Short answer
What you need to know first.
Guidance for owners in Basel-Stadt who want to clarify before PV planning whether their installation only requires notification to the BGI or needs a formal building permit, and what the revised 2025 Solar Offensive, protection zones and heritage protection specifically mean for their project.
Important
This page provides general guidance based on the official BGI information on the building permit procedure for solar installations (bs.ch/bvd/bgi) and the revised Solar Offensive of the Basel-Stadt cantonal government (2025). Whether a specific installation is subject to notification or requires a building permit depends on the zoning category, building status and technical execution parameters. The binding assessment is made by the BGI. For buildings with heritage protection or protection zone status, pre-consultation with Basel-Stadt heritage authority is expressly recommended before any quote or installation planning is prepared.
Decision points
What determines the right path.
Notification or building permit, the zoning category decides first: in the number zone, zone of public interest, conservation zone and for inventoried objects and in the industrial and commercial zone (Zone 7), a notification to the BGI is sufficient for adapted installations. As soon as the building is in a protection zone or under heritage protection, a formal building permit is required.
The technical conditions for the notification procedure are clearly defined: the installation must not protrude more than 20 cm perpendicular to the roof surface, must not extend beyond the roof surface when viewed from the front or from above, must be low-reflection, and must form a compact, contiguous area. If even one of these conditions is not met, a notification is no longer sufficient and a building permit becomes necessary.
Historic town centres newly accessible: the revised 2025 Solar Offensive has lifted the previous ban on PV installations in the historic town centres of Basel, Riehen and Bettingen. Projects in these previously restricted areas are now fundamentally possible. However, in sensitive areas within the town centres, a building permit remains required, and the heritage authority decides on a case-by-case basis for inventoried buildings about location and execution.
Heritage protection as an independent review hurdle: buildings classified as cultural monuments of cantonal or national significance are exempt from the new solar obligation. For inventoried buildings and buildings in the protection zone, Basel-Stadt heritage authority decides on a case-by-case basis whether and on which roof surfaces a PV installation can be approved. This heritage assessment is an independent step before the formal permit procedure and should be obtained as early as possible.
Facade installations in zones 4, 5, 5a and 6 have their own thresholds: compact facade installations in these zones are subject to notification if they are at least 100 m² in size, generate at least 12 kWp, and are well integrated into the facade. Smaller or poorly integrated facade installations require a building permit. This threshold is particularly relevant in the dense building stock of Basel-Stadt for apartment buildings with street facades.
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.
Sequence
How the project stays cleanly managed.
- 1
Determine zone and building statusfirst check which zoning category the building falls under, number zone, conservation zone, protection zone, industrial and commercial zone or another zone, and whether it is listed in the cantonal or municipal heritage inventory. This first step determines whether a notification to the BGI suffices or whether the heritage authority needs to be involved early.
- 2
Check installation against notification criteriaif the zone generally allows the notification procedure, verify the technical conditions: maximum perpendicular projection of 20 cm above the roof surface, no visibility beyond the roof edge from the front or above, low-reflection execution and compact module layout. Only if all conditions are met does the project remain in the notification procedure.
- 3
For heritage protection or protection zoneinitiate pre-consultation with heritage authority and BGI: as soon as a building is inventoried or located in a protection zone, the Basel-Stadt heritage authority should be contacted early, before the quote, not just when the application is filed. This pre-consultation prevents planning documents from being prepared that would need to be substantially revised during formal review.
- 4
Submit notification or building application to the BGIthe 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.
- 5
Coordinate IWB grid registration in parallelat 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.
- 6
Consider the solar obligation in project planningowners of a building with more than 100 m² of suitable roof area who do not yet operate a PV installation should include the 15-year transition period of the Solar Offensive in their planning. Non-compliance triggers a substitute levy of CHF 150 per kilowatt payable in ten annual instalments. Cultural monuments of cantonal or national significance are exempt from this obligation.
Checklist
Questions to settle before the quote.
- Notification in practice: which zones and technical conditions determine notification or permit in Basel-Stadt
- Historic town centres and heritage protection: what the 2025 Solar Offensive specifically changes for PV projects in sensitive areas
- Solar obligation and transition period: which buildings with more than 100 m² of roof area are affected and which exceptions apply
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.