Path-Q Solar

What information should I request when an installer gives only an annual production figure?

Answer

Request the assumptions and a time-based production breakdown behind the annual figure before using it to compare quotes. At minimum, obtain the system layout, equipment, orientation, tilt, shading losses, weather data, degradation assumption, and monthly production estimate.

Key points

  • Ask for production by month and, where useful, by roof section or system component.
  • Request the modeled losses for shading, soiling, temperature, wiring, availability, and other factors included by the installer.
  • Confirm whether the figure is an estimate, a warranty, or a contractual commitment.

What it depends on

  • Roof orientation, tilt, usable area, and shading
  • Equipment specifications and system size
  • Weather dataset, modeling software, and loss assumptions

Risks and trade-offs

  • Two annual figures can look similar while having different seasonal production and modeling risk.
  • A high estimate based on optimistic assumptions may overstate savings.
  • Actual production varies with weather, equipment condition, shading changes, and downtime.

Information you may need

  • Monthly production report
  • Array layout and equipment list
  • All loss, degradation, shading, and weather assumptions

Your next step

What to do next

Ask the installer for a complete production report and use the same requested fields to normalize every quote before comparing them.

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SQ02033