Short answer
When does the PV solar obligation apply in Valais?
In Valais, new buildings and extensions generally need at least 20 W of PV capacity per m² of energy reference area; more than 30 kW cannot be required. Removing a roof covering also triggers 20 W/m² and a maximum of 80% of the affected roof area. Roofs above 500 m² additionally follow a 25-year rule where solar irradiation is sufficient.
Important
As of 16 August 2026, the Valais solar obligation must not be confused with general exemption from building permits. A system can meet the energy requirement and still require separate assessment under building or heritage law. Conversely, a roof renovation does not trigger the obligation in every case: the cantonal energy portal expressly names GEAK class C, simultaneous facade renovation, renewal of only the north-facing roof and seasonal-only buildings as exemptions.
At a glance
Key figures: PV solar obligation in Valais
| Metric | Value |
|---|---|
| New building and extension | At least 20 W/m² of energy reference area; more than 30 kW cannot be required |
| Removing the roof covering | At least 20 W/m²; no more than 80% of the affected roof area |
| Roof area above 500 m² | On-site electricity generation within 25 years where irradiation exceeds 1,200 kWh/m² |
| Compliance measure for large roofs | At least 40% of the roof area or 20 W/m² of energy reference area |
| Economic exemption | At 25 centimes/kWh or less, disproportionality generally does not apply |
Decision points
What determines the right path.
The project trigger determines the rule: for new buildings and extensions, Art. 33 of the cantonal Energy Act requires at least 20 W/m² of energy reference area; more than 30 kW cannot be required. Under the cantonal page, an extension below 50 m² of energy reference area or below 20% of the existing area, but not exceeding 1,000 m², is exempt.
Removing the roof covering on an existing building triggers a separate obligation under Art. 43 of the cantonal Energy Act and Art. 64 of the Energy Ordinance. The target is at least 20 W/m² of energy reference area and no more than 30 kW; the module area need not exceed 80% of the roof surfaces whose covering is removed.
For roof areas above 500 m², installed capacity is not the only criterion. The building must generate its own electricity within 25 years of the cantonal Energy Act taking effect; only roof surfaces with average annual solar irradiation above 1,200 kWh/m² are mandatory. The requirement is met with at least 40% of the roof area or at least 20 W/m² of energy reference area.
Solar irradiation at the actual site limits the obligation. The Valais energy office points to map.geo.admin.ch for annual irradiation; for roof areas above 500 m², surfaces with average irradiation of no more than 1,200 kWh/m² do not have to be equipped.
An on-site system is not the only statutory compliance route. The Valais energy portal names equivalent production through financial participation in a renewable installation in the canton or a neighbouring canton, or through a self-consumption grouping. This alternative must be documented specifically in the project and proof planning.
An economic exemption is not an automatic waiver. According to the Valais energy page, the mandatory part will generally not qualify for a disproportionality exemption if generation costs are 25 centimes/kWh or lower; above that level, the case is assessed individually under Art. 5 of the Energy Act and Art. 5 of the Energy Ordinance.
Sequence
How the project stays cleanly managed.
- 1
Record the project triggerbefore requesting a quote, determine whether the project is a new building, an extension, removal of the roof covering or an existing building with more than 500 m² of roof area. These four cases use different reference values and periods in Valais under Arts. 33 and 43 of the Energy Act.
- 2
Measure the energy reference area and roof surfacesdocument the energy reference area for a new building or extension; for roof renovation, record the roof area actually stripped; above 500 m², separate the relevant partial surfaces as well. Without these areas, the 20 W/m² or 40% requirement cannot be determined reliably.
- 3
Check irradiation and exemptionsfor large roofs, compare average annual irradiation using map.geo.admin.ch. Then document GEAK class C after renovation, simultaneous facade renovation, north-facing roof renewal and seasonal-only use as possible exemptions.
- 4
Choose the compliance routesize the PV quantity under the 20 W/m², 30 kW, 80% or 500 m² rule, or assess an allowed alternative through financial participation or a self-consumption grouping. For an alternative, the location, participation and equivalence must be traceable in the energy proof.
- 5
Prepare EN-VS-104 and the economic assessmentthe Valais energy office provides the EN-VS-104 energy proof and implementation guidance. If economic disproportionality is claimed, document the generation costs of the mandatory part; 25 centimes/kWh or lower is generally not sufficient for an exemption.
- 6
Coordinate the building and energy proceduresthe selected system, alternative or exemption must match the building-application documents and energy proof. For the specific parcel, the municipality, the Energy Office and, for permit questions, the Cantonal Building Commission are decisive; a PV quote alone does not replace the proof.
Checklist
Questions to settle before the quote.
- New building or extension: 20 W/m² of energy reference area, 30 kW and possible alternatives
- Removing the roof covering: 20 W/m², no more than 80% of the affected roof area and exemptions
- Roof areas above 500 m²: 25-year period, 40% area rule and 1,200 kWh/m² irradiation
- EN-VS-104 energy proof, map.geo.admin.ch and economic disproportionality before requesting a quote
FAQ
More questions: PV solar obligation in Valais
Sources
Official sources & references.
The responsible authorities are decisive. Always verify binding details – amounts, deadlines and conditions – for your specific property against the current status of the respective authority.
- Photovoltaic solar energy and cantonal solar obligationsCanton of Valais, Energy Office
- Cantonal Energy Act, RS/VS 730.1Canton of Valais, official legislation collection
- Cantonal Energy Ordinance, RS/VS 730.100Canton of Valais, official legislation collection
- Cantonal guide to solar panels and permitsCanton of Valais, Cantonal Building Commission
- Federal Energy Act, Art. 45aSwiss Confederation, Fedlex