Path-Q Solar

What evidence should an installer provide for claims about future electricity savings?

Answer

The installer should provide a transparent calculation linking your historical or expected electricity use, modeled solar production, bill rules, equipment costs, financing, and operating assumptions to the claimed savings. Savings should be presented as estimates with assumptions and sensitivity ranges, not as guaranteed results unless a written guarantee specifies its terms.

Key points

  • Request the production model, shading basis, system losses, degradation assumption, and expected annual output.
  • Ask for the rate, fixed-charge, export-credit, and escalation assumptions used in the bill model.
  • Separate gross bill reduction from financing payments, maintenance, replacement, and other costs.
  • Request conservative, expected, and downside cases.

What it depends on

  • The site's solar resource and shading
  • Actual and future electricity consumption
  • Current and future bill rules, rates, and financing terms

Risks and trade-offs

  • Savings can be overstated by using high rate escalation or favorable export assumptions.
  • A production estimate is not the same as a bill-savings guarantee.
  • Financing and equipment replacement costs can materially change net savings.

Information you may need

  • The complete savings worksheet or model
  • The data source for production and consumption estimates
  • All pricing, financing, maintenance, and replacement assumptions

Your next step

What to do next

Ask the installer to rerun the savings model with conservative assumptions and independently check the rate and export inputs before signing.

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SQ01480