Start with the same home information
Provide each installer with the same electricity-use records, roof information and photographs you can safely take from ground level. Mention the roof age if known and identify shade or access concerns as observations. Separate verified information from estimates. A proposal based on a different roof area or consumption period is not directly comparable. Ask which site checks remain outstanding and whether the design is preliminary. This helps explain why proposals may describe different system sizes.
Compare the complete equipment scope
Ask for the proposed panels, inverter arrangement, mounting approach and monitoring equipment to be identified. Clarify what installation and connection work is included and what is excluded. Discuss any assumed roof work or electrical changes with the installer rather than treating them as already settled. If a battery is optional, compare the solar-only and battery scopes separately. Keep product information with the proposal so later discussions refer to the same equipment configuration.
Ask how estimates were developed
Request the assumptions behind generation or savings estimates, including the roof layout, shade inputs and electricity-use period. Ask how uncertainty is described and which inputs could change after assessment. Do not treat an illustration or estimate as a household result or a guarantee. If a proposal depends on a programme or incentive, ask the installer to identify the current official criteria and what eligibility remains unverified. This guide does not calculate savings or confirm programme eligibility.
Check responsibilities and handover
Ask who coordinates the project-specific permissions and connection steps, which documents you will receive and what remains your responsibility. Confirm the warranty providers and terms for equipment and installation separately. Discuss monitoring access, fault reporting and after-installation support. Request a written explanation of outstanding conditions before accepting a proposal. An enquiry through this site records project interest. Arrange assessments, installations and written terms independently with an installer you choose.