PM Surya Ghar subsidy slabs built in
Solar Rooftop CalculatorSystem Size, Subsidy, Cost & Payback for Your Home
Find the right rooftop solar system for your home in under a minute. Enter your monthly electricity bill or units and this solar rooftop calculator works out the system size, number of panels and roof area you need. It then applies the PM Surya Ghar subsidy and shows your net cost, monthly savings, payback period and 25-year returns.
- ₹78,000 max central subsidy
- 25-year savings chart
- 3 tools in one
- No phone number or sign-up
1Your electricity use
2Location & system
Advanced assumptions
Cumulative savings over 25 years
Starts at your net cost and crosses zero at payback.
For residential grid-connected rooftop systems through the national portal and an empanelled vendor.
About 100 sq ft (10 sq m) per kW allows for panel spacing, walkways and tilt. Generation uses the units per kW per day from the first tab.
PM Surya Ghar subsidy for rooftop solar
Under PM Surya Ghar: Muft Bijli Yojana, homes with a grid-connected rooftop system get central financial assistance in slabs. The first 2 kW earn the highest rate, the third kW earns a lower rate, and the subsidy stops growing after 3 kW. Special category states, which include the North-East, hill states and island territories, receive 10% more.
| System size | General states | Special category states |
|---|---|---|
| 1 kW | ₹30,000 | ₹33,000 |
| 2 kW | ₹60,000 | ₹66,000 |
| 3 kW and above | ₹78,000 (maximum) | ₹85,800 (maximum) |
Several states add their own top-up on top of the central amount. Enter it in the State subsidy field to include it.
Solar system size by monthly units
In most of South and West India, 1 kW of rooftop solar produces roughly 4.2 units a day, or about 126 units a month. Use this table as a starting point, then use the calculator above for your exact bill.
| System | Units / month | 540 W panels | Roof area | Central subsidy |
|---|---|---|---|---|
| 1 kW | ~126 | 2 | ~100 sq ft | ₹30,000 |
| 2 kW | ~252 | 4 | ~200 sq ft | ₹60,000 |
| 3 kW | ~378 | 6 | ~300 sq ft | ₹78,000 |
| 4 kW | ~504 | 8 | ~400 sq ft | ₹78,000 |
| 5 kW | ~630 | 10 | ~500 sq ft | ₹78,000 |
| 10 kW | ~1,260 | 19 | ~1,000 sq ft | ₹78,000 |
Generation is typical, not guaranteed. It changes with location, season, shading, tilt and how often the panels are cleaned.
How the solar rooftop calculator works
Every number comes from a short, transparent formula. You can change any assumption, so the result reflects your home rather than a sales pitch.
Monthly units
units = bill ÷ tariff per unitSystem size
kW = units × cover % ÷ (daily yield × 30)Panels needed
panels = kW × 1,000 ÷ panel wattsCentral subsidy
₹30,000 × first 2 kW + ₹18,000 × 3rd kWMonthly savings
used units × tariff + surplus × export ratePayback
year when total savings ≥ net costAn honest solar panel calculator
Most solar calculators online belong to installers and ask for your phone number before showing a result. This one shows everything upfront and lets you test every assumption.
No lead form
No phone number, email or callback. Results appear instantly and stay on your device.
25-year savings chart
See exactly when the system pays for itself, with tariff rises and panel ageing built in.
Accurate subsidy slabs
Pro-rated central subsidy, the special category rate and your state top-up, all in one place.
Roof-aware sizing
Enter your shadow-free roof area and the calculator caps the system at what actually fits.
Region-based yield
Pick your region for typical sunshine, or type the yield your installer quoted.
Carbon impact
See how many tonnes of CO₂ your rooftop avoids each year compared with grid power.
How to use the solar rooftop calculator
Add your usage
Enter your average monthly bill or units. Average a few months, since summer and winter bills differ.
Pick your region
Choose your region for typical sunshine, then set the installed cost per kW from your quotes.
Check the roof
Add your shadow-free roof area so the recommended size is one you can actually install.
Read the payback
Review net cost, savings and the 25-year chart, then copy the summary to compare installer quotes.
Not sure how many units you use? Estimate appliance by appliance with the electricity cost calculator.
Benefits and buying tips
Size for usage, not subsidy
The subsidy stops at 3 kW, but your savings keep growing with every unit you replace.
Compare quotes per kW
Divide each quote by its kW so you compare like with like, including structure and wiring.
Use an empanelled vendor
The central subsidy is paid only for systems installed by vendors registered on the national portal.
Check the warranties
Look for a long panel performance warranty and a separate inverter warranty in writing.
Plan the financing
If you take a loan, check the EMI against your monthly savings with the EMI calculator.
Keep panels clean
Dust can noticeably cut output. Regular cleaning keeps generation close to the estimate.
Solar rooftop calculator FAQs
What size solar system do I need for my home?
Divide your monthly units by the monthly output of 1 kW, which is about 120 to 135 units in most of India. For example, a home using 380 units a month needs roughly a 3 kW system. The calculator does this for you and rounds up to the nearest half kilowatt.
How much subsidy can I get under PM Surya Ghar?
Homes get 30,000 rupees per kW for the first 2 kW and 18,000 rupees for the third kW, up to a maximum of 78,000 rupees for systems of 3 kW and above. Special category states receive 10% more, up to 85,800 rupees. Some states add their own top-up.
How much roof area is needed for 1 kW of solar?
Plan for about 100 square feet, or roughly 10 square meters, of shadow-free roof per kW. This allows space for panel spacing, tilt and maintenance access.
How many units does a 1 kW solar system generate?
A 1 kW rooftop system typically generates 3.6 to 4.6 units a day in India, depending on location, season, tilt and shading. That works out to around 110 to 140 units a month.
What is the payback period for rooftop solar?
With the central subsidy, many homes recover their cost in roughly 3 to 6 years. Payback is faster when your tariff is high and you use most of the solar power yourself.
Who is eligible for the rooftop solar subsidy?
Residential consumers with a grid-connected electricity connection can apply through the national PM Surya Ghar portal. The system must be installed by an empanelled vendor using eligible made-in-India panels. Commercial and industrial connections are not covered.
Is 3 kW the best solar system size?
3 kW collects the full central subsidy, so it often gives the best subsidy per rupee. However, if your usage is higher, a larger system still saves more money over time, so size it to your bill first.
How long do rooftop solar panels last?
Quality panels usually carry a 25-year performance warranty and lose a small share of output each year. The inverter typically needs replacing once during that period, so budget for it.
Turn your roof into savings
Your roof can pay for itself and keep cutting your bill for decades. Use this solar rooftop calculator to size the system, check your subsidy and see the payback before you talk to an installer.