Charging an electric car with solar-powered electricity: How do I save money?
In light of feed-in tariffs declining and electricity costs rising, self-consumption of photovoltaic electricity is becoming increasingly important. Instead of feeding the electricity you’ve produced yourself into the grid for a low profit*, you should consume or temporarily store as much electricity as possible yourself.
The savings for each self-consumed kilowatt hour today is up to 26 ct., since you don’t have to purchase expensive electricity from the grid (electricity costs: up to 33 ct/kWh) or store your self-produced PV electricity temporarily in the power grid at high cost.
Flexible consumers play an important role in being able to use as much of your self-generated electricity as possible.
An electric car is particularly well suited to this purpose, since an electric vehicle is usually stationary for far longer (22 hours per day on average) than it is charging. This means your electric vehicle can be flexibly charged at a time that suits you, helping to ensure that as much of the PV electricity you generate yourself can be used.
* The feed-in tariff in Germany for new installations in July 2022 is 6.23 ct/kWh for installations generating up to 10 kWp, 6.06 ct/kWh for installations generating up to 40 kWp and 4.74 ct/kWh for installations generating up to 100 kWp.
Solar installation for charging your electric car: What are the advantages?
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.
Cutting costs
Self-generated PV electricity gets your electric car moving at a cheap rate. You save 26 ct/kWh in costs compared to drawing electricity from the grid.
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.*
* www.fraunhofer.de
Charging an electric car with solar-powered electricity: What do I need for that?
If you’d like to efficiently charge your electric car from your solar installation, you need a system consisting of three components.
Additional meter
- Installed behind the ESC meter; measures the surplus electricity.
- Passes this data on to the smart control system.
Smart control system
- Processes this data; uses the data to create the charging strategy. Also considers other factors (departure time, desired state of charge, etc.)
- Passes the charging strategy on to the charging station.
Charging station
Implements the smart control system’s charging strategy and communicates with the vehicle.
Your system doesn’t necessarily have to comprise three separate pieces of hardware. Some charging stations already have the smart control system integrated, enabling them to create their very own charging strategies. If your charging station does not have a smart control system, you can use a solar manager (also known as an “energy manager”). It processes the data from the auxiliary meter and develops the strategies for several consumers.
The schematic diagram below shows the PV installation’s potential consumers. In addition to the charging station, the home and electricity storage device can also be connected to the solar-powered electricity. In the future, the electric car will even be able to replace the domestic electricity storage device shown here. This technology is known as Vehicle-to-Home (V2H).
Supplying your electric car and private household with solar-powered electricity
Charging solutions for charging with solar-powered electricity
To find the right charging solution for charging with solar-powered electricity, it’s helpful to figure out which of the above items you already have, and which ones you still need. If you already have individual components at your disposal, you must take special care to ensure that new individual parts are compatible with your existing system.
Looking for a charging station that’s compatible with your existing system?
We have individual components that will complement your system perfectly.
You can find an overview of the individual systems’ compatibility here. Excel auf EN?
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KEBA KeContact P30 c-series GREEN EDITION 122.108 charging stationSpecial Price €1,199.00 Regular Price €1,269.00 -
FAQs: The key questions about charging with solar-powered electricity
Do I have enough solar-powered electricity to charge my electric car?
Generally speaking, an electric car is sitting idle for a very long time when it’s parked at home. The amount of energy required to cover the daily driving distance is very small in comparison. This gives you the flexibility to charge either at a lower charging power and/or at certain times, depending on the solar surplus. So you can still charge your electric vehicle with some PV electricity when you’re out during the day and come back from work in the afternoon. The average daily mileage is 50 km. With a charging power of 4.2 kW, you could recharge this required range in less than two hours.
What is the difference between single-phase and three-phase charging?
A vehicle needs at least 6 amps (A) per phase to start charging. Some vehicles even need 10 A. This translates into a minimum charging power of 1.4 kW for single-phase charging and 4.2 kW for three-phase charging. Charging stations generally have a three-phase connection. This means the charging process would only start at a surplus of 4.2 kW.
Some PV charging solutions can therefore switch between single-phase and three-phase charging with a view to charging even with a smaller PV surplus. In fact, for private individuals, the majority of charging takes place with 100% PV electricity in the single-phase range.
Explanation of the figures below: The figure on the left shows a charging solution without any phase changeover. In this situation, you would only charge the current proportion of electricity marked in light blue. The figure on the right describes a charging solution with phase changeover. Here, the proportion of electricity marked in dark blue could be available for charging too.
Image source: SMA - Abbildungen auf EN?
What are the charging strategies for charging with solar-powered electricity?
An ideal PV charging solution should offer the following three charging strategies outlined below as a bare minimum.
PV surplus only
- Charging with 100% PV electricity
- Starting and stopping the charging process depending on the PV surplus
- Charging power depending on the PV surplus
Electricity mix
- Additional decision variable
- Specified amount of energy
- Specified distance
- Dynamic electricity tariff
- Prioritized PV electricity charging, adding electricity drawn from the grid if necessary.
Maximum power
- Charging with maximum possible power, regardless of where the electricity has come from.
- In case a lot of power is needed fast.
Can I charge my electric car with a balcony power plant?
In principle, balcony power plants are unsuitable for charging an electric car. In Germany, balcony power plants offer 600 W maximum power at present. For many electric cars, this does not achieve the minimum power required to start the charging process. So it doesn’t make sense to use a balcony power plant to charge an electric car.