Charge electric car intelligently with PV surplus & save money

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    KEBA KeContact P30 PV Set Advanced 127.816 (11 kW, incl. 6m type 2 cable, integrated energy meter, LAN/Wi-Fi, OCPP/UDP/Modbus TCP, DC protection)
    €1,429.00
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  2. The Mobility House | KEBA KeContact P30 PV Set Advanced 127.814
    KEBA KeContact P30 PV Set Advanced 127.814 (22 kW, socket type 2, integrated energy meter, LAN/Wi-Fi, OCPP/UDP/Modbus TCP, DC protection)
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  3. The Mobility House | KEBA KeContact P30 PV Set Professional 127.818
    KEBA KeContact P30 PV Set Professional 127.818 (11 kW, incl. 6m type 2 cable, RFID, MID, LAN/Wi-Fi, OCPP/UDP/Modbus TCP, DC protection)
    €1,489.00
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  4. The Mobility House | SMARTFOX PRO 2 Solar-Energiemanagementsystem
    SMARTFOX PRO Solar Energy Management System (incl. 80A current transformer)
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    SMARTFOX PRO Solar Energy Management System (incl. 100A current transformer)
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    The Mobility House | ABL Energy Management System EMSHOME
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  7. The Mobility House I Lizenz Smartfox Car Charger
    Lizenz Smartfox Car Charger
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  8. SMARTFOX contactor for charging station 1ph/3ph change-over (40A)
    SMARTFOX contactor for charging station 1ph/3ph change-over (40A)
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Three ways of charging your electric car with self-produced electricity and saving money

  • You charge regardless of how much solar-powered electricity your PV installation is producing.
  • You can therefore draw an average of 15 % of your charged electricity from your own roof and save around € 80 per year*. 
  • You charge mainly when your PV installation produces a great deal of surplus electricity.
  • You are therefore increasing the proportion of self-produced electricity used during charging to an average of 56 % and are saving around € 300 per year*. 
  • You charge your electric car when there is an adequate PV surplus or when there is sufficient electricity available in the storage system for the electric car.
  • You are therefore increasing your personal proportion to up to 99 % and saving approx. € 480 per year*.

Find out in detail below how high your savings potential could be depending on the charging scenario and which charging solution is the right one for you. 

* Assumption: You pay 32.80 cents per kilowatt hour to your grid operator. You yourself receive 6.23 cents per kilowatt hour fed into the grid as remuneration.

Three advantages of charging your electric car with solar-powered electricity

Icon: Increase self consumption Icon: Increase self consumption

Increasing PV self-consumption

In light of feed-in tariffs decreasing and electricity prices increasing, it is no longer economical to purely sell PV electricity. You should therefore use or temporarily store as much electricity as possible yourself.

Icon: Save costs Icon: Save costs

Saving electricity costs

Self-generated PV electricity gets your electric car moving at a cheap rate. You save up to 26 cents per kilowatt hour*. The more electricity prices rise, the more it pays off for you.

Icon: Protect environment Icon: Protect environment

Protecting the environment

When you use electricity generated from renewable energy sources, greenhouse gas emissions can be reduced by up to 70 % over an electric vehicle’s total useful life.**

Making the most of your solar-powered electricity to charge your electric car

There are three scenarios with different charging solutions which you can use to charge your electric car with solar-powered electricity drawn from your PV installation. Use our examples to calculate which charging solution is most cost-effective for you.

1. Uncontrolled charging without electricity storage and using 15 % self-produced electricity

What does uncontrolled charging mean? How does it work? How much can I save? What is the right charging solution for me in this case? 

Imagine the following situation: You come home, plug in your electric car, and the charging process starts immediately. Regardless of how much solar-powered electricity you are currently producing yourself. That’s uncontrolled charging.

Your electric car draws the additional power it needs directly from the grid. H. Martin, a PhD candidate at ETH Zurich, found in a study that you only use 15 % of the charged electricity from your own PV installation on average. Provided that you drive your electric car during the day and charge it mainly after work or your day trip.

Save up to € 80 per year with uncontrolled charging

Let’s assume the following for our sample calculation:

On average, your electric car consumes about 20 kWh per 100 kilometers. Charging losses are included here. You drive 10,000 kilometers per year in total. This results in an average consumption of 2,000 kWh per year for your electric car.

