Solar Payback
Calculator
Results
- Net cost after incentives
- 12,600
- Annual savings
- 1,530
- Payback period (years)
- 8.235294
- Net savings over 25 years
- 25,650
Energy results
| Net cost after incentives | 12,600 |
| Annual savings | 1,530 |
| Payback period (years) | 8.235294 |
| Net savings over 25 years | 25,650 |
formula-map diagram
- Net cost after incentives
- 12,600
- Annual savings
- 1,530
- Payback period (years)
- 8.235294
- Net savings over 25 years
- 25,650
Energy relationship
Formula
Payback = (cost − incentives) ÷ (annual kWh × price)= 12600
Note
This is a simplified model: it applies the standard equation to the numbers you entered and ignores real-world losses, weather variation, tariff structures and equipment tolerances. Wind power assumes air density 1.225 kg/m³ at ISA sea level and the power coefficient you enter (Betz limit 0.593). Verify with measured data or a professional energy audit before making purchasing decisions.
More in Energy and environment
See all →Frequently asked questions
What exactly does the payback period measure?+
It's the number of years it takes for cumulative electricity savings to equal your net system cost after any incentives or rebates. After that point, the system is generating savings rather than recovering its own cost.
Does the calculation include rising utility rates?+
A basic version assumes a flat annual savings amount, but a more accurate model applies an annual rate escalation, since electricity prices have historically risen a few percent per year. Ignoring escalation understates savings and overstates the payback period.
How do tax credits and rebates factor in?+
Incentives reduce your net upfront cost before the payback calculation runs, so a 30% federal tax credit, for instance, directly shortens the payback period by lowering the amount that needs to be recovered through savings.
Why do two similar systems have very different payback periods?+
Payback is highly sensitive to your local electricity rate, the system's production (driven by sun hours and orientation), and the installed cost per watt, so even similar-sized systems in different regions or with different financing can vary by several years.
Does payback period tell the whole financial story?+
No, it ignores what happens after the breakeven point, when a system with a 25-30 year lifespan keeps generating savings for another one to two decades. Comparing total lifetime savings or return on investment gives a fuller picture than payback period alone.