Charger utilisation is the share of a charger’s available time, or of its rated energy output, that drivers actually use. Operators measure it two ways: time utilisation counts the hours a port is occupied, while energy utilisation compares the kilowatt-hours sold with the maximum the unit could have delivered. It is the number that decides whether a site’s fixed costs get covered, because a charger only earns while a car is drawing power.
Key Takeaways
- Utilisation is measured two ways: by time connected and by energy sold.
- The two numbers can differ widely for the same charger on the same day.
- Fixed costs run every month; only energy sold pays for them.
- Drivers see occupancy; operators budget on the energy measure.
The Two Measures, Side by Side
Neither measure is wrong. They answer different questions, and confusing them is how a site that looks busy ends up losing money.
| Measure | How it is counted | What it shows | What it hides |
|---|---|---|---|
| Time utilisation | Hours a port is plugged in, out of 24 | How occupied the bay is | Whether power was actually flowing |
| Energy utilisation | kWh sold, divided by rated kW × 24 hours | How much of the hardware’s capacity was sold | How long cars sat connected |
One Charger, Two Very Different Numbers
Take a labelled example. A 7 kW Level 2 port — inside the U.S. DOT’s typical 7–19 kW Level 2 band — is plugged in for 4 hours a day and sells 15 kWh in that time. Its time utilisation is 4 out of 24 hours, about 17%. Its energy utilisation is 15 kWh out of a theoretical 168 kWh (7 kW × 24 hours), about 9%. Same charger, same day, two numbers — and the energy figure is the one tied to revenue.
Why the Gap Opens Up
- Cars stay plugged in after charging finishes, so occupied hours grow faster than energy sold.
- Charging slows as the battery fills, so the later hours of a session deliver less than the nameplate rate.
- The car often sets the pace: a lower-rated onboard charger caps what a higher-rated port can sell.
- Dual-connector units can share power between two cars, so one busy connector does not mean the unit is at full output.
Why Operators Watch the Energy Figure
Software, connectivity, maintenance and site upkeep arrive every month whether or not anyone plugs in, and demand charges follow the site’s peak draw rather than its sales. Energy sold is what pays for all of it: electricity bought at the commercial rate — the U.S. average is 14.53 cents per kWh, per the EIA — and resold under the structures in our guide to how much EV charging stations charge. The full profit model, run at several utilisation levels, is in our piece on whether an EV charging station business is profitable; this article only defines the measure behind it.
Drivers see the time side — a charger that looks always busy or always empty. Operators budget on the energy side. The classic gap is a workplace port occupied all day by one car that finished charging mid-morning: full marks for occupancy, very little energy sold.
Hardware That Lifts Utilisation Per Connection
Two design choices help. Serving two cars from one connection spreads the fixed costs: the EVDANCE EV-AC03201T dual-connector AC station runs two Type 2 connectors sharing up to 43 kW, 22 kW per connector. Where faster turnover matters, the EV-RHDC30K-L compact DC fast charger delivers 22 kW DC, so each occupied hour sells more energy. Both run OCPP 1.6J, and the session data the platform collects is what makes either measure possible — see our explainer on OCPP for charge point operators. The commercial charging solutions page covers site planning.
Frequently Asked Questions
What is a good utilisation rate for a public charger?
There is no official benchmark figure. The level a site needs depends on its own costs and prices: a charger covers its fixed costs at the point where its energy margin matches them, and that point differs by site, charger type and tariff.
Why does the app show a charger as busy when its utilisation is low?
Because apps show occupancy, which is the time measure. One car plugged in blocks the port whether it is drawing full power or nothing at all, so a port can read “busy” all day on a single session.
Does higher utilisation always mean more profit?
No. Queues turn drivers away, wear rises, and many sessions at once can lift the site’s peak demand charge. The energy margin — not occupancy alone — is the test that matters.
Related Reading
- Is an EV Charging Station Business Profitable?
- How Much Do EV Charging Stations Charge? Pricing Models Explained
- Where to Install an EV Charging Station: Site Selection Guide
- OCPP Explained: What Charge Point Operators Need From EV Charger Hardware
