Solar panel payback calculator
Change anything and the result updates instantly. The electricity price defaults to your state's latest EIA average; replace it and the installed cost with the numbers from your bill and your quote.
First-year savings
$1,580
Payback
12.5 years
25-year net gain
$27,028
Return (IRR)
6.9%
Production vs. use by month
9,950 kWh/yr produced · covers 40% of your use directly · 42% of output used on the spot.
Which size pays off best?
Same usage and prices, only size changes. Best 25-year net gain: 8 kW.
| kW | Cost | Year-1 savings | Payback | 25-yr gain |
|---|---|---|---|---|
| 3 | $9,000 | $677 | 13.5 years | $10,155 |
| 4 | $12,000 | $903 | 13.1 years | $14,373 |
| 5 | $15,000 | $1,129 | 12.8 years | $18,591 |
| 6 | $18,000 | $1,354 | 12.6 years | $22,810 |
| 7 | $21,000 | $1,580 | 12.5 years | $27,028 |
| 8 | $24,000 | $1,667 | 13.0 years | $29,936 |
| 10 | $30,000 | $1,667 | 15.7 years | $24,455 |
| 12 | $36,000 | $1,667 | 18.2 years | $18,455 |
Estimate based on NLR PVWatts and EIA data. See the methodology.
How to read the result
- First-year savings: what you stop paying for power you use directly, plus bill credits for power you export.
- Payback: years until cumulative savings (minus maintenance) equal the installed cost minus incentives.
- kWh that earn no credit: exports beyond a year of grid purchases. Most utilities zero out or pay very little for excess credits at the annual true-up, so oversizing rarely pays.
The model, data sources and limits are explained in the methodology. Find your state's numbers on the state pages.