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AC vs DC EV charging: which does your site need?
The decision is not about charging speed. It is about how long vehicles stay — and getting that wrong is the most expensive mistake in EV charging site planning.
The short answer
Match the charger to dwell time. If vehicles are parked for two hours or more, AC is almost always right — the car is there long enough, and AC costs a fraction as much to buy, install and run.
DC earns its cost where turnaround matters — highway corridors, taxi fleets, commercial vehicles on tight cycles. Anywhere a driver is waiting with the vehicle rather than doing something else.
A DC charger at a workplace where cars sit all day delivers nothing an AC unit would not, while consuming capital and supply capacity you will want for more charging points later.
Side by side
What separates them from a site owner's point of view rather than a driver's.
| Consideration | AC charging | DC fast charging |
|---|---|---|
| Where conversion happens | In the vehicle's onboard charger | In the charger itself |
| Typical power range | 3.3 kW – 22 kW | Tens to hundreds of kW |
| Charging speed | Hours | Minutes to under an hour |
| Capital cost per point | Low | Substantially higher |
| Electrical supply needed | Often within existing capacity | Usually a new connection or upgrade |
| Civil and installation work | Modest | Significant |
| Ongoing servicing | Minimal | Meaningful — active cooling, power electronics |
| Maximum rate is limited by | The vehicle's onboard charger | The charger and the vehicle |
| Suits dwell time of | Two hours or more | Under an hour |
| Best fit | Workplaces, homes, malls, hotels, fleet depots overnight | Highway corridors, taxi and fast-turnaround fleets |
Decide by dwell time
Eight hours — workplace, apartment, hotel
AC, and probably at a lower rating than you think. Vehicles have all night or all day; the constraint is how many points you can serve, not how fast each one goes.
Two to four hours — mall, cinema, restaurant
AC at 7.4 kW to 22 kW. Long enough to add meaningful range, and the charging becomes an amenity rather than the reason for the visit.
Under an hour — highway stop, taxi rank
DC. This is the case AC cannot serve, because the driver is waiting rather than doing something else.
Fleet depot, overnight
AC with load management. Vehicles return in the evening and leave in the morning; spreading the charging across those hours avoids a supply upgrade entirely.
Mixed-use, larger site
Both, in the right ratio — a small number of DC points for short-stay visitors, AC for everyone else. One management system can run both if they speak OCPP.
Where we stand, plainly
Tech OVN manufactures AC chargers only — 3.3 kW to 22 kW — along with the charge point management system that runs them. We do not make DC fast chargers.
We would rather say that than have you find out later. If your site genuinely needs DC, we will tell you, and you should buy it from someone who makes it.
What we see often, though, is a site that believes it needs DC and actually needs more AC points. Cars in an office car park are not waiting to charge — they are parked. Serving twelve of them on AC usually beats serving two on DC, for less money and without a supply upgrade.
Frequently asked questions
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Tell us the parking pattern and your spare electrical capacity. We'll tell you what to install — including when the answer isn't us.