With a wallbox, you can charge your electric car quickly and conveniently from home. Combine the wallbox with photovoltaics and use solar power to charge your electric car. This reduces costs and lowers emissions at the same time. You can find out everything about photovoltaics with a wallbox here.
What is a wallbox?
A wallbox, also wall charging station named, is an electrical device for managing the charging of electric cars at home. It is mounted on the wall or a column. Wallboxes securely connect the high-voltage connection to the electric car and ensure fast and safe charging of the battery.
Can I not park an electric car at the Power outlet load?
You can also charge the electric car using a socket. However, the charging process is about 4.5 times slower than using a wallbox and can take several days.
Charging from a household socket is also a security riskNormal sockets are designed for continuous currents of up to ten amps. If this limit is exceeded, the cables and socket contacts can overheat. In the worst case, this can lead to a cable fire.
How does a wallbox work in conjunction with a PV system?
Simply explained, the PV system generates Electricity from sunlight and uses this to charge the electric car. The wallbox only needs the PV surplus for charging. The electricity needs in the household are covered first and charging the PV storage unit also has priority. If the PV system produces excess electricity, the electric car is charged via the wallbox.
How a PV system works with a wallbox
In order to charge your electric car with solar power, the wallbox and the PV system must communicate with each other. For this, you need an energy manager that is either integrated in the inverter or in a smart meter. It calculates the maximum charging capacity of the station based on the electricity production and household electricity consumption. This tries to avoid drawing power from the grid as much as possible.
How long does the charging process at a wallbox take?
The charging time of a vehicle depends on the battery capacity, the maximum charging power and the performance of the charger. It varies from vehicle to vehicle. A small car with a capacity of 22 kW is charged in less than three hours. Fast charging takes 20 to 40 minutes. Due to the decreasing performance and the higher time required, users often stop charging at 80%. Depending on the vehicle and station, a range of 100 km is possible in 10 minutes of charging time.
What do I need to pay attention to when connecting to the power supply?
To charge an electric car you need a 400 volt three-phase connection. You will therefore need to install a powerful power cable to connect the wallbox:
- For a charging power of 11 kW you need a 16 amp fuse;
- For a charging power of 22 kW you need a 32 amp fuse.
What options are there for PV surplus charging?
To charge with PV surplus, you need intelligent charging and energy management. Below we show you the options for PV surplus charging.
Rigid control
One option is to enable the charging station via a switching contact on the inverter. This option is available on many inverters and charging stations. The inverter is set so that the charging station is activated when it reaches a certain power or a defined yield.
The rigid control is the most cost-effective option and enables continuous use - without additional costs for storage. However, it does not take into account the household's current electricity consumption or needs. In addition, there is no continuous charging current control, which prevents charging when PV yield is low. The use of additional charging current from the power grid is necessary as a compromise solution.
There is a potential problem that, in case of doubt, the electric vehicle will not be charged at all. In order for the electric vehicle to reach a certain charge level at a certain time, you must adjust the operating mode of the charging station accordingly.
Dynamic Control
With dynamic control, the charging station adjusts its power value based on the energy surplus of the PV system. Self-consumption in the household is prioritized and the charge controller adjusts the power accordingly. Since you usually need grid power to charge the electric vehicle, the system allows you to configure the permissible grid power requirement. For example, the charging process can start with 80 percent grid power and 20 percent PV power. If the PV surplus increases, the feed-in to the grid is automatically reduced.
Here, too, there is the possibility that the electric car is not sufficiently charged or is not charging at all. This is because the wallbox only starts charging once the specified amount of solar power is available. The operation of the charging station should therefore be adjusted so that charging is only possible when the power is drawn from the grid.
Weather-dependent charging
Manufacturers offer solutions for obtaining data from weather forecast systems via the Internet. You can program the management system to determine how much PV surplus the electric vehicle should use and for how many hours. The program calculates whether the predicted PV yield is sufficient. Otherwise, it charges with additional grid power and ensures that the electric vehicle is fully charged within the specified period. This means you do not run the risk of your electric car not being charged.
Can I combine the wallbox with a PV storage system?
You can combine the wallbox with a PV storage unit. This means you can even charge your electric car using solar power alone. The power storage unit charges with PV surplus during the day and allows you to charge your car at any time. Without a storage unit, you have to charge the car when the PV system produces excess electricity.
How much does a wallbox for photovoltaics cost?
A wallbox for photovoltaics costs €1,000 to €3,500, depending on the model and technical requirements. For the PV system, expect to pay €1,200 to €1,600 per kWp of installed power. If you add a PV storage system, the costs increase by around €1,000 per kWh of storage capacity.
How much does it cost to install and assemble a wallbox?
