How to choose a solar installer
Before signing, identify the contractors responsible for the roof, electrical work, grid connection and Pronovo. Compare required permits, references and the written scope of the quotation.
A clear quotation assigns each task to a responsible party. A company's age or a professional logo alone does not prove competence. Review projects comparable to yours and ask for site and after-sales contacts.
Permits and evidence to check
Electrical work: check which contractor holds the ESTI permit under the Low-Voltage Electrical Installations Ordinance and which work it covers. Membership of suissetec or another professional association does not replace this permit. Also ask who provides the safety certificate and inspection documents.
Pronovo concerns the installation and one-off grant application, rather than a commercial installer certification. Specify who prepares the application, holds access, provides documents and manages deadlines. For a small installation under the small-system grant scheme, the application is submitted after completion; other schemes have their own procedures.
Swissolar provides a Solarprofi directory. Verify the claimed status in the official directory and references relevant to the project. Membership or a label guarantees neither a specific yield nor freedom from defects. For any other certification, ask for the issuer, criteria, scope and validity.
Installation quality: request datasheets, the electrical diagram, sizing evidence, planned inspections and an acceptance report. Specify waterproofing, fixings, protection and documents provided at the end of the work.
7 questions before signing
1. Who performs the electrical work, and under which permit?
Confirm the permit holder, scope and responsibility in the quotation.
2. Which comparable projects have you completed?
Check experience, roof configuration and references, rather than years in business alone.
3. Can I review recent references?
Request documented examples and customers you can contact with their consent.
4. Who works on the roof: your team or subcontractors?
Identify each contractor, its role, insurance and responsible contact.
5. Which warranties and rights apply to installation?
Check who handles fixing or waterproofing defects and intervention costs.
6. Who prepares the Pronovo application, and when?
The timetable depends on the scheme; the small-system grant application follows completion.
7. How do you assess a difference between simulated and actual production?
Ask for weather assumptions, monitoring, tolerances and the diagnostic process.
Points to examine in a quotation
Validity and sales pressure: a very short deadline needs an explanation. A quick response is not a fault, but artificial urgency should not replace a site visit, roof assessment or time to compare quotations.
Expected production: request a simulation stating orientation, tilt, shading, weather, losses and data sources. A high figure without documented assumptions is not evidence of quality. Also compare a cautious scenario and the actual value of self-consumed and exported electricity.
Service: specify monitoring, subscriptions, diagnostics, travel, parts and response times. A maintenance contract is not automatically essential for every installation. Any promised deadline must appear in the quotation with conditions and exclusions; there is no general guarantee of intervention within 72 hours.
Price and warranties: separate panels, inverter, mounting, cables, installation, scaffolding, administrative work and connection. Distinguish product warranty, performance warranty, contractor commitments and rights relating to defects. Panel warranty duration depends on the model and manufacturer.