Path-Q Solar

How can I identify production assumptions that are missing from a solar proposal?

Answer

Ask the installer to disclose the inputs behind the production estimate, including site orientation, tilt, shading, weather data, equipment losses, degradation, availability, system size, clipping, curtailment, and future load or export assumptions. Compare the estimate with an independent model or measured site information.

Key points

  • Annual production alone does not show how output varies by month or hour.
  • Loss assumptions should explain shading, temperature, wiring, mismatch, inverter efficiency, soiling, snow where relevant, and downtime.
  • The proposal should distinguish modeled production from guaranteed production.
  • Export limits, battery dispatch, and utility rules can reduce usable or compensated output.

What it depends on

  • Site survey and shading analysis
  • Equipment specifications and layout
  • Weather dataset and modeling method
  • Tariff, export, battery, and curtailment assumptions

Risks and trade-offs

  • Optimistic assumptions can overstate savings and payback.
  • A production guarantee may exclude factors that materially affect actual output.
  • Independent modeling may identify uncertainty but is not a guarantee of future generation.

Information you may need

  • Hourly or monthly production model
  • Loss table and degradation assumption
  • Shading report and layout
  • Export, battery, and utility operating assumptions

Your next step

What to do next

Request the complete production model and have a qualified independent reviewer compare its assumptions with the site and proposed equipment.

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SQ01949