The costs for installing and connecting a wallbox to the power grid range between €1,000 and €5,200. The prices for individual items such as adapting the electrical box, electrical work and laying cables range between €0 and €899, €65 and €883 and €196 and €821 respectively.
Can I have a Installing the Wallbox yourself and save costs?
The wallbox must be installed by a specialist company. This company ensures safety and proper registration with the network operator. Laypeople risk electric shocks, fires or damage to the house when installing it themselves.
How much can I save with photovoltaics and wallbox?
With photovoltaics and a wallbox, you save at least 20 cents per kilowatt hour compared to charging from the grid. While the electricity generation costs for PV are 5 to 11 cents/kWh, a kWh of electricity costs 30 to 40 cents. How much you actually save depends primarily on your driving style and electricity consumption.
Hereinafter Example we compare the fuel costs of an electric car with a diesel and a petrol car.
| mileage | cost of diesel cars | cost of a gasoline car | Costs of electric cars with grid connection | Costs of electric cars with photovoltaics |
| 10,000 km per year | 1.393 € | 1.351 € | 720 € | 220 € |
| 15,000 km per year | 2.089 € | 2.026 € | 1.080 € | 330 € |
| 20,000 km per year | 2.798 € | 2.702 € | 1.440 € | 440 € |
Is there any funding?
There is no special funding for a wallbox with photovoltaics. However, some cities and municipalities offer funding for electromobility and renewable energies. You can apply for additional funding for photovoltaics from the Kreditanstalt für Wiederaufbau (KfW) using loan 270.
For a short period of time (September 2023), KfW subsidized the wallbox in combination with a solar system and solar storage through grant 442. The electric car had to already be available or ordered. The maximum subsidy rate was €10,200. The subsidies were exhausted within 24 hours.
Do I have to register the wallbox?
You must have wallboxes over 4.7 kW to the grid operator. Systems over 12 kVA even require a commissioning permit from the grid operator. The reporting and notification obligations are specified in the Renewable Energy Sources Act (EEG), the Grid Connection Ordinance (NAV), the Charging Station Ordinance (LSV) and the Technical Connection Rules (TAR).
How much photovoltaics do I need for a wallbox?
A wallbox requires around 2 kWp of nominal power per 10,000 kilometers of driving per year. Exactly how much PV power you need depends on the electric car and the annual mileage.
| km per year | electricity consumption | PV system performance Wallbox | required roof area | PV system performance wallbox and single-family home | required roof area |
| 10,000 km | 2,000 kWh | 2 kWp | 10.2 m² | 8 kWp | 40.8 m² |
| 15,000 km | 3,000 kWh | 3 kWp | 15.3 m² | 9 kWp | 45.9 m² |
| 20,000 km | 4,000 kWh | 4 kWp | 20.4 m² | 10 kWp | 51 m² |
| 25,000 km | 5,000 kWh | 5 kWp | 25.5 m² | 11 kWp | 56.1 m² |
Which wallboxes are the best (test)?
The ADAC tested eight wallboxes and the Fronius Wattpilot Home 11 J 2.0 was crowned the test winner. Second place went to the Entratek Power Dot Fix and third place went to the KEBA KeContact P30 PV Edition.
The following parameter compared:
- Scope of delivery and assembly
- Security
- function
- equipment
- app
What are the advantages and disadvantages of a wallbox?
A wallbox in combination with a photovoltaic system has many advantages and only one small disadvantage. You need a 400 volt three-phase connection and have to hire an electrician to do it. In return, you reduce your electricity costs and at the same time reduce CO₂ emissions.
Let’s take a closer look at each of the benefits.
Increased self-consumption
By charging the electric car with PV surplus, you increase your own consumption. With a normal PV system, you only achieve a self-consumption share of around 30%. With a wallbox, the share increases to up to 60%.
This is particularly advantageous as electricity prices are currently very high and the feed-in tariff is getting lower and lower. This means that selling solar power is no longer worthwhile, but using it yourself is even more worthwhile. The higher the self-consumption, the higher the return on a PV system.
cost savings
You save at least 20 cents per kilowatt hour of solar power that you use to charge your electric car. Despite the high initial costs, the electricity generation costs for photovoltaics are only 5 to 11 cents per kilowatt hour. You pay 30 to 40 cents for one kilowatt hour of power drawn from the grid. And since a PV system has a lifespan of over 30 years, you reduce your electricity costs in the long term.
environmental protection
When you charge your electric car with mains power, you only use renewable energy. Charging with photovoltaics is based 100 percent on renewable energy and is completely emission-free.
safety and convenience
With a wallbox, you can charge your car at home and no longer have to drive to a charging station. The charging process is safer and more convenient. You just have to connect the electric car to the wallbox and you don't have to worry about someone pulling the charging plug out of your car.
