Most EV owners do almost all of their charging at home, overnight or while the sun is up, and rarely visit a public charger. How long it takes depends on just two numbers: how much energy the car needs, and how fast your home can supply it.
The sum
hours to charge = kWh needed ÷ charging power (kW)
Then add about 10% for losses: some energy turns into heat in the charger, cables and battery. The car's battery is measured in kilowatt-hours, the charger in kilowatts. If that distinction is new, the three-minute kW vs kWh explainer covers it.
For example, putting 30 kWh into a car with a 7 kW charger takes 30 ÷ 7 = 4.3 hours, so about 4.5–5 hours in practice.
How fast is each kind of home charging?
How you charge | Typical power | Range added per hour (at 16 kWh/100 km) |
|---|---|---|
Australian 10 A wall socket | about 2.3 kW | about 13 km (8 miles) |
US Level 1 (120 V socket) | 1.2–1.9 kW | about 8–11 km (5–7 miles) |
Single-phase wallbox (US Level 2) | about 7 kW | about 40 km (25 miles) |
Three-phase wallbox | 11 kW | about 65 km (40 miles) |
The range figures assume an efficiency of 16 kWh per 100 km (about 3.9 miles per kWh), typical for a mid-size electric car. A big SUV or ute will add less range per hour; a small hatchback, more. Check your own car's figure in its trip computer. For choosing a car, range and running costs on the road, see Cole's sister site, Sweet Commute. It also has a guide to e-bikes, which charge from a normal socket and need about 1 kWh per 100 km.
What limits the speed?
Charging runs at the speed of the slowest link in the chain:
- Your home's supply. A standard socket on its own circuit, or a dedicated circuit for a wallbox. A three-phase supply is needed for 11 kW and above.
- The charger or cable. Wallboxes are commonly rated at 7 kW single-phase or 11–22 kW three-phase.
- The car's onboard charger. For home (AC) charging, the car converts the power itself, and many cars can only accept 7 or 11 kW on AC, whatever the wallbox can do. Check your car's AC charging limit before paying for a faster charger.
The car's battery also slows charging as it gets close to full, but at home charging speeds the effect is small.
How much charging do you actually need?
Probably less than you think. Most people don't drain the battery each day; they top up what they used.
daily kWh = daily km × kWh per 100 km ÷ 100
At 40 km (25 miles) a day and 16 kWh/100 km, that's 6.4 kWh a day:
- about 3 hours on a 10 A socket;
- under 1 hour on a 7 kW wallbox.
That's why many owners manage happily on a standard socket, especially with a short commute and the car parked at home overnight. A wallbox is worth considering if you drive long distances most days, have two EVs, or want to charge quickly in a short solar or off-peak window.
Does charging at home need a wallbox?
Not necessarily. The portable cable supplied with many EVs plugs into a normal socket. Have an electrician check the socket and circuit first, because charging draws a lot of current for hours at a time, and older wiring may not be up to it.
A wallbox adds speed, a tidier installation and, often, smart features: scheduling, load management that slows charging when the house is drawing a lot, and solar charging. Installed prices vary widely with the distance from the switchboard and whether the switchboard needs upgrading. Get a quote for your home rather than relying on an advertised price.
Charging from your own solar
This is where an EV and rooftop solar really suit each other. Solar power you'd otherwise export for a few cents per kWh can drive the car instead, and the saving per kWh is the gap between petrol (or a public charger) and your feed-in tariff.
The challenge is matching the car's charging to the sun:
- The car has to be home and plugged in during the day. Easy if you work from home or have a second car; harder if the EV is your commuter.
- The charging rate should follow the spare solar. A plain charger draws a fixed amount, so when a cloud passes or the oven goes on, the shortfall comes from the grid. A solar-aware charger (or a car and app that can do the same) varies the charging rate to match your spare solar.
- The minimum current. Most cars need at least about 1.4 kW (single-phase) before they'll charge. On a dull winter day there may not be that much spare.
On a sunny day, a 6.6 kW system with a few kW to spare can put 10–20 kWh into a car between mid-morning and mid-afternoon: 60–120 km (40–75 miles) of driving, from sunshine that would otherwise earn very little.
Charging overnight on a cheap rate
If the car is away during the day, the next best option is often an off-peak or EV tariff, with cheap power overnight. Set the car or charger to start in the cheap window. Our guide to reading your bill explains how time-of-use pricing works, and why it matters which hours you charge in.
A home battery can also store daytime solar for the car overnight. It works, but the losses add up and the battery's capacity is often better spent running the house in the evening. Charging the car directly from solar or off-peak power is usually cheaper.
What does a charge cost?
cost = kWh × price per kWh
At 6.4 kWh a day:
- off-peak at 20c per kWh: about $1.30 a day;
- spare solar that would have earned a 5c feed-in tariff: about 30c a day in lost export credit.
Swap in your own rates. The sums work the same in any currency.