Rooftop Solar Savings Calculator
Estimate payback, lifetime savings and CO₂ avoided for a rooftop solar system in India.
Result
- Recommended system size
- 4.7kW
- Net upfront cost
- ₹1,79,813
- Payback period
- 3.2years
- First-year savings
- ₹54,750
- 25-year net savings
- ₹16,62,006
- CO₂ avoided over 25 years
- 121.5tonnes
Estimates only. Nothing you type is stored or sent anywhere — the calculation runs entirely in your browser.
How this works
Rooftop solar in India pays for itself through avoided grid electricity, not through export income. The single biggest driver of your payback period is your per-unit tariff — the higher your slab rate, the faster the system pays back. A household in a ₹9/kWh slab typically breaks even years earlier than one in a ₹5/kWh slab, even with identical hardware.
This calculator sizes the system from your monthly consumption assuming roughly 4 peak sun hours per day, which is a conservative national average. Rajasthan and Gujarat run higher; the Northeast and coastal Kerala run lower. It then applies your capital cost per kW, the subsidy you expect to receive, and a modest annual tariff escalation, because grid tariffs have historically risen faster than inflation.
Degradation is modelled at 0.6% per year, which is typical for tier-1 crystalline silicon panels under warranty. The 25-year figure assumes one inverter replacement is already priced into your per-kW cost. If it is not, subtract roughly 8–10% of the system cost from the lifetime savings.
Common questions
- How much rooftop area do I need per kW?
- Budget roughly 80–100 square feet of unshaded roof per kW for standard panels. A 5 kW system therefore needs around 400–500 square feet with clear southern exposure.
- Does the PM Surya Ghar subsidy change the answer?
- Yes, substantially. Central financial assistance for residential rooftop systems materially cuts the upfront cost and can shorten payback by more than a year. Enter the subsidy amount you actually expect to be sanctioned rather than the headline maximum.
- What happens to the extra units I generate?
- Under net metering your surplus units are credited against future consumption, usually within the same billing year. Under net billing or gross metering you are paid an export rate that is lower than the retail tariff, which lengthens payback.