work + special material) |
| Appearance | Modules visible above the covering | flat, flush, calmer |
| Ideal for | Retrofitting onto an intact roof | New build, roof renovation, appearance requirements |
| Roof covering | stays in place | is replaced (tiles are omitted) |
Simplified overview, as of July 2026. The specific surcharge depends on the roof, system and project – the individual quote is decisive.
When is the extra cost for in-roof worth it?
It comes down to exactly two situations: new build/renovation and appearance.
If the roof is going to be re-covered anyway – for a new build or during a roof renovation – the extra cost becomes considerably more relative. Because in-roof replaces the roof covering that you would otherwise pay for separately. You're then not comparing «on-roof versus in-roof», but «new tiles plus on-roof system» against «in-roof system as the roof skin». In this calculation the gap shrinks, and in-roof becomes a serious option.
The second criterion is appearance. For anyone who wants a flat, calm roof surface – for design reasons, or because the municipality values it for protected buildings and in core zones – the extra cost is a deliberate design decision, not a bad purchase.
Conversely: retrofitting a system onto an intact roof that will still last another twenty years is the classic case for on-roof. The extra cost for in-roof wouldn't bring any equivalent value here – the existing covering would be the loss. As with every one of these questions: quality is decided less by the design than by the mounting system and how cleanly it's installed.
The in-roof question almost always comes up because of appearance – «the on-roof modules stick out too much for me». Our first question back is then never technical, but about timing: «How old is your roof?» Because the whole calculation depends on that. For a roof that needs replacing in the next few years anyway, we seriously work through the in-roof option – there it replaces the covering and the extra cost becomes relative. For an intact roof, we advise on-roof in most cases and say openly that the visual gain rarely outweighs the extra cost. What we never do: sell in-roof as «the better system» – it's the more attractive installation method, not the more productive one.
Frequently asked questions
Is in-roof or on-roof cheaper?
On-roof is cheaper and the standard – the modules sit on a frame above the existing covering. In-roof costs more per kilowatt-peak because it replaces the roof skin and needs more work and special material for that. The gap only becomes relative if the roof is being re-covered anyway.
Does an in-roof system produce less electricity?
Due to the design, rear ventilation can be tighter with in-roof, which can have a minimal effect on the modules in heat – but the difference isn't a purchasing criterion. You choose in-roof for appearance and roof integration, not for more or less yield. For the yield question, orientation and shading are far more important.
Is in-roof worthwhile during a roof renovation?
That's when it's most worthwhile. If the roof is being re-covered anyway, the in-roof system replaces the roof covering that you would otherwise pay for separately – the extra cost shrinks accordingly. You then compare «new tiles plus on-roof» against «in-roof as the roof skin». The article on roof renovation goes into this combined calculation.
Why shouldn't I choose in-roof on a good roof?
Because in-roof replaces the roof covering – so on an intact roof you would be removing usable material and paying for it. The visual gain rarely outweighs this loss. On a good roof, on-roof is almost always the more economical choice; in-roof plays to its strength in new builds and renovations.
Free initial consultation
In-roof or on-roof – we calculate it honestly.
We look first at your roof and its age, then at appearance – and say openly when the in-roof extra cost brings equivalent value and when it doesn't.
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Swissolar-certified specialist company · ESTI installation authorisation (Art. 14 NIV) · in Zurich since 2017 · over 150 systems completed · a personal answer from the specialist company, no call centre
Sources: Experience from in-roof and on-roof projects by ecoEn GmbH (Zurich region), Swissolar technical information, mounting system manufacturer specifications.
Last updated: 9 July 2026 · Author: ecoEn editorial team
