CharIN Testival 2026: interoperability remains a key challenge

At the CharIN Testival & Conference Europe, we took a closer look at the topics currently occupying the charging industry. The focus was not only on higher charging power but, above all, the question of how reliably vehicles, charging stations, and the power grid will all interact in future.

CharIN also tests MCS systems for e-trucks at the Testival.

Image: Phoenix Contact

The demonstration was supposed to focus on high-power charging. A Mercedes-AMG was parked at the charging station, the plug is connected, but initially, the charging process did not start. It then took several attempts before the vehicle and the charging station communicate with each other. Ironically, the high-powered charging demonstration vividly illustrated what the CharIN Testival is always about: interoperability remains a central challenge for the charging industry, even in 2026.

At the Testival, vehicles and charging systems from different manufacturers meet under controlled conditions. These include vehicles and technologies that have not yet been officially unveiled. CharIN itself places interoperability tests at the heart of the event; as host, Phoenix Contact provides, among other things, a CCS charging point with up to 720 kW for performance testing at its site.

In an interview with _electrive_, CharIN CTO Michael Keller described the principle as a kind of “speed dating” between the vehicle and the charging hardware. For the end user, the decisive factor is that these combinations work regardless of the manufacturer. “Without 100% interoperability, the customer has no guarantee of a successful charging process when they arrive at an unfamiliar charging station,” he said.

What’s already clear is that the simple act of starting a charging process becomes more complex with each additional function. Plug & Charge, Smart Charging, higher charging power, and bidirectional energy flow not only require suitable hardware but also a uniform implementation of communication standards.

CharIN expands interoperability with ISO 15118-20

Keller sees the greatest progress compared to last year in ISO 15118-20. “It is already surprising how many have now reached the point of actually implementing this standard in vehicles for testing and, in some cases, already have it in use in vehicles,” he said.

The standard describes the second generation of communication between electric vehicles and charging infrastructure. In July 2026, an amendment was published with ISO 15118-20:2022/Amd 1:2026, which, among other things, includes MCS services, AC-DER applications for grid integration, and a revised security concept.

This raises an important distinction: ISO 15118-20 does not describe the MCS plug itself. The physical MCS interface is specified via IEC TS 63379. At the CharIN Testival in Arnhem in May, the test fields included ISO 15118-20 Amendment 1, TLS 1.3, and the mechanical compatibility of the MCS plug and inlet. CharIN identified a need for improvement, particularly in compatibility and locking mechanisms.

This shows why the publication of a standard alone is not sufficient. Vehicle, charger, and component manufacturers must implement it in such a way that different products actually work together. For MCS, Keller sees the foundations largely in place. Since 2018, CharIN has been working on the system with more than 120 members. “There are enough charging stations available for purchase. There are already trucks equipped with it, but not yet in the required volume,” he says.

The Testival also demonstrates how concrete the applications have become. Presentations mention up to 1,000 kW MCS charging power for the Mercedes-Benz eActros 600, 750 kW for the MAN eTGX, and 700 kW for the Volvo FH Aero Electric. At the same time, charging is increasingly being considered during vehicle development for heavy-duty commercial vehicles.

This has implications far beyond the actual charging process. The position of the charging port, for example, affects cable routing, parking space design, and traffic flow in a charging park. With megawatt-level power, grid connection, load management, and stationary battery storage also become central planning factors.

Nevertheless, there are good prerequisites for a relatively rapid ramp-up in the case of e-trucks. MCS could make a decisive contribution to the operational capability of electric trucks, particularly in long-haul transport. The remaining chicken-and-egg problem lies less in the fundamental technical feasibility and more in the parallel ramp-up of vehicles and infrastructure.

Interoperability becomes even more complex with Vehicle-to-Grid. Communication between the vehicle and the charging point is no longer sufficient. Energy management, backends, and signals from the power grid must also be integrated. “We must be able to use vehicle batteries flexibly for the power grid and to stabilise energy supply – that is a major issue,” says CharIN CTO Michael Keller. This requires “many players to work together.” The expanded requirements were already evident at the CharIN Testival in Arnhem in May. There, 13 out of 23 DC test systems supported bidirectional energy flow; for AC, it was 7 out of 11. For more realistic tests, grid emulators were also used. However, CharIN still considers V2G implementations and compliance tests with European grid requirements to be at a relatively early stage of development.

Cybersecurity is also gaining importance. ISO 15118-20 and the 2026 amendment expand the possibilities for MCS and grid integration, among other things, and further develop the security concept. The more automated charging processes become and the more they are linked to the energy system, the more communication paths need to be secured.

Technology is not the only bottleneck

The fact that the challenge now extends beyond the vehicle and charging station was also clear on Public Day. There, representatives from local government, the electrical industry, and standardisation discussed the practical hurdles of expansion under the title ‘Mobility and Energy Transition: Implementation Begins Locally’. CharIN itself explicitly focuses on the connection between charging infrastructure and the energy system at the event.

Meinolf Haase, District Administrator of the Lippe district, referred to experiences from municipal practice. According to him, around half of the public fleet (DE) of the district is now electrified; at the same time, municipal properties are to be equipped with more photovoltaic systems. Not every political directive makes local implementation easier. With a view to contradictory requirements from Berlin, Haase succinctly summarised the problem as “wash me, but don’t get me wet.”

For Claudia Lorenz, Managing Director of the Energy Technology Association within ZVEI, one of the central tasks is the expansion of the power grid. The association sees significant investment needs here – not least because additional charging infrastructure, heat pumps, and decentralised generation simultaneously place new demands on distribution networks. “The technology is there; in some places, it fails due to a lack of political will,” said Lorenz in Blomberg. How quickly charging parks or private charging points can be implemented increasingly depends on the local grid capacity and how quickly a connection can be processed.

How varied these prerequisites can be is also shown by Germany’s grid structure. The Federal Network Agency now publishes key figures on how long individual distribution network operators take to process grid connections and the extent to which their processes are digitised, precisely because performance and implementation speed vary regionally.

Dennis Heusser from the Energy Technology Society in VDE, on the other hand, focused on the common technical basis: “Standards and norms create trust.” This applies to conventional charging as well as to MCS or V2G. The more actors involved, the more important binding interfaces become to ensure that vehicles, charging hardware, grid technology, and backends do not only function within individual ecosystems. His statement thus captures the core of the Testival: a standard on paper is only valuable when different implementations work together in real-world interaction.

For charging park and fleet operators, this shifts the decisive question. It is no longer just about the maximum kilowatt rating of a charging point but whether the vehicle, charging hardware, backend, grid connection, and regulatory processes work together. With MCS, the physical design of the charging park is added to the equation; with V2G, the system boundary extends into the power grid.

This is precisely why testing and certification processes are likely to gain in importance. The more functions are based on ISO 15118-20, the greater the number of possible interfaces, and the earlier manufacturers need to test their systems against each other. CharIN accordingly describes its Testivals as a real-world testing environment for the interoperability of vehicles, charging infrastructure, and other components of the e-mobility ecosystem.