The vehicle-to-grid technology solution, also known as V2G or two-way charging, means that an electric car can not only charge its battery via the grid, but also deliver electricity back to the grid when needed.
Although it has been around since the 1990s, the technology has only been implemented commercially in vehicles and charging infrastructure in recent years. But the development has only just begun. Although there are currently around 1,000 electric car models worldwide, only a few support bi-directional AC charging. Exceptions include Volvo’s new EX90 electric SUV and all cars in Volkswagen’s ID range with batteries larger than 77 kWh.
However, development is progressing Fast. According to the EU Afir regulation, which already requires all public charging stations to support smart charging, V2G technology will be mandatory in all new charging infrastructure within the EU from 2027.
At the same time, several projects are underway to explore the possibilities of the technology, including the so-called PEPP project in Gothenburg, which aims to investigate how electric cars can be used as a resource for the electricity grid in the form of temporary energy storage.
As part of the project, which started in 2023 and recently completed, eleven charging points were installed at different locations in Gothenburg: Torslanda, Lindholmen and at World of Volvo. Several Volvo electric cars were used in the tests, including the new EX90 SUV.
Direct charging, smart charging and V2G were compared through simulations. The results varied depending on location and parking patterns, but on average, using V2G charging was almost 35 percent more economical than regular charging, according to Chalmers researcher David Steen, who is leading the project.
The effect was most noticeable in the long-term car park in Saltholmen, where many people leave their cars to take the ferry to the southern Gothenburg archipelago. There was a cost difference between the technicians of 57 percent.
– It’s not that surprising. The longer the car is parked, the greater the benefit of V2G, says David Steen.
However, the project shows that financial incentives are not always enough to get more people to adopt the technology. It takes more than that for a few to have a greater impact, says David Steen.
– There is great potential, especially when it comes to charging at home. But many people live in apartments and park on the street or in garages. You also have to get V2G there to have its full effect, he says.
One proposal that the project highlights is to reserve attractive parking spaces for those who use V2G to create more incentives than just money.
Electricity tariffs and different rules from network operators influence how profitable it is to charge or deliver electricity at different times of the day. And although the EU will require new chargers to be bidirectional from 2027, many questions remain unanswered about business models and technical standards.
– I think the technology has huge potential. But it’s important to think about how to make it easy and attractive for users, says David Steen.
Similar projects are underway also elsewhere in Sweden. Tranås Energi is currently taking part in a pilot project in which electric cars are used as a resource in the electricity grid through V2X technology, i.e. vehicle-to-everything. The University of Gävle is studying how parked electric cars can support the local power grid via V2G, and in Linköping, surveillance cars are to be connected to the power grid to smooth out power peaks.
Facts.Vehicle-to-what?
V2G (Vehicle to Grid)
Technology in which the electric car battery can send power back to the grid to balance the load or store excess power.
V2H (Vehicle to Home)
The battery of the electric car serves as a source of energy to operate a household, for example in the event of a power outage or to reduce electricity costs.
V2X (Vehicle to Everything)
Collective term for all technologies in which the battery of the electric car interacts with the environment, for example with the power grid, houses or other buildings.
V2B (Vehicle to Building)
The electric car battery supplies power to an entire building, such as an office or school, to reduce power peaks or as backup power.
Facts.Further projects in the vehicle-to-grid area
In a pilot project, Tranås Energi, together with Energikontor Norra Småland, will connect six work vehicles with V2X technology to recharge and feed electricity back into the grid. The aim is to make the capacity of the power grid more efficient and reduce the need for costly expansion. The aim of the two-year project is to address the increased load and complexity of the electrical system by using cars as a flexibility resource when parking. The collaboration includes Chalmers and Glava Energy Center.
The University of Gävle has launched a study to investigate how parked electric cars can support the local electricity grid through V2G technology. The project, which involves local electricity companies, aims to show how electric car owners can charge when electricity is cheap and sell it again when it is expensive. Challenges include car owner involvement and the cost of dedicated chargers. The study will last four years and is funded by the Swedish Energy Agency and the EU. A project in Linköping, led by the Norwegian Road and Transport Research Institute (VTI) and funded by Vinnova, plans to connect surveillance cars to the grid with bi-directional charging in one of the Dukaten car parks to study how electric cars can help smooth out power peaks. The project begins in January 2026 and runs until March 2029, with Tekniska Verken, Bixia, Re & Go and Knowit taking part, among others.
Read more about mobility and the green transformation of the transport sector at di.se/mobilitet
