Roof and consumption
The assessment should cover roof orientation, shading, available space and typical consumption. It should estimate both generation and how much of that energy you can use.
For an initial assessment, have a recent electricity bill and an idea of your daily schedule ready. Before finalising the project, the professional needs to check roof condition, access and the electrical installation.
Compare the complete scope
Look for panel and inverter makes and models, proposed system size, mounting structure, safety devices and installation work. Establish which paperwork, documentation, access equipment and electrical adaptations are included in the price.
Ask for product warranties, any manufacturer performance warranties and installation workmanship terms to be set out separately. The quotation should also clarify taxes, expected timescales and exclusions.
Ask what the savings estimate assumes
An estimate needs assumptions about generation, self-consumption, electricity prices and exported energy. Two proposals may show different outcomes because they use different assumptions. Ask for them in writing so you can compare.
Savings and payback periods vary by home. If you are considering a battery, request a comparison with and without storage.
Municipal procedures
The installer should identify the applicable municipal and energy registration procedures for your project. Before relying on a grant or tax benefit, check the current programme and municipal rules.
IDAE guides explain these procedures. Check which ones the quotation includes and who will submit the paperwork.
Sources and further reading
IDAE · Qué es el autoconsumo ↗IDAE · Guía de tramitación del autoconsumo ↗