THE SHORT ANSWER
Treat a production number as an estimate unless the signed agreement clearly creates a guarantee and defines measurement, exclusions, remedy and term.
Find every production number
List annual kWh figures in the proposal, design report, sales presentation, financing documents and contract. Mark differences and version dates. NREL describes PVWatts as a calculator for energy estimates. [1] A modeled value does not become a guarantee because it appears in large type.
Read the controlling language
FTC solar guidance recommends reviewing agreements and getting promises in writing. [2] Search for estimate, forecast, guarantee, remedy, exclusions and dispute terms. Ask which signed document controls when marketing material and contract language do not match.
Define measurement if a guarantee exists
A meaningful provision should say what meter or monitoring record is used, the evaluation period, weather or availability adjustments, owner responsibilities, notice procedure and remedy. Do not invent these terms or assume a manufacturer warranty covers total system energy.
Separate energy from bill savings
Even a defined energy obligation would not necessarily guarantee a utility bill. Household consumption, tariffs, fixed charges, export compensation and financing are separate variables. Ask the proposal to label production, consumption, bill-offset and payment statements distinctly.
Keep the signed evidence
Save the final contract, incorporated exhibits, model report and any written clarification together. Verbal statements and later screenshots may be hard to reconcile. If the provision matters to the decision, obtain qualified legal or financial advice rather than relying on a sales interpretation.
Before your next conversation
- List all production figures.
- Identify the controlling signed document.
- Read measurement and remedy terms.
- Separate energy from utility-bill claims.
Primary sources
- Federal Trade Commission: Solar Power for Your Home
Primary source reviewed September 10, 2026. Utility rules, equipment availability, project design and contract terms remain specific to the property and proposal.
- National Renewable Energy Laboratory: PVWatts Calculator
Primary source reviewed September 10, 2026. Utility rules, equipment availability, project design and contract terms remain specific to the property and proposal.
Planning examples and questions are Origin’s editorial guidance, not a property-specific diagnosis, engineering design, tax determination or promise of savings. Manufacturer and utility references do not imply an affiliation with Origin.
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