Your break-even is a number you can plan around.
Solar Savings & Payback Calculator
Enter your system size, sun hours, electricity rate, and installed cost to see yearly production, annual savings, and exactly when the panels pay for themselves.
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Solar savings & payback
Live - local onlyYour savings report appears here
Set your system details on the left, then press Calculate savings. You'll get the payback period and a year-by-year breakdown.
This is an estimate for planning, not a quote. Real production varies ±20% with roof orientation and shading. Everything runs locally in your browser.
A practical answer, before the long explanation.
Size the system
Enter capacity in kW and the daily sun hours for your location from your roof's exposure.
Add the economics
Your electricity rate, installed cost, degradation, price inflation, and inverter replacement.
See the break-even
Year-by-year savings, the payback period, and total profit across the system lifetime.
What this estimate assumes
Production applies a performance ratio of 80% to nameplate capacity to account for shading, inverter losses, soiling, and temperature. Real output varies ±20% with roof orientation, tilt, and local weather.
Savings assume your utility lets you net-meter all the electricity you generate, and that electricity prices rise at the inflation rate you enter. Export tariffs, tax credits, maintenance, and financing costs are not included, and panel output declines each year by the degradation rate you enter.
The result is an estimate for planning, not professional financial or energy advice. Your actual payback depends on installer pricing, incentives in your state, and how your utility bills solar customers.
The formula
Yearly production (kWh) = size (kW) × sun hours/day × 365 × 0.8 performance ratio
Yearly savings ($) = production (kWh) × rate ($/kWh) × (1 + inflation)² × (1 − degradation)²
The payback period is the year cumulative savings first cover the installed cost plus any inverter replacement in year 10. Worked example: a 5 kW system in 4.5 sun hours at $0.16/kWh costing $13,700 pays for itself in about 12 years and 3 months.