Payback (years) = (Install cost − subsidy) ÷ Annual savings. Annual generation ≈ system kW × specific yield (kWh/kW/year). Typical specific yield: 1300–1600 in India, 1100–1400 in temperate climates.
Payback period
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Net cost after subsidy
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Annual generation
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Annual savings
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25-year total savings
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Net ROI (25 yr)
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Assumptions
Solar panels are warrantied for 25 years with typical degradation 0.5%/year — this calculator assumes flat output for simplicity (real savings will be ~5–10% lower).
Net metering pays out unused units; assumes 100% self-consumption or full net-metering credit.
Inverter replacement (~₹15,000–30,000) at year ~10 is not included.
India residential subsidies under PM Surya Ghar (2024) are typically 30–40% of install cost up to 3 kW; check current scheme.