Path-Q Solar

What questions should I ask before agreeing to let an installer use estimated roof measurements?

Answer

Ask how the measurements were obtained, what uncertainty they carry, and whether the price and design can change after an on-site verification. Estimated measurements may support an initial proposal, but they should not be treated as final when roof geometry, condition, setbacks, or structural details affect the project.

Key points

  • Ask whether measurements came from imagery, plans, or a physical survey.
  • Request the proposed roof planes, panel layout, shading assumptions, setbacks, and obstructions.
  • Confirm which items remain subject to site verification, structural review, permitting, or utility approval.
  • Require the contract to state how measurement errors affect system size, price, schedule, and cancellation rights.

What it depends on

  • Complexity of the roof and number of roof planes
  • Accuracy and age of available imagery or plans
  • Roof condition and structural information
  • Installer's change-order and cancellation terms

Risks and trade-offs

  • Incorrect measurements can reduce production, create layout changes, or increase cost.
  • A later site visit may reveal roof repairs, electrical work, access issues, or structural limitations.
  • A low initial quote may depend on assumptions that are not included in the final contract.

Information you may need

  • Measurement source and date
  • Preliminary layout and production estimate
  • List of assumptions and excluded work
  • Site-verification procedure and contract change terms

Your next step

What to do next

Ask the installer to provide the assumptions in writing and schedule an on-site survey before signing an irreversible agreement or approving final design.

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SQ00440