ROI calculator
Is solar a good investment for you?
Clean Energy. Smarter Future.
Year-by-year cash flow, payback, NPV and IRR — for paying in cash and for financing with a loan, side by side. Every input is yours to change.
Navya Solar — Solar ROI summary · navyasolar.in · +91 85001 25888
Printed . Estimates only — not a quotation or performance guarantee.
Simple payback
—
Net present value
—
IRR
—
Net cash gain
—
Upfront outlay
—
Discounted payback
—
Year-1 savings
—
Levelised cost (LCOE)
—
Cash flow and cumulative position
- Annual cash flow
- Negative year
- Cumulative — cash
- Cumulative — loan
Cash vs. loan
| Metric | Cash | Loan |
|---|
Loan details
- Net cost after subsidy—
- Loan principal—
- Monthly EMI—
- Total interest—
- 25-year gross savings—
Year-by-year cash flow
| Year | Production (kWh) | Savings | Maintenance | Inverter | Loan payments | Net cash flow | Cumulative |
|---|
Methodology, formulas & assumptions
Annual cash flow (year t = 1…N)
Productionₜ = Production₁ × (1 − degradation)^(t−1)
Savingsₜ = Productionₜ × [Self-use % × Tariff × (1 + escalation)^(t−1) + (1 − Self-use %) × Export rate]
O&Mₜ = O&M₁ × (1 + O&M inflation)^(t−1)
Inverterₜ = Replacement cost × (1 + O&M inflation)^(t−1) in the replacement year, else 0
Operating CFₜ = Savingsₜ − O&Mₜ − Inverterₜ
Cash case
CF₀ = −(Installed cost − Subsidy); CFₜ = Operating CFₜ
Loan case (financing cash flows counted once)
Loan = min(Loan amount, Installed cost − Subsidy)
EMI = L·r ÷ (1 − (1 + r)^−n), r = annual rate ÷ 12, n = years × 12
CF₀ = −(Installed cost − Subsidy − Loan) ← down payment only
CFₜ = Operating CFₜ − 12 × EMI (during the loan tenure)
Metrics
NPV = Σ CFₜ ÷ (1 + discount)^t, t = 0…N
IRR = rate where NPV = 0 (bisection; shown only when the series supports it)
Simple payback = time until cumulative cash flow first returns to ≥ 0 (interpolated)
Discounted payback = same, using discounted cash flows
LCOE (cash case) = [Net cost + PV(O&M + inverter)] ÷ PV(production)
- Taxes, depreciation benefits, insurance and battery replacement are not modelled.
- The subsidy is treated as received at year 0 and only if you enter it. No subsidy amount is assumed by default.
- IRR is not shown when there is no upfront investment (e.g. 100% financed) or when cash flows never turn positive; NPV remains valid.
- All figures are nominal rupees. Results are estimates, not financial advice.
This tool gives indicative financial estimates only and is not financial advice, a loan offer or a performance guarantee.