Compare the proposed layout first
The quotation should identify where the panels will be installed, their orientation and any roof sections affected by shade. A larger panel count is not automatically better if some of the array sits on weak roof areas.
Expected annual production should be tied to that layout. Ask which losses have been allowed for and whether the estimate reflects the actual orientations rather than an ideal south-facing roof.
Make sure the equipment is identifiable
Panel, inverter and battery models should be named clearly enough to check their specifications and warranties. A brand name without the model can cover equipment with different capacities or features.
The quotation should also cover mounting, monitoring, electrical protection and any switching required for backup. If storage is optional, its cost and role are easier to judge when shown separately.
Look carefully at exclusions
Scaffolding, lifting equipment, difficult cable routes and remedial electrical work can change the final price. The proposal should say whether these are included, excluded or subject to a site check.
Roof repairs and upgrades to an older consumer unit should not be hidden inside a vague allowance. If their extent cannot yet be confirmed, the uncertainty should be stated.
Registration and legalisation are part of the installation
A completed solar system needs the appropriate technical documentation, commissioning and registration. The exact route depends on the installation and property, so the quotation should identify who handles it and what the price includes.
Where surplus compensation is planned, the owner may also need documentation for the electricity supplier. Supplier account changes and tariff arrangements are separate from physically installing the array.
Read warranties as separate promises
A panel product warranty, performance warranty, inverter warranty and installer workmanship warranty do not cover the same things. Check their duration, who provides them and what happens if equipment needs attention.
Monitoring and aftercare also need a named route. Owners should know who receives system alerts, whether remote diagnosis is available and how a warranty visit is arranged.
Compare what the system is expected to do
A credible proposal explains how much electricity is expected to be generated, how much may be used directly and what a battery would change. Savings depend on occupancy, tariffs and behaviour, so unusually precise promises deserve scrutiny.
The clearest comparison separates facts, estimates and optional equipment. That makes it easier to see whether a lower price represents a more efficient design or simply a shorter scope of work.
Questions homeowners ask
Should legalisation be included in a solar quotation?
The quotation should state clearly whether technical documentation, registration and legalisation are included and who is responsible for completing them.
Can I compare quotations by price per panel?
That misses roof layout, inverter design, mounting, electrical work, monitoring and legalisation. Compare the complete proposed system and its expected production.
Are equipment and installation warranties the same?
No. Product, performance and workmanship warranties cover different parts of the project and may be provided by different organisations.