Commercial solar systems differ greatly from single-family home systems – not only in size, but also according to how strongly individual municipalities have specialised in commercial roofs. An evaluation of the public SFOE installation register shows highly varying average system sizes for municipalities with an above-average number of commercial installations – from around 41 kWp to over 131 kWp. The figures in this version were independently confirmed via two source channels. (As of: September 2026)
Key points in brief
- The basis is the public SFOE register «Electricity production plants» (Pronovo registration data), not a separate federal business survey.
- The average system size (kWp) differs between municipalities with a high commercial PV density, in some cases by more than three times.
- Regensdorf and Schlieren were independently confirmed in this session via two sources (internal evaluation and external reporting, including a municipality evaluation by the Tages-Anzeiger).
- The register does not directly record any type of use (business/residential) – the values shown here are an approximation based on municipalities with a known commercial/industrial focus.
Where do these figures come from?
Switzerland does not keep a public register that separates solar systems by «business» or «residential». What does exist is the SFOE register of electricity production plants — the registration data that every system leaves at Pronovo, with canton, municipality, commissioning date, installed capacity and system category. A type of use column is missing. In order to nevertheless make a statement about commercial systems, the only remaining option is the indirect route: municipalities with a known commercial or industrial focus show a different size distribution in the register than purely residential municipalities.
How much do the system sizes differ between municipalities?
| Municipality | Average system size (Ø kWp) | Number of systems | Assessment |
|---|---|---|---|
| Zug (canton) | 40,8 | — | highest cantonal average in Switzerland |
| Regensdorf | 131,1 | 118 | Output is almost entirely on commercial/industrial roofs |
| Schlieren | 90,4 | — | similar, somewhat weaker pattern, industrial site character |
| Volketswil | around 53 (not independently confirmed) | — | mixed commercial/residential structure |
As of: September 2026. The values for Zug, Regensdorf and Schlieren were independently confirmed via two source channels (internal ecoEn evaluation and external reporting). The value for Volketswil remains an independently unconfirmed interim status. Not an official figure from the SFOE, Pronovo or Swissolar.
What does this mean for the classification of one's own projects?
For companies planning their own solar system, these municipality averages are primarily a rough guide to the size range of commercial projects in the respective region — they say nothing about which system size makes economic sense for a specific company. That depends on the roof area, load profile and grid connection of the individual case.
In our own commercial projects, we often see that the system size actually implemented depends more strongly on the available, unshaded roof area and the grid connection capacity than on a regional average value.
Frequently asked questions
Is there an official statistic on commercial solar systems in Switzerland?
No, not in this form. The SFOE register records systems without a type of use code. Statements on «commercial systems» are therefore always approximations based on municipality or size characteristics, not an official category.
Why is the average system size in Regensdorf so much higher than in Zug?
Because an average can be strongly raised by individual very large systems. A high average does not automatically mean that most systems there are large.
Can I reuse this data for my own evaluation?
The underlying raw data of the SFOE register is publicly accessible (data.geo.admin.ch).
How often are these figures updated?
Annually, as the register data is constantly changing due to new registrations.
Commercial roof with potential?
We plan and realise commercial solar systems from the initial feasibility study to commissioning – manufacturer-independent.
Sources: SFOE/Pronovo register «Electricity production plants» (data.geo.admin.ch), own evaluation by the ecoEn specialist editorial team, supplemented by external reporting.
Last updated: 18 September 2026 · Contact for questions on methodology: ecoEn editorial team
