Background
#The solar obligation for new builds in St. Gallen means in the standard case: under Art. 5b EnG SG, new buildings must generate part of their electricity themselves, and Art. 4c EnV SG specifies at least 10 W per m² of energy reference area.
The obligation is not a general recommendation but a building- and energy-law project requirement that must be translated into roof area, structural load and electrical planning before the building application. One important boundary is the 30 kW cap per building; more does not have to be installed for the self-generation obligation, even if the roof allows more capacity.
Exemptions particularly concern extensions to existing buildings if the newly created energy reference area is below 50 m² or no more than 20 percent of the existing energy reference area and no more than 1,000 m². The workflow involves the building authority, the Office for Water and Energy of Canton St. Gallen and the local grid operator, not only the solar contractor.
What roof and planning dictate
#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.
The process in seven steps
#Tick off for your project
Trigger building type and obligation
before 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.
Calculate minimum capacity
multiply 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.
Check roof area and structure
translate 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.
Link building application and energy proof
present 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.
Prepare the grid connection
identify 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.
Plan incentives and commissioning
the 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.
Document deviations
if 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.
Checked for your roof, not just read up on
Once the framing is clear, a property-specific check with roof, grid and documentation is worthwhile.
Frequently asked questions
#Sources
#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.