Electromobility at Mobility
Bidirectional charging: the future of e-mobility explained in simple terms
26.06.2024
Imagine your electric car not only consuming electricity, but also acting as a mobile energy source. That’s exactly what bidirectional charging facilitates – a technology with great potential. Read on to find out how it works, where it could be used, and what the challenges are.
Key points at a glance:
Definition: Bidirectional charging enables electric cars not only to recharge their batteries, but also to serve as a mobile energy source.
Possible applications: There are various possible uses. For example, using the electricity stored in the electric car battery for the home grid or feeding energy back into the general grid to cushion peak loads.
Challenges Compatibility between direct current (electric cars) and alternating current (power grid). The need for specialised charging stations and suitable electric vehicles.
Current status: The legal framework in Switzerland is still unclear, but there are positive developments thanks to new legal amendments and promising results from pilot projects.
The term sounds a bit clunky, but the idea behind it is ingenious: “Bidirectional charging” describes the ability of an electric vehicle not only to recharge its batteries, but also to surplus/unused Energy also to save and then into an electricity grid. The technology might already be advanced in other countries, but in Switzerland, bidirectional charging is still in its infancy. In the following five points, you will find out what bidirectional charging is all about – and what hurdles there are still in Switzerland in this regard.
1. What is bidirectional charging?
With bidirectional charging, the electric car battery temporarily becomes an energy storage device. The stored current can thus be stored later, e.g. B. used in the household or fed into the power grid.
An electric car can therefore not only be charged with electricity, but also output electricity. One of the greatest challenges facing renewable energies is the issue of storage. When the sun shines on a rooftop photovoltaic array, the electricity produced isn’t always needed immediately.
To stop the energy being wasted, it needs to be stored somewhere until it is. This can be achieved with dedicated batteries, but they aren’t cheap. However, there’s often an effective alternative right there on the doorstep: the electric car. Given the right technology, the electric car can be used as a mobile powerbank.
While the technology is already well advanced in other countries, it is still in its infancy in Switzerland. Our article “Is Switzerland ready for bidirectional charging?“ gives you a Overview of the situation in Switzerland.
2. Where is bidirectional charging used?
There are several ways in which bidirectionally charging e-cars can be used in practice:
Vehicle-to-Home (V2H): bidirectional charging enables the electricity stored in the car to supply the house where you live. Here, having previously been supplied with electricity by the home’s PV system when the sun was shining, it’s the electric car’s turn to power the home. All part of a virtuous cycle.
Vehicle-to-Grid (V2G): it’s also possible to feed the energy in the car back into the grid. In this way, current peaks could be smoothed. If the electric car is charged at off-peak times, the stored energy can be fed into the grid at peak times to relieve the grid.
Vehicle-to-Building (V2B): The electricity stored in the car can also be used to supply a building. The electric car can power office buildings, schools or other commercial buildings, helping to reduce energy costs and maximize the use of renewable energy.
Vehicle-to-everything (V2X): This technology makes it possible to share the electricity stored in an electric car with various end devices and infrastructures. This includes not only households and the power grid, but also other vehicles, appliances and public facilities. V2X stands for the comprehensive networking and use of energy sources to improve the efficiency and stability of the entire energy system.
Vehicle-to-load (V2 L): Bidirectional charging makes it possible to use the electricity stored in the car to power electrical devices and machines directly. The electric car acts as a mobile power source for tools, household appliances or camping equipment.
Another argument in favour of bidirectional charging is the fact that private cars can charge up to 23 hours a day standing around unused. It is precisely at this time that they could feed electricity back into the grid. All that is required is to register the bidirectional charging station with the local network operator as a “simple” charging station.
3. Why isn’t bidirectional charging available everywhere yet?
Although “powerbanks on wheels” technology is promising, a few hurdles remain to be overcome.
Conversion: Electric vehicles usually run on direct current, while our power grid runs on alternating current. Most e-car models are equipped with an on-board charger that converts alternating current into direct current – but only in one direction.
Suitable wallbox: To allow the electricity to flow in the opposite direction as well, specially designed charge points and plugs are required. These are beginning to be available in Switzerland, but overall there’s a lot of catching up to do.
Vehicle compatibility: Not all electric vehicles on the market are yet suitable for bidirectional charging. However, this will change quickly. Japan, for instance, has long made it mandatory for electric vehicle to be equipped with bidirectional charging technology.
Standards and protocols: There are still different standards and protocols for bidirectional charging. This can lead to incompatibilities between the electric vehicle and the charging station. Some manufacturers use their own systems, which makes interoperability more difficult and limits the selection of suitable charging stations.
Costs for bidirectional wall boxes: The cost of a charging station is much higher if it can also charge bidirectionally. The additional features and technical requirements of bidirectional charging significantly increase acquisition costs, which is a hurdle for many users.
Intelligent load management: Bidirectional charging requires intelligent load management to optimize charging and unloading. This means that energy flows must be monitored and controlled in real time to ensure efficient use of resources. Such systems are complex and require additional investments in hardware and software to ensure smooth and efficient operation.
What is “V2X Suisse” all about? (The video was published at the start of the project in autumn 2022)
4. What about the legal and political dimensions?
The legal framework is also unclear. There is no law in Switzerland that prohibits bidirectional charging. Rather, it is equated with the stationary battery operation mentioned at the outset.
Things get more complex when it comes to Integration of the electric car into the general electricity grid. To ensure that this is feasible not only technically but also economically, amendments to the Electricity Act are necessary at the national level. An important step in this direction is the result of the referendum held on 9 June 2024 to the Federal Act on a Secure Electricity Supply with Renewable Energies. Thanks to the positive decision of the Swiss electorate, it is now possible to create local alliances beyond the individual building, or PCA for short in technical jargon. Although the primary legislation put to the vote does not explicitly mention e-mobility, it definitely opens the way for the technology.
5. What’s Mobility doing to promote the new charging technology?
The potential of bidirectional charging is obvious – especially so far as Mobility is concerned. By 2030, all of our 3,000 vehicles will be electrically powered. However, electromobility increases the demand for electricity and poses challenges in terms of grid stability. This is where bidirectional charging could turn out to be a trump card. Together, such a fleet of vehicles can virtual power plant which, if necessary, can help stabilise the power grid.
That’s why Mobility recently launched its two-year Pilot project for bidirectional charging successfully completed. Between September 2022 and March 2024, 50 Honda e all-electric cars were available at 40 Mobility stations dotted around Switzerland. Among other things, electricity from the vehicles was offered to three different customers. The results of the trial are currently being analysed. One thing is already clear, though: the technology works – but there’s still a lot of work to be done in Switzerland before it can be used on a widespread basis.
FAQ
- Is bidirectional charging allowed in Switzerland?
- How far has bidirectional charging technology come?
- Does bidirectional charging damage the vehicle battery?
- What are the benefits of bidirectional charging?