Estimate your ideal solar system size, installation cost, PM Surya Ghar subsidy, and payback period for your home — free and instant.
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If you're staring at a rising electricity bill and wondering whether rooftop solar makes sense for your home, this calculator gives you a realistic answer in under a minute — no sales call required. Punch in your average monthly bill and we'll estimate the system size you need, what it costs before and after the PM Surya Ghar Muft Bijli Yojana subsidy, and roughly how long it takes to pay for itself.
The numbers below use the same generation assumptions and subsidy slabs taught in IISE's solar energy training programs — so you're not just getting a marketing estimate, you're seeing the actual method professionals use to size a system.
We convert your average monthly electricity bill into units (kWh) consumed, using the tariff rate you enter. Most Indian households pay somewhere between ₹5.50 and ₹9 per unit depending on state and consumption slab — check your bill if you are not sure.
India's standard planning assumption is that 1 kW of rooftop solar generates about 4 units of electricity per day on average, accounting for sunlight hours, panel efficiency, and typical losses. This is the exact system sizing logic taught step-by-step in our installer training.
The central subsidy gives ₹30,000 per kW for the first 2 kW, and ₹18,000 for the third kW — capped at ₹78,000 for systems of 3 kW and above. Several states add their own top-up on top of this.
We compare your net investment (cost minus subsidy) against your estimated monthly savings to work out how many years it takes to break even — then project savings out to 25 years, the typical panel warranty period.
Enter your electricity bill to instantly estimate system size, cost, subsidy, and payback.
Estimates only, based on an average generation assumption of ~4 units/kW/day and current PM Surya Ghar subsidy slabs. Actual costs, generation, and eligibility vary by location, shading, roof orientation, and DISCOM. This is not the official government calculator — apply directly on the PM Surya Ghar portal for exact subsidy confirmation.
The central government's PM Surya Ghar Muft Bijli Yojana subsidises residential rooftop solar in slabs, up to a maximum of ₹78,000. Systems of 3 kW and above receive the full cap — which is also why most installers recommend sizing to at least 3 kW where the roof allows it.
| System Size | Central Subsidy | Approx. Cost (before subsidy) | Approx. Net Cost |
|---|---|---|---|
| 1 kW | ₹30,000 | ₹65,000 – 75,000 | ₹35,000 – 45,000 |
| 2 kW | ₹60,000 | ₹1.10 – 1.30 Lakh | ₹50,000 – 70,000 |
| 3 kW Most Popular | ₹78,000 (max) | ₹1.80 – 2.00 Lakh | ₹1.02 – 1.22 Lakh |
Homes needing more than 3 kW typically add the extra capacity without further central subsidy, since the residential cap stops at ₹78,000. Housing societies and group installations fall under a separate RWA subsidy track with different slabs.
Here's a realistic worked example for a household with a ₹2,500/month electricity bill at a ₹7/unit tariff, with enough roof space to fit the recommended system:
Assuming steady tariffs and no major panel degradation, that same system could offset roughly ₹6.4 Lakh in electricity costs over 25 years — after the payback period, essentially all further savings are pure upside. Real-world results will vary with tariff changes, panel performance, and how efficiently the system was installed, which is exactly why proper design and installation quality matters as much as sizing.
As a rule of thumb, plan for about 100 sq ft of shadow-free roof area per kW of installed capacity, using standard 540–550W panels.
| System Size | Approx. Roof Area Needed | Approx. Panels (550W each) |
|---|---|---|
| 1 kW | ~100 sq ft | 2 panels |
| 2 kW | ~200 sq ft | 4 panels |
| 3 kW | ~300 sq ft | 6 panels |
| 5 kW | ~500 sq ft | 10 panels |
Shading from water tanks, parapets, or neighbouring buildings reduces usable area and generation — a proper site survey accounts for this in a way no online calculator can. Orientation matters too: south-facing roofs typically generate the most in India.
Rooftop solar is one of the fastest-growing employment segments in India's renewable energy sector. If sizing and calculating systems like this interests you, here's where to go next:
From beginner diplomas to PG-level programs — browse IISE's full solar training catalogue.
Read More →Understand how battery storage and micro-grids extend a rooftop system's value after sunset.
Read More →See how a home solar system can also offset electric vehicle charging costs.
Read More →1-month hands-on program covering rooftop sizing, wiring & installation. July 2026 batch.
Browse IISE's full solar energy training catalogue — from beginner diplomas to PG programs.
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