☀️ Free Online Tool
Solar Rooftop
System Calculator
Estimate your solar system size, panel count, roof area, cost, savings, and payback period — instantly and accurately.
Enter Monthly Electricity Bill
We’ll estimate the ideal solar system size to offset your electricity expenses.
Indian Rupees per month
Peak Sun Hours: 4.8 h/day
▶ Advanced Options (Optional)
Your current rate per unit
Per panel capacity
Connection type
Typical: 18–22%
Dust, cable, inverter losses
Typical: 0.5% per year
Installed cost per kWp
Government subsidy available
Expected electricity rate rise
System Size
—
kWp
No. of Panels
—
panels
Est. System Cost
—
after subsidy
Roof Area Required
—
approx. m²
Monthly Generation
—
kWh / month
Annual Generation
—
kWh / year
CO₂ Offset
—
kg CO₂ / year
Payback Period
—
years
25-Year Savings
—
approx. total
💰 Savings Breakdown
Monthly Savings
—
₹ / month
Annual Savings
—
₹ / year
ROI (25 Years)
—
% return
📋 Complete System Specifications
| Parameter | Value | Parameter | Value |
|---|---|---|---|
| System Capacity | — | Panel Type | — |
| No. of Solar Panels | — | Panel Wattage | — |
| Inverter Capacity | — | System Type | — |
| Roof Area Required | — | Peak Sun Hours | — |
| Annual Generation | — | Performance Ratio | — |
| Gross Cost | — | Subsidy Amount | — |
| Net Cost (After Subsidy) | — | Payback Period | — |
ℹ️ Disclaimer: These calculations are estimates based on standard assumptions (density 7850 kg/m³, typical solar irradiance data). Actual generation may vary by ±15% depending on shading, panel orientation, tilt angle, local weather, and equipment quality. For a precise technical assessment and quotation, please contact ECS Engineering.
☀️ How Solar Works
Solar Panels Generate DC Power
Photovoltaic (PV) panels convert sunlight into DC electricity. A 545 Wp panel generates about 2.2–2.6 kWh per day in good sun conditions.
Inverter Converts to AC Power
The string inverter or microinverter converts DC to 230V AC power for home/office use. On-grid systems export surplus to the grid (net metering).
Net Metering Saves Money
Surplus units exported to grid are credited to your bill. On-grid systems can reduce your electricity bill to near zero if sized correctly.
PM Surya Ghar Subsidy
Government provides 30% subsidy on 1–3 kW systems and 15% on 3–10 kW systems under PM Surya Ghar Muft Bijli Yojana for residential consumers.
Roof Area Rule of Thumb
Approximately 8–10 m² of shadow-free roof area is required per kWp of solar installation (depends on panel type and mounting structure).
Payback Period
A typical residential on-grid solar system pays back in 4–6 years and generates free electricity for the remaining 20+ years of its 25-year warranted life.
☀️ Want a Precise Solar Assessment?
ECS Engineering provides complete solar rooftop design, DPR, and installation support — with subsidy assistance and net metering documentation.
