EV charger: 11 kW or 22 kW?What your car charges.

For an electric car in a single-family home, we recommend an 11 kW wallbox in most cases. A 22 kW wallbox only charges twice as fast if the car can also accept 22 kW of alternating current. Many cars cannot. In that case you pay for power that goes unused.

This page shows how to work out the right power for your car and your house. We plan the EV charger with you at the free site visit.

What the number on the wallbox means

The power in kW tells you how much electricity can flow per hour. It follows from voltage, current and number of phases:

Power	Connection	Guide range per hour
3.7 kW	single-phase, 16 A	about 20 km
7.4 kW	single-phase, 32 A	about 40 km
11 kW	three-phase, 16 A	about 60 to 70 km
22 kW	three-phase, 32 A	about 120 to 130 km, only if the car can do it

The ranges are guide values at a consumption of about 18 kWh per 100 km. In winter and on motorways consumption is higher, so the range per hour of charging is lower.

Step 1: What your car accepts on AC

At home you charge with alternating current (AC). Inside the car the onboard charger converts it to direct current, and this onboard charger sets the upper limit. For many current models it is 11 kW, for some 7.4 kW or less, for a few 22 kW. A 22 kW wallbox then still charges only at the power the car allows. CKW gives an example: a VW ID.4 Pure limits itself to 11 kW at a 22 kW charging station.

You find the figure in your car’s data sheet under «AC charging» or «onboard charger». If you have not bought the car yet, it is worth looking before you order the wallbox. If you change cars in a few years, the value may be higher or lower. For that we plan a cable with some reserve. A stronger wallbox is rarely needed for it.

Fast charging at 50 kW and more is direct current and takes place at public fast-charging stations. It is not a topic for home.

Step 2: How much you really charge

What matters is the amount of energy per day. An example with the assumptions we use on other pages:

• Mileage 15,000 km a year
• Consumption 18 kWh per 100 km
• Annual demand: 15,000 km times 0.18 kWh = 2,700 kWh, on average a little over 7 kWh per day

At 3.7 kW you charge this amount in just under 2 hours, at 11 kW in about 40 minutes. At night the car usually stands at the wallbox for eight hours or more. Even if you drive 150 kilometres in a day and recharge about 27 kWh, you are done in two and a half hours at 11 kW.

Higher power can make sense in these cases:

• The car is only parked briefly, for example between two shifts.
• Several people share one charger and take turns.
• The car has a very large battery and is driven almost empty every day.

Step 1 applies here too: the power only helps if the car accepts it.

Step 3: Cable and house connection

A 22 kW wallbox needs a cable for 32 amperes per phase and correspondingly strong fusing in the distribution board. That means thicker cables and a higher load on the house connection. In older houses, or where a heat pump, oven and hot water share the same connection, the house connection can set the limit.

At the site visit we check:

• Size and condition of the distribution board
• Capacity of the house connection and load from other appliances
• Length and route of the cable to the parking space
• Reserve for a second car

Load management can help. It lowers the charging power automatically when the heat pump or cooker draws a lot of electricity. A smaller cable is then sufficient. With a heat pump and a solar system it is worth planning wallbox and heating together.

The total cost of an EV charger is around CHF 2,000 to 5,500. The cable route has the greatest influence, the power level matters less. A breakdown is in the guide What does an EV charger cost?.

Step 4: Registration with the grid operator

Every fixed EV charger must be reported to the grid operator. The electrical installer does this, usually with a technical connection request and an installation notice. After installation the safety certificate follows.

Where the grid operator draws the line differs. At the grid operator CKW, for example, registration is enough up to 11 kW, and above 11 kW approval is needed before installation (source: CKW, legal requirements for EV chargers, German). Other utilities set the limit differently. At 22 kW you should therefore expect an approval and a longer lead time.

We register your installation and clarify your grid operator’s requirements before the quote. In apartment buildings and condominium ownership, consent from property management or the owners’ association is also needed. More under EV charging in underground car parks.

11 kW or 22 kW: a decision aid

Situation	Recommendation
Single-family home, one car, parked overnight	11 kW
Car with onboard charger below 11 kW	11 kW, with long parking times less is enough
Car with 22 kW onboard charger, little parking time	consider 22 kW, with approval
Two cars on the same house connection	11 kW with load management
Company car park with changing vehicles	load management and multi-charger solution

A single-phase connection with 3.7 or 7.4 kW is enough if the car is parked for long periods and drives little. It is cheaper and puts less load on the house connection. Because of the smaller reserve, we only recommend it if future cars will need little more.

Working with the solar system

If you want to charge the car with your own solar power, you need a wallbox that adjusts its power to the surplus. The rated power is then secondary, because a roof rarely delivers more than 5 to 8 kW during the day. How surplus charging works is explained in the guide EV charger with a solar system. With a solar system and a home battery, a larger share of your driving electricity can come from your own roof.

We calculate it for your house

At the free site visit we check the distribution board, house connection, cable route and your car’s data sheet. After that you know whether 11 kW is enough or whether more power pays off. Within 72 hours you receive a binding quote. We handle registration with the grid operator, installation by our own installers and commissioning from a single source, from Zumikon and Lachen for the whole of German-speaking Switzerland.