What is Rooftop Solar ROI Calculator?
Rooftop Solar ROI Calculator helps you compare rooftop solar installation costs with projected annual net savings.
The main result is simple annual return, with a breakdown of annual generation and annual net savings. The formula, example and assumptions below explain how to interpret it.
How to use Rooftop Solar ROI Calculator
Use the example to get familiar with the form, then enter your own figures. Any rates in the example are illustrative. Check the field labels and units before calculating.
- Gather solar system size (kW), average daily peak sun hours (hours), system performance ratio (%), value per generated kWh (₹), net installed cost after subsidy (₹) and annual maintenance costs (₹). Use values from the same situation or reporting period.
- Replace the example solar system size with your own value, then complete the other fields. Check the displayed units.
- Select Calculate and read simple annual return with its result breakdown. Change one input and calculate again to compare a second scenario. Reset restores the original example.
- Enter solar system size in kW, at least 0. Decimals are accepted.
- Enter average daily peak sun hours in hours, at least 0.001 and at most 24. Decimals are accepted.
- Enter system performance ratio in %, at least 0 and at most 100. Decimals are accepted.
- Enter value per generated kWh in ₹, at least 0. Decimals are accepted.
- Enter net installed cost after subsidy in ₹, at least 0. Decimals are accepted.
- Enter annual maintenance costs in ₹, at least 0. Decimals are accepted.
Rooftop Solar ROI Calculator: a worked example
With the inputs below, the result is 22.16 % (simple annual return). Follow the example, then replace these illustrative values with your own.
| Input or output | Example value |
|---|---|
| Solar system size (kW) | 5 kW |
| Average daily peak sun hours (hours) | 5 hours |
| System performance ratio (%) | 80 % |
| Value per generated kWh (₹) | ₹8 |
| Net installed cost after subsidy (₹) | ₹2,50,000 |
| Annual maintenance costs (₹) | ₹3,000 |
| Simple annual return | 22.16 % |
| Annual generation | 7,300 kWh |
| Annual net savings | ₹55,400 |
Understanding the Rooftop Solar ROI result
Read simple annual return alongside annual generation and annual net savings. These describe different parts of the same calculation.
Displayed results use a readable number of decimal places. When checking a result by hand, keep extra precision until the last step. To compare scenarios, change one input at a time and keep the others fixed.
- Example Annual generation: 7,300 kWh
- Example Annual net savings: ₹55,400
Rooftop Solar ROI Calculator: assumptions and common mistakes
A useful estimate starts with the right inputs. Check the following assumptions and limits before applying the result to your situation.
- Assumes all generated energy has the entered value. Degradation, finance, tariff changes and export/self-use differences are not modelled.
- Match factors to your location and reporting period. A result covers the sources you entered, not an independently verified full footprint.
For wider guidance, visit GHG Protocol calculation guidance. The formula and scope of this specific tool are stated on this page.
