Short answer
What you need to know first.
In Canton St. Gallen, new buildings must generate their own electricity under Art. 5b EnG SG or reduce energy demand by 5 kWh per m² per year. Art. 4c EnV SG sets the PV-related obligation at at least 10 W per m² energy reference area, capped at 30 kW per building.
Important
As of 2026, the key boundary is this: the St. Gallen solar obligation is a minimum requirement for new buildings under EnG/EnV SG, but not a guarantee that every roof area is technically, legally or economically optimal for full coverage. Protected buildings, grid connection, fire safety, roof structure and property-specific building-permit conditions must be checked separately.
Decision points
What determines the right path.
The first factor is the energy reference area: Art. 4c EnV SG requires at least 10 W of self-generation per m² of energy reference area. A new build with 180 m² ERA therefore lands at a calculated minimum capacity of 1.8 kW; the canton cites a substitute levy of just over CHF 4,800 for a single-family house of this size if no self-generation is chosen.
The second factor is the 30 kW cap: Art. 4c para. 1 EnV SG states that 30 kW per building need not be exceeded. For larger roofs, this separates the legal minimum obligation from economically sensible full coverage, which is additionally checked through self-consumption, feed-in and grid connection.
The third factor is extensions: Art. 4d EnV SG exempts extensions to existing buildings if the new energy reference area is below 50 m² or no more than 20 percent of the existing ERA and no more than 1,000 m². This exemption belongs in the building application, not only in the quote phase.
The fourth factor is the alternative under Art. 5b EnG SG: anyone who does not generate self-produced electricity may reduce the weighted energy demand for heating, hot water, ventilation and cooling by 5 kWh per m² of heated area per year. This option is an overall energy design choice, not a late opt-out from PV.
The fifth factor is the self-consumption association: Art. 4c para. 3 EnV SG allows proof across several buildings if there is a long-term ZEV agreement under Art. 17 of the federal Energy Act, the buildings are part of the same special-use plan and they are approved in the same building-permit procedure.
The sixth factor is technical implementation before construction starts: the Energy Ordinance has applied since 1 July 2021, but the grid connection runs through the local distribution grid operator such as St.Gallisch-Appenzellische Kraftwerke AG or the St. Gallen municipal utility. Building application, roof structure, inverter capacity and connection request therefore have to be planned together.
Sequence
How the project stays cleanly managed.
- 1
Trigger building type and obligationbefore the building application, clarify whether the project is a new build or an extension and whether Art. 5b EnG SG applies at all. For extensions, document the new energy reference area in m², because Art. 4d EnV SG sets concrete exemption limits at 50 m², 20 percent and 1,000 m².
- 2
Calculate minimum capacitymultiply the energy reference area by 10 W per m² and apply the 30 kW cap per building. This number is the energy-law minimum; the actually planned PV capacity may be higher for economic reasons.
- 3
Check roof area and structuretranslate minimum capacity into module area, layout, roof load and inverter capacity. For flat roofs, tilt racking, edge distances, wind loads and maintenance paths belong in this step before the PV system appears in the building application as a feasible measure.
- 4
Link building application and energy proofpresent the chosen solution consistently in the energy proof and the building application. If reducing energy demand by 5 kWh per m² per year is chosen instead of self-generation, that variant must be demonstrated by calculation.
- 5
Prepare the grid connectionidentify the responsible distribution grid operator at the site and prepare the connection request, metering concept and installation notice. In Canton St. Gallen, SAK, the St. Gallen municipal utility or another local grid operator may be responsible depending on the municipality.
- 6
Plan incentives and commissioningthe self-generation obligation does not replace the Pronovo check. The one-time remuneration is handled separately through Pronovo; after installation come the safety certificate, grid release, meter process and complete system documentation.
- 7
Document deviationsif an exemption, substitute levy or ZEV proof across several buildings is used, the legal basis, calculation and responsibility should be recorded in writing. Especially for special-use plans, Art. 4c para. 3 EnV SG requires a long-term regulated ZEV agreement.
Checklist
Questions to settle before the quote.
- Check whether Art. 5b EnG SG applies to the new build or extension
- Calculate minimum capacity from energy reference area and classify the 30 kW cap
- Document exemptions for extensions below 50 m² or 20 percent of the energy reference area
- Manage the PV obligation, roof planning, building permit and grid connection in one schedule
FAQ
Common questions on this topic.
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.