Data Sources & Methodology

Last updated: 2026-07-07

Install Cost Data

• NREL — Tracking the Sun residential $/W benchmarks
• Regional labor and permit modifiers by state

Electricity Rates

• EIA average retail rates by state (¢/kWh)

Production Estimates

System output uses peak sun hours × system kW × 365 days × 0.85 performance derate, aligned with NREL PVWatts assumptions.

Incentives

30% federal ITC per current IRS residential guidance. State incentives vary — verify at DSIRE.

Limitations

Estimates are ranges, not quotes. Actual costs depend on roof, equipment, installer, and utility rules.