Short answerPayback period = (system cost − subsidy) ÷ yearly saving. For a 3 kW system costing ₹2,00,000 with a ₹78,000 subsidy and a ₹3,500 monthly bill (about ₹37,800 saved a year), payback is a little over three years, followed by more than two decades of savings.
Worked example
| System cost | ₹2,00,000 |
| Subsidy | − ₹78,000 |
| Net investment | ₹1,22,000 |
| Monthly bill covered (90% of ₹3,500) | ₹3,150 |
| Yearly saving | ₹37,800 |
| Simple payback | about 3.2 years |
What the calculator assumes
- Electricity tariffs rise 3% a year (a conservative figure).
- No financing cost. If you take a loan, see the EMI calculator.
- Your usage stays roughly the same.
How to shorten payback
- Size the system to your real yearly use, not your peak month.
- Shift heavy loads (washing machine, pumps, ironing) to daytime.
- Keep panels clean, especially in summer.
Frequently asked questions
What is a good payback period for rooftop solar?
For Telangana homes with the subsidy, four to five years is typical. Anything under seven years is a sound investment for a system that lasts 25 years.