xcalc — ROI / Payback

Inputs

Max kW / location

Installed maximum charging power at one location.

Charging hours per day / location

Example: 4 hours/day ⇒ 4 / 24 = 16.7% utilization.

Number of locations

Margin (profit) per kWh (€)

Net margin after all variable costs.

CAPEX per location (€)

OPEX per location per year (€)

Fixed yearly costs (rent, service, connectivity, etc.).

Outputs

Theoretical kWh / day / location

—

Utilization

—

Actual kWh / day / location

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Annual gross margin

—

Annual OPEX

—

Annual net profit

—

Total CAPEX

—

Payback (years)

—

Formula:
theoreticalKwhDay = maxkW × 24
utilization = hoursPerDay / 24
actualKwhDay = theoreticalKwhDay × utilization
annualGross = actualKwhDay × 365 × locations × margin
annualNet = annualGross − (opex/location/year × locations)
paybackYears = totalCapex / annualNet

Examples around base case (9 variants)

Varies only margin €/kWh (±0.01) and hours/day (±1). All other inputs fixed.

Margin €/kWh	Hours/day	Actual kWh/day	Utilization	Annual gross	Annual net	Payback (y)