Payback Period Calculator
Work out how long solar panels, a machine or any other investment takes to pay for itself from what it saves or earns each year.
Maintenance, cleaning or servicing. Optional.
Optional: shows the total gain over its life.
Payback period
3 years and 9 months
- Net saving a year
- Rs 240,000
- Gain over 15 years
- Rs 2,700,000
It pays for itself in 3 years and 9 months, and over 15 years comes out Rs 2,700,000 ahead.
How it's worked out
- Payback
Rs 900,000 ÷ Rs 240,000 a year3.75 years
Year by year
| Year | Net saving | Still to recover | |
|---|---|---|---|
| Year 1 | Rs 240,000 | Rs 660,000 | |
| Year 2 | Rs 240,000 | Rs 420,000 | |
| Year 3 | Rs 240,000 | Rs 180,000 | |
| Year 4 | Rs 240,000 | Rs 0 | Paid back |
| Year 5 | Rs 240,000 | Rs 0 | |
| Year 6 | Rs 240,000 | Rs 0 | |
| Year 7 | Rs 240,000 | Rs 0 | |
| Year 8 | Rs 240,000 | Rs 0 | |
| Year 9 | Rs 240,000 | Rs 0 | |
| Year 10 | Rs 240,000 | Rs 0 | |
| Year 11 | Rs 240,000 | Rs 0 | |
| Year 12 | Rs 240,000 | Rs 0 | |
| Year 13 | Rs 240,000 | Rs 0 | |
| Year 14 | Rs 240,000 | Rs 0 | |
| Year 15 | Rs 240,000 | Rs 0 |
- This is simple payback: it doesn't allow for prices or savings changing over time. A shorter payback means less risk if things change.
How it is worked out
With the same saving each year, payback = upfront cost ÷ (yearly saving − running costs). With different savings, the calculator subtracts each year's net saving from the cost until nothing is left, and works out the fraction of the final year.
Questions people ask
How long does a 900,000 system saving 240,000 a year take to pay back?
3.75 years, or 3 years and 9 months. Over 15 years it comes out 2,700,000 ahead.
What if the savings change from year to year?
Choose Different each year and list them. The calculator adds up each year's saving until the cost is covered, counting part of the last year.
Should I include running costs?
Yes: maintenance, cleaning and servicing reduce the yearly saving, so they lengthen the payback.
Is a shorter payback always better?
It means less risk, but it ignores what happens after payback. Compare the gain over the whole life too.
About this calculator
Formula and rules last checked 10 November 2026Written and tested by the CalculatorDex teamReport a problem