A clear contract protects as much as the choice of panels. Check the site data and official sources before signing.
Decision to make
A clear contract protects as much as the choice of panels. Adapt this decision to the building, your actual consumption and the project schedule.
For this project, start by identifying the grid operator, applicable tariff and site constraints. The quotation must specify the conditions affecting connection, metering or the value of surplus electricity.
Practical effects of the project
- Confidence is verified in the parts: electrical authorizations, local references, exact brands, guarantees and calendar.
- A very low price must be explained line by line: material, subcontracting, scaffolding, procedures and connection.
- The contract must limit the deposit, set milestones, specify commissioning and provide for the procedure to follow in the event of delay.
- The seller must explain the sources for the tariff, estimated production, grants and local constraints.
- After-sales service is a purchasing criterion: monitoring, response time and responsibility after connection.
These points help assess the topic ‘ Solar contract: deposit, deadline, guarantee and clauses to be locked ’ without turning a national average into a local promise. Every decisive figure needs its source, date and scope.
Specific controls
- Confirm site data with the relevant professionals and connection conditions with the grid operator.
- Show base price, options, connection, aid and exclusions separately.
- Compare a reference hypothesis with a conservative variant before signing.
The answers should appear in the quote or in a dated appendix. A verbal explanation is insufficient if it changes the price, expected output, financial support or a contractual obligation.
Compare quotes
- Tariffs: state the purchase price, surplus remuneration and fixed charges applicable to the site, with their source and date.
- Production: provide a monthly estimate with orientation, shading, losses and weather assumptions.
- Investment: separate material, installation, safety, scaffolding, connection, procedures and options.
- Aids: distinguish confirmed amount, estimate and deposit liability.
- Contract: specify guarantees, calendar, deposit, exclusions, maintenance and after-sales service.
A clear contract protects as much as the choice of panels. In the comparison table, keep one column for the stated value, one for the evidence provided, and one for the effect of a less favorable hypothesis.
Cautious scenario
Test the project with slightly lower production, an unconfirmed grant and less favourable surplus remuneration. This scenario shows whether the decision remains sound based on self-consumption, roof quality and a controlled installed cost.
The main references used are Pronovo - Submit a photovoltaic subsidy application, SFOE - permits and low-voltage installations, Confederation - Sonnendach / solar potential of roofs, ElCom - Slight drop in electricity prices in 2026. They frame the method, but the local amounts and contractual conditions must be rechecked at the time the offer is signed.
Risks to be managed
After-sales service is a purchasing criterion: monitoring, response time and responsibility after connection. Ask who assumes this risk, what proof will be provided and how a change is handled after ordering.
A more expensive solution should meet a specific need in your project. Ask for a documented benefit and a separate price for each option.
Next step
Gather the address, annual consumption, future electricity uses and building documents. Then check the grid operator's conditions, available grants and site constraints; request quotations covering the same scope.
A clear contract protects as much as the choice of panels. You can then decide with a documented net price, clear responsibilities and assumptions that each company can explain line by line.
Points to check
- Tariffs: Compare the tariff for your address with the Swiss ElCom median for 2026, keeping local prices separate from the national benchmark.
- Grants: Check the programme, eligibility, documents and deadlines with Pronovo, the canton or municipality. Include only confirmed contributions in your budget.
- Roof potential: Sonnendach is presented as a public pre-diagnosis, to be validated by a technical visit.
- ROI: the method separates self-consumption, injection, installed price, taxation and payment schedule.
- Confidence is verified in the parts: electrical authorizations, local references, exact brands, guarantees and calendar.
- A very low price must be explained line by line: material, subcontracting, scaffolding, procedures and connection.