20 kW DC or 22 kW AC for a home or small site?

Most home and small-site charging is AC, and for good reason: it is simple, it uses the supply that is already there, and cars sit parked long enough for it to work. A DC charger earns its place when the parking window is short and the vehicle’s AC intake is the bottleneck.

Why DC can charge faster on the same car

On AC, the vehicle’s on-board charger sets the limit — often 7 to 11 kW. A DC charger converts the power outside the vehicle and feeds the battery directly, so the on-board charger is no longer the constraint. A 20 kW DC unit can therefore deliver more than a 22 kW AC point to a car that only accepts 11 kW on AC.

What 20, 30 and 40 kW DC is for

These are not motorway fast chargers; they are small-site units. Typical fits: a home with a large battery and a short overnight window, a workshop or depot where vehicles rotate during the day, a destination site that wants a meaningful top-up in an hour or two, or a site where a three-phase AC upgrade is impractical.

AC and DC side by side

• AC is usually the lower-cost, lower-complexity route, and load balancing can share a limited supply across several points.
• DC delivers more energy per hour, but the input still has to be sized for the output — a 20 kW DC charger is not a way to create power the site does not have.
• Mixed sites are common: AC for long-stay bays, one DC unit for vehicles that need to leave quickly.

The questions that decide it

• How long does a vehicle actually stay? Under two hours, DC starts to pay; all night, AC is usually enough.
• What does the vehicle accept on AC, and on DC?
• What supply is available, and what else shares it?
• Which connector standard do the vehicles use?

If the answers point to DC, the next question is output: 20 kW covers a single-car top-up; 30 and 40 kW suit small fleets and busier sites. If the site has one three-phase supply and several cars, AC with dynamic load balancing is often the more practical design — it uses the supply that exists instead of requiring an upgrade.

Standard models are CE and RoHS compliant. Customised builds require additional CE and RoHS certification, which we confirm at quotation.

Next step: see the 20/30/40 kW DC charger, the European AC charger and the DLB AC charger, or send us the site details — supply, vehicles and parking pattern — and we will recommend a configuration.

Shenzhen Holeetech Co., Ltd. manufactures AC and DC charging equipment in-house.