V2X

Electric cars are turning into power banks and relieve the burden on the electricity supply – our next big step towards greater sustainability. All you need to know about the unique test involving 50 Mobility cars.

A problem becomes a solution – with V2X

One thing is clear: we need to live more sustainably – all of us – if we want to keep global warming as low as possible. Which is why we are moving to 100% e-mobility. By 2030 at the latest, our entire fleet of around 3’000 vehicles will be electric. While increasing e-mobility is a positive trend, it also brings with it higher electricity demand and challenges for network stability. Blackouts could become more likely even in the next few years, particularly in the winter months. The V2X Suisse project is looking to find solutions to this by pooling resources.

Cars with real power

The basic idea behind bidirectional charging is that electric cars not only use electricity, but can also return it to the grid when they aren’t being driven. A private car normally sits idle for an average of 23 hours per day. But these stationary vehicles can actually become mobile power banks that can be connected to a large energy storage device, a bit like a reservoir. So essentially, households can draw power from their electric cars during peak hours, and then recharge them to full overnight at a cheaper rate. A single 11 kilowatt car can supply more electricity in one hour than an average Swiss household uses in a day.

What is “V2X Suisse”?

The research project ran from autumn 2022 to spring 2024. It involved the integration of 50 fully electric bidirectional Honda model ‘e’ cars into Mobility’s regular car-sharing scheme. It was the first large-scale trial featuring bidirectional charging e-cars to be held in Switzerland. The idea was to explore how this technology can be used to reduce load peaks in the power grid and how households with solar installations can optimise their own consumption. In addition, the aim was to investigate the economic potential of bidirectional vehicles in Switzerland and test the competition between potential flexibility consumers on three grid levels (Swissgrid, distribution grid operator and ZEV – association of electricity producers and consumers).

to the final report (in German)

Conclusion: the project has demonstrated the technical feasibility of bidirectional charging and given the technology a boost. It has confirmed that V2H (vehicle-to-home – a proven methodology), and V2G (vehicle-to-grid) work technically, at both the grid level and in terms of benefiting the system as a whole. Such a scheme cannot yet be operated economically by a car sharing company, however.

The following companies were involved in the project in addition to Mobility: Car manufacturer Honda, software developer sun2wheel, charge point developer EVTEC, aggregators tiko, scientific support by novatlantis, in collaboration with ETH. The project is supported under the Swiss Federal Office of Energy’s pilot and demonstration programme.

Terms

Electric vehicles capable of bidirectional charging can not only store electrical energy for driving purposes, but also feed it back into the home. Vehicle-to-home enables you to supply your own home with the stored electrical energy from an electric car. The entire charging and recovery process takes place behind the house’s electricity meter and is often used to increase the self-supply rate for homes via photovoltaic systems.

As with vehicle-to-home, electric vehicles capable of bidirectional charging can not only store electrical energy for driving purposes, but also feed it back into a building with multiple consumers. Vehicle-to-building can be used to supply an apartment block or commercial/industrial units with the stored electrical energy from an electric car, often as part of an electric car fleet. Peak shaving can also help to mitigate usage peaks within the building. The entire charging and recovery process takes place behind the building's connection to the grid.

Electric vehicles capable of bidirectional charging can not only draw electrical energy from the grid, but also feed it back in as part of an intelligent energy system. This process is managed using signals from the distribution or transmission network operator and can take place both at public charging stations and within buildings via the grid connection. V2G charging and discharging of a larger number of electric vehicles (pooling) count as services in energy trading and for stabilisation within both the distribution and transmission networks. Vehicle-to-grid thereby enables intelligent sector coupling.

V2X is used as an umbrella term for all of the above applications, as well as the combined application of multiple types. For example, electric vehicles capable of bidirectional charging parked in a large property’s car park can be used both for self-consumption optimisation and peak shaving purposes (V2B), as well as to serve the grid (V2G). The autonomous supply of individual consumers and island grids, and the charging of other electric vehicles, completes the spectrum.

