5 Questions to Ask Before Buying Solar

1. How did you size the system?

Ask for the consumption data, roof survey and production assumptions used. A monthly bill in euros does not uniquely determine annual kWh or the right system size, because tariffs and fixed charges differ.

The proposal should explain orientation, shade, usable roof area, inverter sizing and any export limits. Ask how generation coincides with your demand and how seasonal occupancy affects the forecast. A generic sunshine count is not a site-specific yield model.

• Request separate estimates for generation, direct self-consumption, export and import.
• Ask to see a lower-generation scenario as well as the central forecast.
• Do not accept a roof layout that ignores access, structure or shading.

2. What exactly are you supplying?

Request manufacturer and exact model numbers for panels, inverter, mounting, protection, monitoring and any battery. Compare datasheets and compatibility for those models, not an unspecified product family.

Distinguish product warranty, output-performance conditions and workmanship obligations. The current Spain-applicable terms should explain exclusions, registration and the route for a claim. No panel nationality or brand label guarantees better support.

• Confirm whether substitutions require your written approval.
• Identify roof penetrations, waterproofing and structural responsibilities.
• Check battery backup separately from ordinary grid-connected operation.

3. Who handles permissions and registration?

Ask which municipal and regional procedures apply to your particular installation and who prepares, submits and follows up each document. Requirements may depend on property type, heritage status, collective ownership and system configuration.

A claim that paperwork is included should list the deliverables and any fees. Distinguish physical completion from authorisation, registration and supplier activation of export compensation. Obtain evidence of submissions and final documents.

• Confirm any community-of-owners agreement needed before works.
• Identify the distributor and supplier roles rather than treating them as one company.
• Do not assume a grant application means an award has been approved.

4. What does the financial forecast leave out?

Compare the full installed cost including tax, access equipment, electrical upgrades and optional items. Forecast savings using the actual import tariff, export terms and demand profile, with standing charges retained.

Ask for maintenance, financing, degradation and replacement assumptions. Keep unapproved grants and tax relief outside the base case. A simple-payback figure is not an investment guarantee or evidence of a property-value increase.

• Compare every quote on the same annual consumption and tariff assumptions.
• Check cancellation, deposit and staged-payment terms.
• Ask how a lower future electricity price affects the calculation.

5. Who is accountable after installation?

Identify the contracting legal entity, any subcontractors, applicable credentials and insurance. Ask for current documents instead of treating a website badge as proof.

Agree commissioning tests, system access, user training, monitoring alerts and the process for reporting defects. Request consented references for comparable work and distinguish measured results from sales forecasts. LIT is the primary specialist for the installation discussion; Energy Centre provides this buyer's checklist.