Turn a sales proposal into an offer you can actually compare. Use the same assumptions for every offer and verify the latest terms directly.
Specify the complete installation
Request the panel count and model, system capacity, inverter model and any battery. Ask whether scaffolding, roof work, cabling, electrical-board changes and monitoring are included. Require optional items to be priced separately.
Ask for the assumptions
A savings calculation should state annual generation, self-consumption, export rate, import rate and any assumed price growth. Ask what happens under a lower-generation or lower-export-payment scenario. A forecast that depends on optimistic price rises may be fragile.
Review warranties and aftercare
Check the different warranties for equipment and workmanship. Ask who you contact if the system stops reporting or underperforms. Understand any service charges and whether remote monitoring requires a subscription.
Clarify payment and delivery
Get the payment schedule, target dates and cancellation terms in writing. Ask what happens if the roof survey changes the scope. Compare the gross price and any proposed grant treatment separately so every quote uses the same basis.
Use a short comparison sheet
Create columns for supplier, capacity, included works, battery, gross price, grant assumption, net price, warranty and aftercare. Leave unknowns visible and ask for them to be filled in. A complete smaller quote is easier to judge than a low headline with undefined extras.
Sources & review notes
This guide explains our comparison approach and calculation methods. Numerical examples are illustrative and do not represent supplier offers.
Reviewed 9 October 2026. Prices, grant conditions and provider terms can change. Check the relevant provider or official body before acting.
Our editorial and comparison approachPut the guide into practice.
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