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Charging your e-car at home

A fueling point in your own home: Most home-owners use a wall-box to supply their e-car with energy. But even if you live in a rental apartment, you can use domestic electricity for charging. We explain how that works and outline opportunities in Germany for state grants to help with this.

Fundamentally, all you need for charging is a socket and a charging cable. But charging an e-car using a conventional household socket is not to be recommended. That’s because it only allows for single-phase charging. Moreover, it can only handle a charging current of 10 amps – and so is only suitable in limited circumstances for continuous charging of electric vehicles. On top of that, emergency charging using a standard domestic “Schuko socket” not only takes significantly longer, but can also cause an imbalance in the power grid. 

 

Charging safely and efficiently using a wall-box

To charge the car safely and efficiently, you need a wall charging unit or wall-box. Private households in Germany are typically connected to the grid using three-phase current, allowing charging devices for an e-car to be installed easily. They can also be coupled with a Smart Home system or photovoltaic system. An electrician connects the wall-box to the three-phase 400-volt domestic supply. Wall-boxes need to be on a dedicated circuit with no ancillary consumer units.

The time the vehicle takes to charge depends on the interplay between the wall-box’s charging capacity and the size of the car’s battery. The European standard for charging using the domestic A/C supply is a Type 2 connector, permitting three-phase charging up to 22 kilowatts (400 volts, 32 amps). If you use a CCS Combo-2 connector, which resembles a Type 2 connector but has an additional two contacts (CCS = “combined charging system”), it enables rapid charging up to 450 kilowatts.  

Three-phase charging using a wall-box does not cause any asymmetries in the power grid, as can occur with single-phase charging. It is grid-compatible[3] and safe. That’s because wall-boxes are protected using circuit-breakers to guard against the charging cable being overloaded, and residual current circuit breakers (ground fault circuit interrupters). The latter are tripped in the event of a defect in the cabling or a damp contact.

Wall-box: Requirements for the domestic power network

It is important to note that wall-box installation is definitely a job for a specialist electrician – who first needs to check the house wiring. If an e-car is being charged, large amounts of electricity flow through the wiring over several hours. For that reason, the wiring and the networks beyond the wall charging unit need to satisfy the requirements appropriate to modern charging technology. In many properties, the electrical installation at the time of building was designed for less power-intensive consumer units. Accordingly, existing installations may sometimes be unsuitable for charging at high power over extended periods – particularly if several e-cars need to be charged simultaneously. A further important requirement is that the charging unit needs to be registered with the grid operator. For 22-kilowatt wall-boxes, the power company must even issue a license before the box goes into use.

To charge your car safely and efficiently, use a wall charging unit or wall-box © BMW
To charge your car safely and efficiently, use a wall charging unit or wall-box © BMW

Charging at home – in a rental apartment or under a joint ownership arrangement

So what do you do if you want to install a wall-box, but you first need to get the landlord or joint owners on board too? At the end of 2020, legislation came into force in Germany to promote electric mobility and to modernize the law governing residential property, amending the regulations governing property registration and costs (Wohnungseigentumsmodernisierungsgesetz, WEMoG). Apartment owners can now request approval for installation of a charging unit, the German motoring association ADAC advises.

Joint owners now only share in the mutual decision as to how the charging unit is to be installed. Those who don’t want to share in the costs of this are not compelled to do so – but then they are not allowed to use the charging-point either. Tenants, too, have a fundamental entitlement to a facility for charging their e-car. However, the tenant himself pays for the charging-point to be installed.

That said, how the electrical installation is configured in the apartment building remains a key issue. The German Association of the Automotive Industry (VDA), together with the German Association of Energy and Water Industries (BDEW) and the Federal Association of German Housing and Real Estate Companies (GdW), advise that many domestic connections in such properties are still only equipped for the standard requirements from the 1980s.

Apartment owners in Germany can now request approval for installation of a charging unit © Opel
Apartment owners in Germany can now request approval for installation of a charging unit © Opel

So what about the financing for this?

Homeowners need to invest sizeable sums to adapt electrical installations to the higher consumption requirements and to install suitable load management. Even though there are funding opportunities available from central government and the German federal states, the associations are calling for a separate funding program for high-performance electrical infrastructures in apartment buildings, and have submitted a proposed concept for this. Their wish is for this subsidy to extend well beyond the purchase of the charging unit, as is currently offered by the reconstruction loan corporation Kreditanstalt für Wiederaufbau (KfW): Home-owners and apartment owner groups, tenants and landlords are able to obtain a EUR 900 grant for each charging unit they install – if the charging units are installed within the purely privately-used footprint of residential buildings and are operated exclusively using green electricity. 

(Stage photo: © Volkswagen AG)

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