What the project delivered
Two results stand out. The first is technical: a prototype that can push power back through CCS, the DC connection European drivers already meet on motorways and at fast chargers. The project describes this as a critical component for wider adoption, because energy can only flow out of a car through an interface that exists in the real world and not only in a laboratory.
The second is software. The partners wrote open-source tools that let charging point operators handle communication based on standards for smart and bidirectional charging. That matters for the unglamorous question of who is responsible when a car discharges into the grid and something goes wrong along the chain.
The batteries themselves were managed through a virtual power plant, which pools many vehicles and offers their capacity on energy markets. "This approach can increase revenue while delivering direct benefits to users," said project coordinator Hugo Morais. The condition attached to that sentence is the one families will recognise: cars have to be plugged in when the market wants them, and owners have to allow flexibility over when charging starts and stops.
Pooling parked batteries is not the only model being tested. In China, Nio recorded 1,192,221 battery swaps in seven days, with each station handling 6% more swaps than in May. Swapping and discharging are different answers to the same question of how a grid uses cars that are standing still.
Four pilots, four sets of results
Portugal. Unidirectional and bidirectional charging points were integrated into residential buildings and public facilities. The demonstration showed an average reduction in charging costs for private households of 8.6%, and up to 21.9% higher integration of renewable energy.
Slovenia. The work there focused on virtual power plants and local market platforms in office and school buildings. The trials confirmed added value for V2X compared with purely smart charging, which only shifts the timing of consumption.
Greece. In Athens, flexible capacity contracts and dynamic price signals were tested as a way to limit overloading and high power demand at public charging locations.
Denmark. Control algorithms managed charging groups in car parks, with the aim of reducing phase imbalances and improving the local use of renewable generation.
What 8.6% is worth in a family budget
The Portuguese figure is the one most readers can put to use. Take a household that drives 15,000 km a year in an electric car consuming 18 kWh/100 km. That is 2,700 kWh. At a home tariff of roughly €0.22 per kWh, the annual charging bill comes to about €594. A cut of 8.6% would save some €51 over the year.
That is not a sum that changes a family's finances. It also comes from one pilot with its own tariffs, cars and control software, so it is an indication rather than a promise. If you want to see what your own mileage and contract produce, our charging cost calculator takes a few minutes.
The renewable figure is the more significant one for the grid side: up to 21.9% more local renewable generation absorbed in the Portuguese demonstration, according to the project.
Battery ageing and the owner's veto
The project is direct about one limit. Bidirectional charging works as a flexibility option only if the owner's mobility needs are met and battery ageing is taken into account. Control algorithms can reduce the extra stress on the pack, but they cannot remove it.
Work on that problem continues outside this project. A simulation from Chalmers University found that a bypass path around individual cells could add about 14 months of pack life in an 80 kWh battery, which is the kind of durability question buyers ask before they let a utility borrow their car.
What to check before you buy
If bidirectional charging is on your list, do not stop at the phrase "V2X ready" in a brochure. Ask which direction the car actually supports, whether it works over DC through CCS, and whether a compatible charger is sold and approved in your country. Support depends on the model and its software, and the EV4EU prototype shows the return path is technically possible on CCS, not that every car with a CCS socket can do it. Our EV catalog is a reasonable place to start comparing models.
Policy matters just as much, because most business models need a tariff or market rule that pays for the service. That framework is still being written in Europe, and even the 2035 target is in play: France and Germany want the planned 100% cut in new car CO2 emissions lowered to 80%, with a proposal due on 15 October.
The consortium's own conclusion is that V2X requires coordinated communication, suitable market models and incentives for participants before it can scale. Its tested hardware and software are the starting point. The next step named by the project is applying them under each country's grid and market conditions.
Can I use bidirectional charging with the car I own today?
Only if the car and the charger both support it. The EV4EU prototype uses CCS, the DC standard used across Europe, but whether a specific model can send power back is decided by the manufacturer and the software version. Check the specification before you assume it.
What happens if the car is discharging and I need to leave?
The project treats this as a condition rather than a detail: mobility requirements have to be guaranteed and the owner has to accept flexibility in charging and discharging. In practice, the control software has to know when you next need the car, so it can hold enough charge.
Source: https://www.electrive.com/2026/10/10/ev4eu-project-advances-bidirectional-charging/