On-roof – modules on an existing roof – is by far the most common type of installation in the whole of Switzerland. However, the extent to which roof-integrated (in-roof) systems account for the total differs significantly between the cantons: from around 3 per cent in Ticino to over 29 per cent in Appenzell Innerrhoden. The basis is an evaluation of the public SFOE installation register. (As of: register data August 2026)
Key points in brief
- According to the publicly available register data, on-roof installation is the most common design in every canton – in-roof remains in the minority everywhere.
- The in-roof share fluctuates strongly between the cantons: from around 3% (Ticino) to over 29% (Appenzell Innerrhoden).
- The register shows the mounting type via the field categories on-roof, in-roof and free-standing, not via a separate federal "in-roof rate" statistic.
- A high in-roof share can't be explained by aesthetics alone – regional building regulations and roof types also play a role.
What is the difference between on-roof and in-roof – and how is this recorded?
With an on-roof system, the modules are mounted on an existing, unchanged roof. With an in-roof system, the modules replace the roof covering itself and form the water-bearing layer. The SFOE plant register records this distinction directly as a field per system – together with a third category for free-standing systems.
How much does the in-roof share differ between cantons?
| Canton | Roof-integrated share |
|---|---|
| Appenzell Innerrhoden | 29,1 % |
| Graubünden | 27,5 % |
| Glarus | 27,0 % |
| Wallis | 22,9 % |
| Obwalden | 22,4 % |
| Bern | 18,8 % |
| Waadt | 20,3 % |
| Schwyz | 16,7 % |
| Appenzell Ausserrhoden | 16,0 % |
| Basel-Stadt | 14,6 % |
| Zurich | 11,6 % |
| Neuenburg | 10,6 % |
| St. Gallen | 10,3 % |
| Freiburg | 10,3 % |
| Nidwalden | 15,5 % |
| Luzern | 8,6 % |
| Genf | 7,8 % |
| Solothurn | 8,1 % |
| Zug | 7,3 % |
| Aargau | 6,8 % |
| Basel-Landschaft | 6,8 % |
| Uri | 6,2 % |
| Schaffhausen | 5,8 % |
| Thurgau | 5,6 % |
| Jura | 5,6 % |
| Tessin | 2,8 % |
| Switzerland overall | 12,7 % |
Source: SFOE plant register «Electricity production plants» (data.geo.admin.ch), register status August 2026. It is striking that the cantons with the highest in-roof share (Appenzell Innerrhoden, Graubünden, Glarus) are rather rural-alpine in character, while large, economically strong cantons such as Zurich, Aargau and Zug show a below-average in-roof share.
What does this mean for one's own planning?
The nationwide in-roof share of roughly 12.7% shows: even though in-roof systems convince visually, on-roof remains the standard solution in every canton – mostly for cost reasons with pure retrofits. In-roof is worth considering above all when a roof renovation is due anyway.
In our own, much smaller project portfolio the in-roof share, at roughly 25%, is above the cantonal Zurich average of 11.6% – this is probably also because in-roof projects offer disproportionately much to talk about in consultations and get documented, not because our portfolio is representative of the canton.
Frequently asked questions
Is in-roof even common in Switzerland?
Yes, but as a clear minority: nationwide the share is roughly 12.7%, with cantonal differences from under 3% to over 29%.
Why is the in-roof share higher in rural-alpine cantons?
That can't be conclusively clarified from the register data alone. Possible links are roof types, local building regulations or the share of new buildings.
Is a high in-roof share automatically to be seen as positive?
Not necessarily. In-roof is usually more expensive than on-roof and pays off above all when a roof renovation is due anyway.
Where exactly do these percentages come from?
From the public SFOE plant register «Electricity production plants», which records the mounting type per system.
In-roof or on-roof for your roof?
We advise honestly when an in-roof solution pays off – and when on-roof is the more economical choice.
Sources: SFOE plant register «Electricity production plants» (data.geo.admin.ch, register status August 2026).
Last updated: 18 September 2026 · Contact for questions on methodology: ecoEn editorial team
