Cantonal information · Last updated September 2026
Solar panels in Valais: PV obligations for new buildings and roof renovations in 2026
Valais energy legislation has applied since 1 January 2025. It requires on-site power not only for new buildings and certain extensions: removing the roof covering from an existing building can also trigger a solar obligation.
Large roofs of more than 500 m² are additionally subject to a long-term installation obligation. The project type, energy reference area, roof area being worked on and any exceptions must therefore be examined separately.
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Valais roof-renovation check
When the roof covering is removed, an existing building must generally produce some of the electricity or heat it consumes. For PV, the ordinance specifies at least 20 W/m² of energy reference area, capped at 30 kW.
Is your roof being opened?
Work through these steps in order.
- Roof covering removed?
1. Establish the scope
For a minor repair, clarify the specific scope separately; if the roof covering is removed, check the obligation.
Sources: 1 - Four exceptions
2. Check the exceptions
Possible exceptions are an overall GEAK/CECB class C after renovation, simultaneous energy renovation of all façades, work only on the north side, or exclusively summer use.
Sources: 1 - 20 W/m² ERA
3. Calculate capacity
Without an exception, allow for at least 20 W per m² of energy reference area, but no more than 30 kW.
Sources: 2 - max. 80%
4. Limit the roof area
The required PV area need not occupy more than 80% of the newly covered roof area.
Sources: 2
The required installation area may occupy no more than 80% of the roof surfaces from which the covering is removed. Minor repairs that do not remove the roof covering must therefore be classified differently from actual reroofing.
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New buildings and extensions: 20 W/m², no more than 30 kW
New buildings and covered extensions must achieve at least 20 W of renewable on-site power capacity per m² of energy reference area, or ERA. This obligation never requires more than 30 kW.
An extension is exempt if its new ERA is less than 50 m². It is also exempt if it amounts to less than 20% of the existing ERA and is no larger than 1,000 m². A specific statutory exception applies to Minergie buildings already equipped with PV.
Subject to the statutory conditions, the corresponding production can also be provided through a financial stake in a renewable installation in Valais or a neighbouring canton, or through a collective self-consumption arrangement.
Roofs over 500 m²: a separate 25-year rule
Buildings with more than 500 m² of roof area must be equipped to generate electricity within 25 years of the Act entering into force. This covers surfaces with average annual irradiation above 1,200 kWh/m².
Assessment route for a large roof
This obligation is separate from the roof-renovation rule.
- >1,200 kWh/m²/year
2. Solar potential
Roof surfaces above the specified average annual irradiation are relevant.
Sources: 1 - 25 years
3. Deadline
The equipment must be installed within 25 years of the 1 January 2025 commencement date.
Sources: 1 - 40% of roof or 20 W/m² ERA
4. Compliance
Either option satisfies the area or capacity requirement; connection capacity remains the upper limit.
Sources: 2
The required capacity is limited by the existing electrical connection capacity. The requirement is met either with PV on at least 40% of the roof area or with at least 20 W/m² of energy reference area.
Handle notification and funding separately
If a solar installation is exempt from the standard building permit procedure, it must be notified to the competent authority 30 days before work begins. Installations on cultural monuments or natural sites of cantonal or national importance still require a permit.
For ordinary photovoltaics, the canton refers applicants to Pronovo. The Valais Buildings Programme supports other renovation and heating measures and is not a flat-rate cantonal PV payment. Municipal assistance must be checked separately; no general cantonal bonus for ordinary home batteries is confirmed.
For existing buildings, eligible investment costs can be deducted from taxable income under cantonal tax guidelines. The canton provides special tax treatment for proceeds up to 10,000 kWh. Check the current guideline through the official solar-energy link; it does not establish any guaranteed tax saving.
Solar project in Valais
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Frequently asked questions
- Does every minor roof repair in Valais trigger a solar obligation?
- No. A key point is whether the roof covering is removed. Sources: 1
- What requirement applies to a covered roof renovation?
- At least 20 W/m² ERA, capped at 30 kW; the PV area is limited to 80% of the newly covered area. Sources: 2
- Which exception may apply after a roof renovation?
- Examples include an overall GEAK/CECB class C, simultaneous energy renovation of all façades, work only on the north side, or exclusively summer use. Sources: 1
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Sources and last update
Last updated: 21 September 2026
- Canton of ValaisEnergy Act of 8 September 2023Official source
- Canton of ValaisEnergy OrdinanceOfficial source
- Canton of Valais, Energy and Hydropower ServiceSolar energy: obligations, procedures and fundingOfficial source
- Canton of ValaisSolar installations exempt from permits and notification procedureOfficial source
- Canton of ValaisTax treatment of photovoltaic installationsOfficial source
- Pronovo Ltd on behalf of the Swiss ConfederationOne-off payment for photovoltaic installationsOfficial source