Let’s further assume:

  • You pay 32.80 cents per kilowatt hour to your grid operator.
  • You yourself receive 6.23 cents per kilowatt hour fed into the grid as remuneration.

Scenario 1 results in the following cost breakdown for the charged electricity:

  • Costs for 85 % electricity drawn from the grid: 1,700 kWh x 32.80 ct. = 557.60 
  • Costs for 15 % electricity drawn from the PV installation: 300 kWh x 6.23 ct. = 18.69 
  • Total costs for electricity mix comprising 85 % electricity drawn from the grid and 15 % PV electricity: 576.29 
  • For comparison: Costs for 100 % electricity drwan from the grid: 2,000 kWh x 32.80 ct. = € 656 

The average savings potential in this case is 79.71 per year.

Result: You could use any wallbox – you’re free to choose the one that suits you

15 % personal proportion are enough for you? Then you’re free to choose from our range of wallboxes or mobile charging stations. Any of our charging solutions is suitable for you.

Our tip: We recently conducted a survey. And, from it, we found out the following: 87% of respondents who opted for this scenario would buy a smart charging station now. For the remaining 13% of respondents, they are in the habit of controlling the charging process manually and charging whenever the sun is shining in the sky.

2. Controlled charging without electricity storage and using 56 % self-produced electricity

Now let’s look at scenario 2. In his study, H. Martin also found that drivers of electric cars who charge their cars with a smart charging solution can draw up to 56 % of the charged electricity from their own photovoltaic installation. You can even increase the percentage if you have the opportunity to charge your electric car during the day too.

This means: Controlled charging (smart charging) enables you to charge your electric car mainly when there is a correspondingly large PV surplus available. The system automatically adjusts the charging power depending on the surplus. Only when the electric car is to reach a certain state of charge does your electric car draw additional power from the grid.

Save up to € 300 per year with smart charging

Scenario 2 results in the following cost breakdown for the charged electricity:

  • Costs for 44 % electricity drawn from the grid: 880 kWh x 32.80 ct. = 288.64 
  • Costs for 56 % electricity drawn from the PV installation: 1,120 kWh x 6.23 ct. = 69.78 
  • Total costs for electricity mix comprising 44 % electricity drawn from the grid and 56 % PV electricity: 358.42 
  • For comparison: Costs for 100 % electricity drawn from the grid: 2,000 kWh x 32.80 ct. = € 656 

The average savings potential in this case is 297.58 per year.

Result: A holistic energy management system 

You can use the holistic energy management system to optimize your entire electricity consumption at home. The charging station and the electric car are integrated as additional consumers here. 

Do you already have an energy management system and all you need is the right wallbox? Then we recommend e.g. the KEBA c-Series. It is compatible with a wide range of energy management systems.

If you still need an energy management system for self-consumption optimization and to control your charging station, we recommend the Smartfox Pro Solar. While the initial costs might seem high at first, they will have amortized after less than three years. The amortization date may occur earlier as electricity costs rise.

3. Controlled charging with electricity storage and using up to 99 % self-produced electricity


According to the study conducted by ETH Zurich, with a storage solution on average you can use more than 90 % and up to 99 % of the electricity from your solar installation to charge your electric car. However, you experience higher charging losses here because the electricity is temporarily stored in the storage device first of all before it then flows back into your electric car. 

Save up to € 480 per year with smart charging and an energy storage

Scenario 3 results in the following cost breakdown for the charged electricity:

  • Costs for 10 % electricity drawn from the grid: 200 kWh x 32.80 ct. = 65.60 
  • Costs for 90 % drawn from the PV installation: 1,800 kWh x 6.23 ct. = 112.14
  • Total costs for electricity mix comprising 10 % electricity drawn from the grid and 90 % PV electricity: 177.74
  • For comparison: Costs for 100 % electricity drawn from the grid: 2,000 kWh x 32.80 ct. = 656 

The average savings potential in this case is 478.26 per year.

Due to the high energy loss and the additional costs for storage, we advise against using this solution and recommend scenario 2 instead (controlled charging without energy storage). 

Result: A holistic energy management system

For scenario 3, you can use the holistic energy management system from Smartfox mentioned in scenario 2.

Are you looking for individual consultation? We would be happy to support you.

Find out more details on our knowledge center page, including how much solar-powered electricity you can use during single-phase and three-phase charging, and what that means for you. 

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