FAQs

There are a few manufacturers in Switzerland and internationally that have brought technologically mature bidirectional charging stations with CHAdeMO connectors to the market. These have been extensively tested in multi-year trials. Bidirectional charging via CCS connectors has currently only been achieved by one Swiss manufacturer. In Japan, however, bidirectional charging technology has been mandatory for every electric vehicle for a number of years.

Essentially, bidirectional charging is equivalent to operating stationary batteries. If the charging infrastructure complies with the Association of Swiss Electricity Companies’ recommendation on grid connection for energy generation devices (NA-EEA) and the technical standards for electrical safety and electromagnetic compatibility, it qualifies for registration with the distribution network operator. Since 1 January 2022, bidirectional charging stations can be registered as standard using the updated technical connection application (TAG).

Unfortunately not yet. All Japanese electric vehicles are essentially capable of bidirectional charging as it is mandated by the state there. Bidirectional charging is mainly possible with cars with CHAdeMO chargers, although it is also possible with a CCS quick charge cable in one case. Generally, bidirectional charging requires approval of the vehicle manufacturer and certification of the charging station for the vehicle type concerned.

Plug-in vehicles capable of bidirectional charging and available in Switzerland (as of August 2021):

Vehicle	Connector
Nissan Leaf, e-NV-200 (delivery van) and EVALIA (people carrier)	CHAdeMO
Mitsubishi i-MiEV, Outlander und Eclipse Cross	CHAdeMO
Peugeot iOn und Citroën C-Zero	CHAdeMO
Honda e	CCS

Multiple vehicle manufacturers have announced plans to offer electric vehicle models with bidirectional charging in the near future. There is a general consensus that 2025 will see the introduction of an international standard, which will also include binding rules on bidirectional charging via CCS connectors.

Years of practical experience and scientific testing have shown that lithium batteries are very robust. The latest technological developments have also led to further increases in battery lifespan. As the discharging capacity associated with bidirectional charging is far lower compared with actual driving (by a factor of 10 or more), any additional aging of the battery is negligible. Manufacturers’ approvals of vehicle models for bidirectional charging also state that all guarantees remain unaffected.

The intermediate storage and targeted recovery of self-generated solar power into the building increases the self-consumption rate for a property or area with photovoltaic systems, and therefore reduces the procurement costs for electrical energy. Bidirectional connection of vehicles also helps to mitigate peaks in electricity consumption as the batteries are discharged based on the load. This recovery process reduces the electricity costs for the user by enabling them to use a cheaper tariff. If there is a large enough number of vehicles returning energy to the grid, the capacity of the charging infrastructure may even come to exceed the delivery rate of the installed connection.

Pooled charging and discharging of vehicles can mitigate overloads on the grid, for example those caused by irregular sources of power generation such as solar and wind farms. 100’000 connected electric vehicles, each at ±10 kW, for example, represents a ±1 GW decentralised power source. This is the equivalent of Switzerland’s largest pumped storage plant at Limmern. Half of the energy that could be stored across the 100’000 batteries would be enough to supply 200’000 average single family homes with electricity for one day.

It doesn't work without a partner

It’s impossible without partners. A visit to the distribution grid operator Azienda Elettrica di Massagno (AEM) in Ticino shows how «V2X» works in a real environment. In Ticino, a number of houses have been linked together to form an energy consumption alliance. Here you can find out how the overproduction from photovoltaic systems is stored in the car’s batteries during the day. In the evening, when the PV systems are no longer producing electricity, the energy from the car flows back into the grid. The local electricity grid is only tapped when the energy is depleted.

Grid stability is also an important aspect. Experts in this field can be found at Zurich-based company «tiko». Here, you keep an eye on supply and demand and draw or feed electricity into the grid as required. Find out that grid stabilisation in Switzerland is technically feasible using V2X electric cars.