CalcVind

Solar Panel Calculator

Rooftop solar size, cost after subsidy, savings and payback

Your Electricity Use

From your electricity bill

units (kWh)
₹per unit

About 4 in most of India; 4.5–5 in Rajasthan and Gujarat

units

On-grid home systems: about ₹55,000–85,000 per kW

₹
₹

Estimates. Ask a registered vendor for a site survey and exact quote.

A 2.5 kW System Suits You

2.5 kWSystem size
₹93,500Cost after subsidy
3.2 yearsPayback
₹1,62,500
Cost before subsidy
₹69,000
PM Surya Ghar subsidy
₹2,400
Saving per month
300 units
Generation per month
about 250 sq ft
Roof area needed
  • You pay₹93,500(58%)
  • Subsidy₹69,000(42%)
Read the guide · 6 minPM Surya Ghar Solar Subsidy: How Much You Get and How to ApplyRead the guide · 5 minHow Long Will My Inverter Battery Last? Backup Time Explained
  1. 1
    Enter your monthly units
    From your electricity bill
  2. 2
    Check rate and cost
    Defaults suit most of India
  3. 3
    See size and payback
    After the PM Surya Ghar subsidy

How is solar system size worked out?

In most of India, 1 kW of rooftop solar produces about 4 units a day, or 120 a month. Divide your monthly use by that, then round up to the next half kilowatt.

System size (kW) = monthly units ÷ (units per kW per day × 30)

Subsidy = ₹30,000/kW for 2 kW + ₹18,000 for the 3rd kW (max ₹78,000)

PM Surya Ghar subsidy

Under PM Surya Ghar: Muft Bijli Yojana, homes get a central subsidy of ₹30,000 for 1 kW, ₹60,000 for 2 kW and ₹78,000 for 3 kW or more, paid to your bank account after the DISCOM commissions the system. Apply at pmsuryaghar.gov.in and use a registered vendor. Some states add their own subsidy.

Net metering

On-grid systems export unused daytime power to the grid and draw it back at night; the net meter records both. This calculator assumes solar covers up to your monthly use. Extra generation is usually credited at a lower rate.

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Frequently asked questions

How much solar do I need for 300 units a month?

About 2.5 kW: 300 ÷ (4 × 30) = 2.5 kW, producing roughly 300 units a month.

What does a 3 kW system cost after subsidy?

At about ₹65,000 per kW, roughly ₹1.95 lakh before subsidy and ₹1.17 lakh after the ₹78,000 central subsidy, plus any state subsidy.

How long do solar panels last?

Panels usually carry a 25-year performance warranty and lose about 0.5% output a year. Inverters typically need replacing once in that time.

Sources

Last reviewed: October 2026