Home/Environmental Tools/Solar Panel ROI Calculator
Renewable Energy

Solar Panel ROI Calculator

Estimate your solar payback period, 25-year savings and CO2 reduction from system size, installation cost, sun hours and your electricity rate.

Advertisement
Solar Panel ROI Calculator
Calculate payback period, savings and CO₂ reduction from going solar
4.5h
Payback Period
—
Net System Cost—
Annual Generation—
Annual Savings—
25-Year Savings—
25-Year ROI—
CO₂ Saved/Year—
🌞 Note: Solar output varies by location, panel orientation and shading. Add battery storage to increase self-consumption and savings.

Disclaimer. Solar generation, savings and payback estimates depend on location, panel orientation, shading and your entered electricity rate assumptions; get a site-specific quote from a solar installer before making a purchase decision. Read full disclaimer →

About Solar Panel Calculator

Solar panel daily output formula: Daily kWh = System kWp times Peak Sun Hours times System Efficiency. System efficiency is typically 75-80% accounting for inverter losses, wiring losses, dust, and temperature derating. India receives 4.0-5.5 peak sun hours per day depending on location - highest in Rajasthan and Gujarat, lowest in the North-East.

Financial analysis: typical installed cost is Rs 45,000-65,000 per kWp after PM-Surya Ghar subsidy. Government subsidy: Rs 30,000 for 1 kWp, Rs 60,000 for 2 kWp, Rs 78,000 for 3 kWp or more for residential customers. Payback period is typically 4-6 years. Net metering allows selling surplus generation to the grid at Rs 3-5 per unit. System life is approximately 25 years with less than 0.5% annual output degradation. Annual savings equal total output in kWh multiplied by your grid electricity tariff.

Formula Used In This Calculator

Annual Generation (kWh) = System Size (kW) × Daily Peak Sun Hours × 365 × 0.8 system efficiency. The calculator assumes 70% of generation is self-consumed (valued at your electricity rate) and 30% is exported (valued at your feed-in tariff), then projects year-by-year savings for 25 years with your entered annual rate increase compounding each year, to find the payback year where cumulative savings cover your net system cost (installation cost minus subsidy). CO₂ saved per year uses the same 0.436 kg CO₂/kWh grid emission factor as the carbon footprint calculator.

Frequently Asked Questions

Annual Generation = System Size (kW) x Daily Peak Sun Hours x 365 days x 0.8 system efficiency. The 0.8 efficiency factor accounts for real-world losses from the inverter, wiring, dust accumulation and heat, which typically total 20-25% versus a panel's rated lab output.
The tool assumes 70% of your solar generation is used directly in your home (valued at your electricity rate) and 30% is exported to the grid (valued at your feed-in tariff, which is often lower than your electricity rate). This self-consumption ratio is a typical planning assumption -- your actual split depends on your usage patterns relative to when the sun is generating power.
The calculator projects savings year by year for 25 years, compounding your electricity rate by your entered annual rate increase each year, and finds the first year where cumulative savings equal or exceed your net system cost (installation cost minus any subsidy). A higher annual rate increase assumption shortens the projected payback period.
The calculator uses 0.436 kg CO2 per kWh, an IEA global average grid emission factor, multiplied by your annual generation. Your actual CO2 savings will be higher or lower depending on how carbon-intensive your specific regional electricity grid is -- grids with more coal generation see bigger emissions savings from solar, while already-clean grids see smaller savings.
Advertisement

Related: Home Energy Bill Calculator, Carbon Footprint Calculator, All Environmental Tools