Solar Rooftop Calculator
From your electricity bill to the right solar system, its cost after subsidy, and when it pays for itself.
At a glance
- Sizes a rooftop system from your monthly bill or units, using typical sunshine for your state, and checks it fits your roof.
- Works out the PM Surya Ghar central subsidy for homes: ₹30,000 per kW for the first 2 kW and ₹18,000 for the 3rd — up to ₹78,000 (10% more in special-category states).
- Shows the monthly saving, the payback period and 25-year savings, counting panel ageing, rising tariffs and surplus units sold back under net metering.
- Compares the monthly saving with a loan EMI, so you can see whether solar pays its own instalments.
- Every assumption — cost per kW, units per kW, export price, tariff rise — is shown and can be changed.
- A year-by-year chart and table of money saved, and the CO₂ your panels avoid.
Step by step
How to calculate rooftop solar for your home
- 1
Choose your state
It sets how many units each kW of panels produces where you live.
- 2
Enter your bill
Your average monthly bill (or units) and the price per unit.
- 3
Add your roof area
Optional — the shade-free area where panels can go.
- 4
Read the result
The recommended size, cost after subsidy, monthly saving and payback. Adjust the assumptions to match a vendor’s quote.
Features
Everything you need, nothing you don’t
Right size
From your bill, your state’s sunshine and your roof.
Subsidy built in
PM Surya Ghar slabs, with special-category states.
Real payback
Panel ageing, tariff rises and net metering included.
Loan check
EMI against your monthly saving.
Your numbers
Change any assumption to match your quote.
25-year view
Chart and table of savings, year by year.
PM Surya Ghar subsidy for homes
*North-eastern states including Sikkim, Himachal Pradesh, Uttarakhand, Jammu and Kashmir, Ladakh, Andaman and Nicobar, and Lakshadweep. The subsidy is for residential connections, installed by a registered vendor and applied for on the national portal (pmsuryaghar.gov.in). Some states add their own subsidy on top.
| System size | Central subsidy | Special-category states* |
|---|---|---|
| 1 kW | ₹30,000 | ₹33,000 |
| 2 kW | ₹60,000 | ₹66,000 |
| 3 kW or more | ₹78,000 | ₹85,800 |
How much does a home solar system produce?
In most of India, 1 kW of panels produces about 3.5 to 4.5 units a day — roughly 110 to 140 units a month — more in Rajasthan, Gujarat and Ladakh, less in the cloudy north-east. So a home using 300 units a month needs about 2.5 kW, which takes around 250 sq ft of shade-free roof. Panels lose about 0.5% of their output each year and usually come with a 25-year performance warranty.
FAQ
Frequently asked questions
What size solar system do I need?
How much does a 3 kW solar system cost after subsidy?
How long does rooftop solar take to pay back?
What happens to the units I don’t use?
Is the subsidy available for shops or offices?
Does it include batteries?
Keep going
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