A demand charge is a fee on many commercial electricity tariffs based on the highest power, in kilowatts, that a site draws during a billing period. It sits on top of the per-kilowatt-hour energy charge. Because one short fast-charging session can set that peak for the whole month, demand charges are often the least expected cost of running commercial EV chargers.
Key Takeaways
- A demand charge prices your highest kW peak in the billing period, not your total energy.
- One fast-charging session, or many Level 2 posts at once, can set the peak for a month.
- Load management, staggered schedules, and the right charger power keep peaks deliberate.
- Find the demand line on your current bill before sizing a charging project.
Energy Charges and Demand Charges Are Different
| Energy charge | Demand charge | |
|---|---|---|
| Measures | Total electricity used (kWh) | Highest power drawn at any moment (kW) |
| Driven by | How much charging you sell or use | How much charging happens at the same time |
| Set by | Every session, added up | Usually the single highest interval in the month |
Utilities measure the peak over a short interval, often 15 or 30 minutes, but the exact interval and the price per kW vary by tariff. Both figures appear on a commercial bill, and the first step is to find the demand line on yours and see which tariff your site is on.
Why EV Charging Sets Peaks So Easily
A charger draws high power by design. Under NEVI rules, a corridor DC port delivers at least 150 kW, so a single car plugging in can lift a site’s peak by 150 kW in seconds. Level 2 charging is gentler but adds up: ten 7 kW posts running together draw about 70 kW. The peak is set by the worst moment of the month, not the average day, which is why a busy half hour can cost more than a quiet week of charging. Our overview of how commercial EV charging stations work covers the hardware and software behind this.
Ways Site Hosts Keep the Peak Down
- Match power to dwell time: cars parked for hours do not need DC speed; Level 2 spreads the same energy over more time at lower power.
- Use load management: networked chargers share a capped power budget, so the site peak stays at a level you choose.
- Stagger fleet charging: schedule vehicles to start in sequence overnight instead of all at shift end.
- Check the tariff before installing: some utilities offer EV or off-peak commercial rates; a short call before installation is cheaper than a surprise bill after it.
- Size for the peak, not just the energy: include demand charges in the running-cost estimate, alongside the hardware figures in our guide to how much commercial EV chargers cost.
These steps reduce the peak; they do not remove the charge. As our explainer on why DC fast charging is so expensive notes, demand charges are one of the main costs public operators have to recover in their prices.
Hardware That Helps
Power sharing is built for this problem. The EV-AC03201T dual-connector AC station shares up to 43 kW across two connectors and connects over OCPP 1.6J, so a management platform can cap and schedule output. More options for shared sites are on our commercial EV charging page.
Frequently Asked Questions
Do all businesses pay demand charges?
No. They are common on medium and larger commercial tariffs and rare on small ones. Check your bill or ask your utility which tariff applies to your meter.
Is a demand charge based on kWh?
No. It is based on kW, the peak rate of draw, measured over a short interval. Two sites can use the same monthly kWh and pay very different demand charges.
Can load management eliminate demand charges?
It cannot remove them, but it caps the peak your chargers can create, which keeps the charge predictable instead of letting one busy period set it.
Related Reading
- How Much Do Commercial EV Chargers Cost?
- Why Is DC Fast Charging So Expensive?
- How Do Commercial EV Charging Stations Work?
- Smart Charging and Time-of-Use Tariffs: How Scheduling Cuts EV Charging Costs
