AC vs DC charging, and single vs three-phase power

Batteries store DC electricity. The grid supplies AC. Somewhere, AC has to be turned into DC, and where that happens decides how fast you can charge.

AC charging

The charger passes AC to the car, and the car's own on-board charger converts it. A Model 3 or Model Y's on-board charger can take up to 11 kW. AC chargers are at homes, workplaces, hotels, car parks and on streets.

DC charging

The charger converts AC to DC itself and sends DC straight to the battery. Big converters in the charger allow much higher power: 50 kW at older rapid chargers, 150 to 350 kW at ultra-rapid ones and up to 250 kW for a Tesla at a Supercharger.

Single-phase and three-phase

• Single-phase is what most UK homes have. The most a 32 A single-phase supply can give is about 7.4 kW.
• Three-phase is common in businesses and some newer or larger homes. It can give 11 kW or 22 kW.

So a "22 kW" public charger gives a Tesla 11 kW (its on-board limit), and a "7 kW" home charger gives about 7 kW whatever the car.

Which is cheaper?

AC charging at home on an EV tariff is usually the cheapest way to charge. Public AC chargers can be cheaper or dearer than rapid chargers depending on the network. Rapid DC charging costs more but saves time on trips. See Tesla charging costs.