The demonstration was supposed to focus on high-power charging. A Mercedes-AMG was parked at the charging station with the plug connected, but at first the charging process did not start. It then took several attempts before the vehicle and the charging station communicated with each other. Ironically, the high-power charging demonstration vividly illustrated what the CharIN Testival is always about: interoperability remains a core challenge for the charging industry, even in 2026.
The Testival brings together vehicles and charging systems from different manufacturers under controlled conditions. These include vehicles and technologies that have not yet been officially presented. CharIN itself places interoperability testing at the center of the event; As a host, Phoenix Contact offers, among other things, a CCS charging point with up to 720 kW for performance testing at your premises.
In an interview with electricCharIN 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 independently of the manufacturer. “Without 100% interoperability, the customer has no guarantee of a successful charging process when arriving at an unknown charging station,” he said.
What is already clear is that the simple act of initiating a charging process becomes more complex with each additional function. Plug & Charge, Smart Charging, higher charging power and bi-directional power flow require not only suitable hardware, but also a uniform implementation of communication standards.
CharIN expands interoperability with ISO 15118-20
Keller sees the most progress compared to last year in the ISO 15118-20 standard. “It’s already surprising how many have gotten to the point of 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. An amendment to ISO 15118-20:2022/Amd 1:2026 was published in July 2026, which, among other things, includes MCS services, AC-DER applications for network integration and a revised security concept.
This raises an important distinction: ISO 15118-20 does not describe the MCS socket itself. The MCS physical interface is specified through IEC TS 63379. At the CharIN Testival in Arnhem in May, testing areas included ISO 15118-20 Amendment 1, TLS 1.3 and the mechanical compatibility of the MCS connector and input. CharIN identified a need for improvement, particularly in compatibility and locking mechanisms.
This demonstrates why publishing a standard alone is not enough. Manufacturers of vehicles, chargers and components must implement it in such a way that the different products actually work together. For MCS, Keller believes the foundations are practically established. Since 2018, CharIN has been working on the system with more than 120 members. “There are enough charging stations for sale. There are already trucks equipped with them, but not yet in the necessary volume,” he says.
The Testival also demonstrates how concrete applications have become. The presentations mention an MCS charging power of up to 1,000 kW 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, cargo is increasingly being considered during the development of heavy commercial vehicles.
This has implications far beyond the actual charging process. The position of the charging port, for example, affects cable routing, parking space layout, and traffic flow in a charging park. With megawatt power, grid connection, load management and stationary battery storage also become central planning factors.
However, there are good prerequisites for a relatively rapid increase in the case of electric trucks. MCS could make a decisive contribution to the operational capacity of electric trucks, especially in long-distance transportation. The remaining chicken and egg problem lies less in fundamental technical feasibility and more in the parallel increase in 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 power grid signals must also be integrated. “We need to be able to use vehicle batteries flexibly for the power grid and stabilize the power supply – that’s an important issue,” says CharIN CTO Michael Keller. This requires “many actors working together.” The expanded requirements were already evident at the CharIN Testival in Arnhem in May. There, 13 of 23 DC test systems supported bidirectional power flow; for AC, it was 7 out of 11. For more realistic tests, network emulators were also used. However, CharIN still considers V2G implementations and testing for compliance with European network requirements to be at a relatively early stage of development.
Cybersecurity is also gaining importance. ISO 15118-20 and the 2026 amendment expand, among other things, the possibilities of MCS and network integration and further develop the security concept. The more automated charging processes become and the more linked they are to the energy system, the more communication paths will need to be protected.
Technology is not the only obstacle
The fact that the challenge now goes beyond the vehicle and the charging station was also made clear at Public Day. There, representatives from local governments, the electricity industry and standardization discussed the practical obstacles to expansion under the title “Mobility and energy transition: implementation starts locally.” CharIN itself explicitly focuses on the connection between charging infrastructure and the energy system.
Meinolf Haase, district administrator of Lippe, referred to experiences from municipal practice. According to him, approximately half of the district’s public fleet (DE) is electrified; At the same time, municipal properties will be equipped with more photovoltaic systems. Not all policy directives facilitate local implementation. Faced with Berlin’s contradictory demands, Haase succinctly summarized the problem in the following phrase: “Wash me, but don’t get me wet.”
For Claudia Lorenz, general director of the ZVEI Energy Technology Association, one of the central tasks is the expansion of the electrical grid. The association sees important investment needs here, not least because additional charging infrastructure, heat pumps and decentralized generation simultaneously place new demands on distribution networks. “The technology is there; in some places it fails due to lack of political will,” Lorenz said in Blomberg. How quickly charging parks or private charging points can be deployed increasingly depends on the capacity of the local network and how quickly a connection can be processed.
The variety of these prerequisites is also demonstrated by the grid structure of Germany. The Federal Network Agency is now publishing key figures on how long it takes individual distribution network operators to process network connections and to what extent their processes are digitalised, precisely because performance and implementation speed vary by region.
Dennis Heusser from the VDE Energy Technology Society, for his part, focused on the common technical basis: “Standards and norms create trust.” This applies to both conventional and MCS or V2G charging. The more actors involved, the more important binding interfaces will be to ensure that vehicles, charging hardware, network technology and backends do not operate only within individual ecosystems. His statement thus captures the core of Testival: a paper standard is only valuable when different implementations work together in real-world interaction.
For freight park and fleet operators, this changes the decisive question. It is no longer just about the maximum power in kilowatts 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; In V2G, the system boundaries extend to the power grid.
This is precisely why testing and certification processes are likely to gain in importance. The more functions based on ISO 15118-20, the greater the number of possible interfaces and the sooner manufacturers will have to test their systems against each other. Accordingly, CharIN describes its Testivals as a real-world testing environment for the interoperability of vehicles, charging infrastructure and other components of the electric mobility ecosystem.
