Background
#In Basel-Stadt, a solar installation requires either notification or a building permit. According to the Building and Trade Inspectorate (BGI), notification depends in part on the zone and technical criteria; a permit is required in a protection zone or for a listed building.
The 2025 Solar Offensive proposes an obligation to use suitable roofs on existing buildings and changes for historic town centres. However, as of 20 July 2026, the canton still describes it as a revised proposal referred to the Grand Council; parliamentary file 25.0921 is marked “In progress”. Treat those planned rules as proposals, not as obligations currently in force.
Before requesting a quote, owners should check zoning and protection status, apply the current BGI criteria and plan grid registration with IWB separately.
For your roof
What fits on your roof?
Enter your address to see roof area, yield and a guide price from federal data. We then clarify notification or permit with your municipality.
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What applies in the canton of Basel-Stadt
#The current BGI route depends on both zone and system. The BGI lists rooftop systems in the number zone, agricultural zone, zone for public-interest uses and conservation zone as subject to notification if the technical criteria are met. A building permit is required in a protection zone or for a listed building. An inventory entry should not be treated as a blanket notification exemption; owners should confirm the specific status with the BGI and heritage authority.
Pitched roofs, flat roofs and facades have different criteria. For pitched roofs, these include a maximum 20 cm projection perpendicular to the roof, no extension beyond the roof when viewed from above, low reflectivity and a compact layout; the BGI allows technically necessary gaps or an offset layout where space requires it. Flat roofs also have a maximum 1 m above the roof edge and a 45-degree visibility test from below. Facades must meet the basic criteria and at least one of the design criteria listed by the BGI; the BGI determines the procedure for the specific project.
The Solar Offensive is not yet the legal basis for the procedure. The 2025 proposal includes changes for historic town centres, but on 20 July 2026 the canton still listed referral to the Grand Council as the current status; parliamentary file 25.0921 is marked “In progress”. Until any changes enter into force, the current BGI rules on zoning, protection status and system design apply. For a specific building, do not assume either a blanket ban has been lifted or that the installation is generally permitted.
Check protection status before planning. The BGI requires a building permit for systems in a protection zone or on a listed building. Where a property appears in an inventory, owners should ask the heritage authority before detailed design which protection category applies and which elevations or documents are needed. Exemptions from the proposed solar obligation do not determine today’s permit route.
The current BGI page does not list a 100 m² or 12 kWp minimum for facades. It requires that the system not cover architectural details, extend beyond facade edges, sit more than 20 cm from the facade or depart from uniform, low-reflection materials. At least one BGI design criterion must also apply, such as a compact rectangular area, uniform replacement of facade elements, complete gable coverage, matching colour or location in a work zone.
IWB grid registration runs in parallel, not via the BGI: in Basel-Stadt, IWB is the sole grid operator. Grid registration, including the grid connection application, metering concept and technical approvals, is an independent process and does not run automatically through the building permit procedure. Anyone who coordinates grid registration and building procedure only late in the process risks delays at commissioning.
The process in six steps
#Tick off for your project
Determine zoning and protection status first
check the current zoning and whether the building is listed or lies in a protection zone. The BGI names the number zone, agricultural zone, zone for public-interest uses and conservation zone as possible notification areas for eligible rooftop systems. For inventory entries, ask the BGI and heritage authority to identify the specific protection category before planning.
Check criteria by system type
pitched roofs include a maximum 20 cm projection perpendicular to the roof, no extension beyond the roof when viewed from above, low reflectivity and compact layout. Flat roofs add the 1 m roof-edge limit and 45-degree visibility test. Facades have separate basic and individual criteria. Prepare the roof plan, elevations and sections so the applicable rule can be checked from the drawings.
Resolve protection questions early
a building permit is required in a protection zone or for a listed building. For inventoried properties, ask the BGI and heritage authority to confirm which protection rules apply. Obtain this classification before detailed design so the module plan, elevations and section reflect the actual requirements.
Submit notification or building application to the BGI
the notification for notification-required installations can be submitted via the BGI's eFormular (Bau- und Gastgewerbeinspektorat, Münsterplatz 11, 4001 Basel, bvdbgi@bs.ch). For permit-required installations, the formal building application must be submitted with the necessary plans, elevations and descriptions.
Coordinate IWB grid registration in parallel
at the same time as the building law procedure, prepare grid registration with IWB (Industrielle Werke Basel), grid connection application, metering concept and technical approvals. These processes should be timed so that commissioning is not delayed by waiting times at either body.
Track the Solar Offensive as a proposal
the 2025 proposal includes an obligation for suitable existing roofs, a 15-year transition period and a substitute levy of CHF 150 per kW in ten annual instalments. On 20 July 2026 the canton still listed the proposal as referred to the Grand Council, where the file remains in progress. Do not treat these figures as law unless an amendment is adopted and enters into force.
Checked for your roof, not just read up on
What fits on your roof?
Enter your address to see roof area, yield and a guide price from federal data. We then clarify notification or permit with your municipality.
Free and non-binding · no unsolicited calls
Rather talk directly? +41 78 615 90 58
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.