The Swiss Federal Office of Energy (SFOE) puts the technically usable solar potential of suitable Swiss roofs at around 53.6 terawatt-hours per year – calculated on the basis of roof data from sonnendach.ch. Actual photovoltaic production was around 8.1 TWh in 2025. In purely mathematical terms, a good 15 per cent of the technical roof potential has therefore been exploited. (As of: September 2026)
Key points in brief
- sonnendach.ch is an official joint project by the SFOE, MeteoSwiss and swisstopo and shows the solar suitability of practically every Swiss building.
- Based on this data, the SFOE estimates the technical potential of good to very well suited roofs at around 53.6 TWh per year.
- Actual photovoltaic production in 2025 was around 8.1 TWh – the «exploitation rate» of around 15% is our own calculation, not an official key figure.
- The potential relates only to roof areas – facades and open spaces are not included.
What exactly does sonnendach.ch show?
sonnendach.ch is an official, free online portal of the federal government that shows how well practically every property in Switzerland is suited for solar energy. It was set up as a joint project by the SFOE, MeteoSwiss and swisstopo as part of the Energy Strategy 2050.
How large is Switzerland's technical solar potential – and how much of it is exploited?
| Metric | Value | Source |
|---|---|---|
| Technical solar potential (roofs, well/very well suited) | around 53.6 TWh/year | SFOE, based on sonnendach.ch |
| Actual photovoltaic production 2025 | around 8.1 TWh | SFOE, electricity balance 2025 (provisional) |
| Mathematical exploitation | around 15% | own calculation ecoEn (8.1 / 53.6) |
As of: September 2026. The «mathematical exploitation» is an independent, transparent ratio calculation – not a key figure published by the SFOE or Swissolar.
What does an exploitation rate of around 15 per cent tell us – and what does it not?
A rate of around 15% shows that mathematically a large part of the technical roof potential is still unused. However, this is not synonymous with «85% of roofs are unused» – a large part of the remaining potential is distributed over many individual, smaller roofs. In addition, the 53.6 TWh figure refers exclusively to roof areas; facades, which have also been possible in the simplified notification procedure since 2026, are not included.
During consultations, we often see roofs that are shown on sonnendach.ch as being «well» or «very well» suited, but which have not yet been used due to reasons such as historic preservation or pending roof renovations.
Frequently asked questions
What exactly does «technical solar potential» mean?
It is the maximum possible electricity production if all roof areas classified as suitable were covered with solar modules – a theoretical upper limit, not a forecast of actual expansion.
Is the figure of 53.6 TWh a fixed, unchangeable value?
It is based on the current building stock and current assumptions about module technology and may change in future SFOE calculations.
Why is the exploitation «only» an independent calculation?
Because the SFOE and Swissolar have not yet put these two values in relation to each other, at least not in a form available to us.
Are facades included in Switzerland's solar potential?
No, the 53.6 TWh figure refers exclusively to roof areas.
How well is your own roof exploited?
We check without obligation what is technically and economically feasible on your specific roof.
Sources: Swiss Federal Office of Energy (SFOE), sonnendach.ch; SFOE electricity balance 2025 (provisional).
Last updated: 18 September 2026 · Contact for questions on methodology: ecoEn editorial team
