Model methodology

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This page publishes the formulas, conventions, scenario multipliers and sources behind the EV Charging ROI Calculator (engine v2.2.0), so every number on the dashboard can be traced and challenged. The engine is unit-tested, including golden tests against the reference franchise case; independent review by a project-finance and a tax professional is recommended before large commitments.

Conventions

Demand & energy

delivered kWh = rated kW × chargers × hours/day × days/mo × uptime × utilization
grid kWh      = delivered ÷ (1 − losses) + auxiliary kWh
sessions      = delivered ÷ kWh per session

Ownership model

blended price   = retail × (1 − fleet share) + fleet price × fleet share
net revenue     = delivered × blended price × (1 − commissions% − land share%)
electricity     = grid × energy charge × (1 + duty%) + fixed charges + demand charge × kVA   (structured mode)
                = grid × landed tariff                                                       (flat mode)
EBITDA          = net revenue − electricity − variable opex − fixed opex (incl. land rent / opportunity cost, post-warranty step-up)
project FCF     = EBITDA − unlevered tax ± dated items (replacement, expected subsidy, ITC, deposits)
equity FCF      = EBITDA − interest − principal − levered tax ± dated items
tax             = WDV depreciation per asset-class line (per-line rate override, else global), net of ITC, with loss carry-forward
CFADS           = EBITDA − cash taxes − replacement capex   (subsidy/ITC treated as restricted and excluded;
                  working-capital movements are not modelled)
CFADS DSCR      = CFADS ÷ (interest + principal)   — the lender measure driving bankability verdicts
EBITDA DSCR     = EBITDA ÷ (interest + principal)  — the broad measure, shown for reference
residual value  = residual % × cash cost of residual-ELIGIBLE physical assets only (soft costs excluded)
LCOC            = PV(capex + all operating costs + tax) ÷ PV(delivered kWh)
break-even util = (fixed costs + fixed electricity + aux cost) ÷ (full-utilization kWh × margin/kWh)
                  — quoted both without and with monthly debt service (EMI)

Franchise model

One of two payout waterfalls is selected explicitly — they are never combined:

A) MAX waterfall:        payout = MAX(minimum guarantee, distributable cash × investor share)
B) Guarantee + excess:   payout = minimum guarantee + MAX(units − threshold, 0) × excess rate

guarantee top-up (franchisor obligation) = MAX(guarantee − entitlement⁺, 0)
contractual terminal = buyback base × buyback %          (base: ex-GST / incl-GST / fixed — always explicit)
risk-adjusted terminal = contractual × recovery %
total ROI = net profit ÷ investment paid;  MOIC = total received ÷ invested (never called ROI)
full obligation coverage = station operating cash ÷ (all investor payouts + terminal)

Three return views, never conflated:

Contractual:      every promised rupee is paid on time
Credit-adjusted:  each future flow × survival(month), survival = (1 − monthly hazard)^month,
                  monthly hazard = 1 − (1 − annual default probability)^(1/12);
                  the terminal is floored at MIN(secured amount, contractual terminal) when
                  hard security (deposit / escrow / bank guarantee) is entered
After-tax:        monthly income × (1 − tax rate); terminal treated as capital return (verify with tax adviser)
Real IRR:         (1 + nominal IRR) ÷ (1 + inflation) − 1

Scenario multipliers

Scenarios re-run the full engine on adjusted inputs — they never scale final outputs. The exact multipliers:

ScenarioDemandPriceEnergy costFixed opexCapexUptimeBuyback recovery
Stress×0.55×0.9×1.1×1.1×1.15×0.93×0.5
Conservative×0.8×0.95×1.05×1.05×1.05×0.97×1
Base×1×1×1×1×1×1×1
Strong site×1.3×1.05×1×0.98×1×1×1

Model checks

Checks are grouped into input validity (failures block all results), arithmetic reconciliation, operating viability, investor attractiveness (NPV vs your hurdle, IRR, payback source) and bankability (DSCR, obligation coverage). Reconciliation passing never implies the investment is attractive.

Assumption sources

Known limitations

Version history