Path-Q Solar

What should I do if a quote does not show how roof shading was modeled?

Answer

Do not compare the quote as if its production estimate were fully verified. Ask the installer to disclose the shading method, data source, time horizon, affected roof areas, and resulting production losses, and request a revised estimate if the method is unclear or unsupported.

Key points

  • Ask for a roof layout showing obstructions and the parts of the array affected by shade.
  • Request monthly or interval production assumptions rather than only an annual total when shading materially varies by season.
  • Compare the shading assumptions with another installer or an independent site assessment if the difference could affect the decision.

What it depends on

  • Nearby trees, buildings, roof features, and their future growth
  • The accuracy and resolution of the modeling data
  • Array layout, module placement, and use of any module-level optimization

Risks and trade-offs

  • Understated shade losses can make savings and payback appear better than they are.
  • Overly conservative modeling can make a viable design appear unattractive.
  • Tree growth and future construction can change shading after installation.

Information you may need

  • Shading model or report
  • Obstruction heights, locations, and assumed future growth
  • Monthly production estimates before and after shading losses

Your next step

What to do next

Send the installer a written request for the shading assumptions and a revised production report, then compare the response with another quote using the same site facts.

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