Solar Rooftop· Green Energy
Solar Rooftop & Panel Size Requirement Calculator
Plan your on-grid or hybrid solar rooftop system based on your monthly electricity bill. Calculates recommended solar kW size, monthly units generated, required shadow-free roof area (sq. ft), and PM Surya Ghar subsidy estimate.
Recommended Solar System
3.7 kW
Requires 7 panels (540W Mono PERC Bifacial).
Required Roof Space:333 sq. ft
Est. Annual Bill Savings:₹41,940/yr
PM Surya Ghar Subsidy:₹78,000
Covers ~90% of your current monthly electricity bill
Monthly Electricity Bill
₹3,500₹1,000 (1 BHK)₹5,000 (3 BHK + AC)₹20,000 (Bungalow)
Estimated Units Consumed:467 kWh / month
Solar Panel Type
540W Mono PERCAverage Indian sunlight yields 4.0 to 4.5 peak sun hours daily, generating ~120 to 130 units per kW each month.
How This Calculation Works & Technical Formula
Solar System (kW) = (Monthly Units / 30 days) / 4.2 average peak sun hours. Roof Area = System kW × 80 to 100 sq. ft per kW.
How to use this tool:
- Enter your average monthly electricity bill (₹) or monthly units consumed (kWh).
- Select your panel technology (e.g. 540W Mono PERC bifacial or standard 400W).
- View recommended Solar kW size, required shadow-free terrace area, and government subsidy estimate.
Frequently Asked Questions
How much roof space is required for a 3kW solar system?+
A 3kW solar rooftop installation typically requires about 240 to 300 square feet of shadow-free terrace space using modern high-efficiency 540W Mono PERC panels (around 6 panels total).
Other Power Backup Calculators You Might Need
View All 10 Tools →Inverter & Battery
Inverter Size Calculator
Find the exact Inverter VA rating required for your home appliances
Try Tool →
Inverter & Battery
Battery Backup Time
Calculate exact backup hours & minutes based on battery Ah & running load
Try Tool →
Inverter & Battery
Battery Charging Time
Know charging hours & electricity bill units consumed per full charge
Try Tool →