Solar Panel ROI Calculator
Estimate your solar payback period, 25-year savings, and return on investment
How to Use This Calculator
- Enter your planned system size in kilowatts (kW). A typical home system is 5–10 kW.
- Input your local peak sun hours/day — use the U.S. average of ~4.5 if unsure, or look up your region.
- Add your electricity rate in $/kWh (check your utility bill; the U.S. average is about $0.16).
- Enter the installed cost per watt and your incentive percentage (the federal Residential Clean Energy Credit is 30%).
- Optionally adjust the annual electricity rate escalation (default 3%).
- Read your payback period, annual production, and 25-year savings instantly.
Solar ROI Formula
Annual Production = System Size (kW) × Peak Sun Hours × 365
Annual Savings = Annual Production × Electricity Rate
Net Cost = System Size × 1000 × Cost/Watt × (1 − Incentive)
Payback (years) = Net Cost ÷ Year-1 Annual Savings
25-Year Savings = Sum of escalating annual savings (with 0.5%/yr panel degradation) − Net Cost
| System Size | Annual Production* | Year-1 Savings ($0.16/kWh) | Est. Payback (30% ITC, $2.80/W) |
|---|---|---|---|
| 4 kW | 6,570 kWh | $1,051 | ~7.5 yrs |
| 6 kW | 9,855 kWh | $1,577 | ~7.5 yrs |
| 8 kW | 13,140 kWh | $2,102 | ~7.5 yrs |
| 10 kW | 16,425 kWh | $2,628 | ~7.5 yrs |
| 15 kW | 24,638 kWh | $3,942 | ~7.5 yrs |
*Based on 4.5 peak sun hours/day. Actual results vary by location, shading, and equipment.
Solar Panels & Equipment for Your ROI
Frequently Asked Questions
What is a good solar payback period?
Most U.S. residential systems pay back in 6–10 years. Under 8 years is considered excellent; the calculator above shows your estimate based on local rates and incentives.
Does the calculator include the 30% federal tax credit?
Yes — set the Incentive field to 30% (the default) to apply the Residential Clean Energy Credit to your net cost.
Why does my payback differ from the table?
Payback depends on your local electricity rate, peak sun hours, installed cost, and incentives. The table uses national averages of $0.16/kWh, 4.5 sun hours, $2.80/W, and 30% ITC.