Commercial EV charger demand charge calculator
Estimate the monthly electricity cost of a workplace, fleet, hotel, retail, or public charging site. See how charger power, utilization, concurrency, and managed charging can change demand exposure.
Commercial EV charger cost calculator
Estimate energy, demand, and network costs for a workplace, fleet, or public charging site. Replace every default with values from your charging logs and utility tariff.
Six 50 kW ports with a 150 kW managed limit
Six ports delivering an average of 180 kWh per port per day for 30 days produce 32,400 kWh per month. At $0.12/kWh, the energy charge is $3,888. A 70% simultaneous-use assumption would create a 210 kW charging peak, but a 150 kW managed limit reduces the modeled demand charge to $2,700 at $18/kW. With $450 in network and fixed fees, the illustrative monthly total is $7,038, or about $0.22 per delivered kWh.
Energy use and peak demand answer different questions
Kilowatt-hours measure the energy delivered over time. Kilowatts measure power at a moment or over a utility-defined interval. A site can deliver the same monthly energy with very different peaks depending on how many ports charge together and how quickly each vehicle must be served.
The U.S. Department of Energy's Alternative Fuels Data Center notes that charging costs depend on equipment type, time of use, and charging duration. It also identifies DC fast charging as more likely than Level 1 or Level 2 charging to trigger demand charges. Always read the utility's current commercial EV tariff rather than assuming a generic demand rate.
Inputs to collect before evaluating a charging site
| Input | Best source | Why it matters |
|---|---|---|
| Delivered kWh | Charging-network export | Determines energy sales and volumetric cost. |
| 15-minute site peak | Utility interval data | Shows whether charging establishes a new billed peak. |
| Port concurrency | Session timestamps | Separates installed capacity from likely simultaneous load. |
| Vehicle dwell time | Fleet or customer data | Defines how much power can be shifted without missed departures. |
| Tariff rules | Utility rate sheet | Controls time-of-use, demand, ratchet, and seasonal billing. |
How to test a managed-charging limit
- Export at least one complete billing cycle of charging sessions.
- Align charging data with the building's interval load.
- Identify the actual interval that established billed demand.
- Test lower site limits against vehicle departure requirements.
- Confirm whether another facility load would still set the peak.
Managed charging is not simply reducing every charger's rating. A useful control plan allocates available power based on vehicle energy requirements, departure times, building load, and tariff periods. A battery or solar array may provide additional options, but each requires a separate capital-cost and operational analysis.
Frequently asked questions
How are commercial EV charger demand charges calculated?
A utility commonly multiplies the highest qualifying demand interval during the billing period by a dollar-per-kilowatt rate. The exact interval, ratchet, seasonal rules, and coincident or noncoincident treatment come from the tariff.
Why can a low-use fast-charging site have a high cost per kWh?
A short high-power charging event can establish the billed peak even when monthly energy sales are modest. Dividing that demand charge across relatively few delivered kilowatt-hours can produce a high all-in electricity cost.
Can managed charging reduce demand charges?
It can when charging power can be limited or sequenced below the peak that would otherwise be billed. Savings depend on the tariff, existing building load, vehicle dwell time, required energy, and whether another load still sets the monthly peak.
Does this calculator include charging-station revenue?
No. It estimates selected electricity and network costs. Hardware, installation, maintenance, payment processing, taxes, downtime, parking, depreciation, incentives, and customer revenue require a separate business model.