# Why is the payback period on my Easy PV project different from an identical design produced on a different software?

There is a variety of reasons the payback period could have come out differently. Even with identical kit and system cost, many different assumptions made throughout a design can lead to significant differences in the payback period.

The first things to check are:

- [**Performance task**](https://help.easy-pv.co.uk/link/113#bkmrk-performance-results--1): Is the generation figure the same? If not, are the proposals using the same shading factors?
- **[Consumption](https://help.easy-pv.co.uk/link/93#bkmrk-below-that-will-be-t)/[Financial task](https://help.easy-pv.co.uk/link/75#bkmrk-financial-task-input)**: Is the total consumption the same? Are the tariffs the same? Is the self-consumption calculation method the same?
- [**Financial task**](https://help.easy-pv.co.uk/link/75#bkmrk-financial-task-input): Is the inflation, degradation and discount rate the same?

The most common reason for significant differences in payback time is that most other software calculates a standard payback period, whereas we use a *discounted* payback period. In short, a discount rate helps reflect the fact that £100 now is worth more than £100 earned in 10 years. Translating future earnings into terms of today's money has a negative impact on the total income and savings values and leads to a higher, but more accurate figure. The discount rate can be adjusted down to 0 in the [financial settings](https://help.easy-pv.co.uk/link/75#bkmrk-financial-settings-s) of a project to make Easy PV also calculate a standard payback period.

**<span class="corp-icon material-symbols-rounded icon-readmore mceNonEditable" style="user-select: none;">​</span>Learn more**: [Consumption task](https://help.easy-pv.co.uk/books/performance-and-consumption/page/getting-started-with-the-consumption-task "Getting started with the Consumption task"), [Financial task](https://help.easy-pv.co.uk/books/financial-task/page/using-the-financial-task "Using the Financial task"), [Performance task](https://help.easy-pv.co.uk/books/performance-and-consumption/page/performance-task "Performance task").