1. Identify contractors and their qualifications
Request the legal company name, comparable project references and subcontractors. Specify who assesses the roof, installs equipment, performs electrical work and arranges inspections. Check authorisation for the electrical tasks concerned. Swissolar distinguishes its member search from the directory of Solarprofis-labelled companies; membership alone does not mean certification under that label.
2. Provide a consistent comparison brief
Provide the address, roof condition, consumption, future uses and required functions. Request the layout, exact models, capacity and monthly generation with assumptions. Distinguish a different technical option from an omitted service. Equal panel counts are insufficient; another capacity may suit the need if costs and results are explained.
3. Itemise prices and procedures
Compare equipment, mounting, scaffolding, electrical work, access, connection, tests and documents. Separate options, VAT, exclusions and possible charges. Define responsibilities, authorisation to act, documents and timing for each application or grant. Pronovo procedures vary by project; do not assume every application precedes work or that only the installer can apply.
4. Distinguish forecasts, warranties and insurance
Request product, power and installation warranty terms, exclusions and claim costs. A kWh forecast is not a contractual generation guarantee. Check insurance certificates, insured activities and responsibilities without assuming every error will be reimbursed. Specify labour, roof access, transport, replacement and the fault-reporting contact.
5. Arrange payment and handover
Read payment milestones, associated work, variations, delays and termination terms before signing. Define tests and handover criteria. Keep plans, models, serial numbers, electrical records, monitoring access and warranties. Separate delivery, installation, inspections and permission to commission in the schedule; a sales date alone does not confirm every stage.
6. Check the service actually available
Ask who monitors alerts, contact hours, agreed response times and travel charges. Check parts, equipment replacement and data access if providers change. A nearby contractor may make visits easier; its address guarantees neither availability nor speed. Compare written service terms and relevant references instead of a general ranking.