Solar Payback Calculator

This calculator estimates solar savings over the system's lifetime. Year-one production is based on system size × annual production per kW, adjusted for roof direction. Each subsequent year accounts for panel degradation (typically 0.5%/year) and rising electricity rates. The payback period is when cumulative savings exceed the net system cost (after tax credits). For loan financing, monthly payments are calculated using standard amortization. CO₂ offset uses the EPA average of 1.22 lbs CO₂ per kWh avoided. The 30% federal Investment Tax Credit (ITC) under the Inflation Reduction Act is applied by default.