Free Solar Calculator for Rooftop Solar in India
Calculate the solar system size you may need based on your electricity usage, roof area, and location. Get an estimated system capacity, panels, generation, cost, savings, subsidy, and payback in minutes.
Where is your property located?
Regional solar insolation directly determines daily electricity generation.
Electricity Consumption vs. Solar Generation
Your Solar Investment Breakdown
25-Year Cumulative Savings & Payback Projection
Factoring 0.7% annual solar panel degradation and 3% annual grid tariff escalation.
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Get your roof layout, sanctioned load, and PM Surya Ghar subsidy reviewed by an experienced IISE solar engineering consultant.
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What is a Solar Calculator?
A solar calculator is a techno-commercial simulation tool designed to estimate the optimal capacity, energy yield, capital expenditure, and payback period of a rooftop photovoltaic (PV) system for your property.
Who Should Use It?
Homeowners seeking ₹0 power bills under PM Surya Ghar, factory managers reducing LT/HT costs, and installers validating project sizing.
Why Location Matters
Solar insolation across India varies between 4.3 to 5.5 peak sun hours per day depending on regional latitude, cloud cover, and seasonal monsoons.
Why Roof Space Matters
High-efficiency 550W modules measure ~2.27 m². Accounting for inter-row tilt pitch and walkway access, ~85 sq. ft. is required per 1 kW.
Why Tariffs Matter
Avoided grid costs drive returns. DISCOM tiered slab rates (₹6 to ₹12/unit) determine your monthly rupee savings and payback speed.
How to Use the Free Solar Calculator
What Does the Solar Calculator Calculate?
| Calculated Metric | Unit | Engineering Description & Formula |
|---|---|---|
| Solar Capacity | kW (Kilowatts) | Recommended DC PV capacity sized from daily units and regional peak sun hours at 75% Performance Ratio. |
| Solar Panels | Module Count | Total number of high-efficiency 550 Wp Tier-1 Mono PERC modules required (Capacity ÷ 0.55 kW). |
| Annual Generation | kWh (Units/Yr) | Total expected clean AC electrical energy generated over a full 365-day annual meteorological cycle (~1,400 to 1,550 kWh/kW/yr). |
| Roof Area Required | sq. ft. | Shadow-free rooftop space required including inter-row tilt pitch and maintenance walkways (~85 sq. ft. per kW). |
| Estimated Capex | ₹ (INR) | Turnkey capital cost including panels, string inverter, mounting structure, BOS cabling, and net metering. |
| PM Surya Ghar Subsidy | ₹ (INR) | Direct benefit transfer: ₹30,000 (1 kW), ₹60,000 (2 kW), max ₹78,000 (≥3 kW) for residential connections. |
| Net Investment | ₹ (INR) | Effective consumer investment out of pocket after deducting applicable central government subsidies. |
| Monthly Savings | ₹ / Month | Direct utility bill reduction from self-consumed solar electricity and net-metered energy export. |
| Estimated Payback | Years | Simple investment recovery breakeven period (Net Capex ÷ Annual Electricity Savings). |
| 25-Year Net Savings | ₹ (INR) | Cumulative financial gain over 25-year lifecycle factoring 0.7% annual panel degradation and 3% tariff inflation. |
Solar Calculator for India — Key Scenarios
Solar Calculator by Bill
For a ₹3,000 bill (~400 units), a 3 kW system is ideal. For a ₹5,000 bill (~650 units), a 4.4 to 5 kW system offsets over 80% of power costs.
Solar Calculator by Units (kWh)
Inputting actual meter units (kWh) eliminates fixed charges and tiered slab variance, producing maximum mathematical precision.
Solar Calculator for Home
Most Indian standalone villas and row houses install 3 kW to 5 kW systems, receiving up to ₹78,000 central subsidy with a ~3.2-year payback.
Solar Calculator in kW
1 kW produces ~4.2 kWh daily (~1,500 units/yr). 5 kW produces ~21 kWh daily. Commercial 10 kW generates ~15,000 units annually.
Frequently Asked Questions
Verified technical guidance from IISE solar engineering faculty.
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Solar Cost Calculator
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Determine exact recovery month after PM Surya Ghar subsidies.
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