According to the International Energy Agency (IEA)*, by 2030 worldwide between 200 and 300 million electric vehicles will be on the roads – with an upward trend. This makes their role in intelligently managed power grids – the so-called Smart Grids – increasingly significant. Electric vehicles can not only absorb energy, but also store it and feed it back into the grid when needed. They thus act as decentralized buffer storage to balance fluctuations in the feed-in of renewable energy and to increase grid stability. The technical basis for this bidirectional energy exchange (Vehicle-to-Grid, V2G) is the communication protocol ISO 15118.
ISO 15118: Technological enabler for bidirectional and intelligent charging
As a cross-manufacturer standard, ISO 15118 defines the communication between electric vehicle, charging infrastructure and – where available – backend systems such as energy management platforms. As part of the Combined Charging System (CCS), the protocol uses Powerline Communication (PLC) over the charging cable to enable secure and seamless data transmission during the charging process.
With ISO 15118-20, bidirectional charging is fully supported for the first time. Electric vehicles can thus be flexibly integrated as decentralized energy storage into the power grid. In the so-called V1G mode (supported by ISO 15118-2) – i.e., during planned, unidirectional charging – the charging process can, for example, be shifted to grid-friendly, cost-effective time windows. The system responds dynamically to signals such as electricity prices, grid load, or user preferences.
The V2G mode goes one step further: discharging operations are also enabled. External energy management systems can make decisions based on current and forecasted grid conditions about when and how much energy to load or feed back. Infrastructure operators and
grid operators thereby gain a new instrument to manage grid utilization – for example by deliberately reducing charging power or feeding electricity into peak-load times.
New business models for fleets
For fleet operators in logistics or public transport, this opens up new business opportunities: The battery capacity of unused vehicles can be temporarily made available to the grid and marketed as a flexibility service.
In addition, ISO 15118 enables encrypted communication as well as standardized automatic authentication – the foundation for convenient Plug & Charge charging processes at public charging points.
Common standards create true V2G interoperability
For a scalable implementation of V2G, all involved actors must work closely together: vehicle manufacturers, charging point operators (CPOs), grid operators and mobility service providers. The technical basis for this is interoperable standards that enable uniform communication across the entire system landscape.
Three central protocols play a key role here:
ISO 15118: governs the communication between vehicle (EV) and charging point (EVSE), including plug & charge and bidirectional energy transfer.
OCPP 2.x (Open Charge Point Protocol): defines the interface between charging point (EVSE) and the backend system of the CPO – and thus serves as a universal “language” for managing charging stations. With the version expected in 2025, OCPP 2.1 will also support ISO 15118-20 as well as extended V2X features such as integration of distributed energy resources (DER) and battery swapping.
OCPI (Open Charge Point Interface): standardizes the communication between CPOs and E-Mobility-Service-Providers (EMSPs) – for example for roaming and service provision across network boundaries.
True V2G functionality can only be economically and technically meaningful if all three protocols are integrated. Only the joint implementation by OEMs, CPOs,
and EMSPs creates the necessary interoperability for a scalable, intelligent energy network. As an experienced partner for software engineering, Intellias supports companies along the entire value chain – from standard compliance to the development of intelligent backend solutions for smart charging and V2G.
The potential role of electric vehicles as active participants in grid stabilization and as decentralized energy storage is evident – and the technological basis for this is largely in place. But what about the practical implementation in the industry?
V2G worldwide: regional strategies and challenges
More and more car manufacturers equip their electric vehicles with ISO 15118, including especially newer model generations. The V2G capability is thus becoming the new standard. But in implementation, regional differences become evident:
Europe: Here legal requirements drive V2G development – for example through the “Fit for 55” package, the Alternative Fuels Infrastructure Regulation (AFIR) or EU requirements for the Trans-European Transport Network (TEN-V). Pilot projects in the Netherlands, Denmark, France and the United Kingdom are currently testing the technical and economic feasibility.
USA: The market is decentralized. Individual states, utilities or companies initiate projects. Subsidy programs for EVs and charging infrastructure in some states make V2G economically attractive – despite the lack of federal regulation.
China: As the world’s largest EV market, China pursues a state-guided, technologically focused approach. The goal is to use the national EV fleet for grid stabilization, meeting the growing energy demand and integration of renewable energies. A clear roadmap for V2G has been defined – supported by close cooperation between government, state grid operators and the domestic vehicle and battery industry.
Despite different approaches, all markets face similar challenges: high costs for
bidirectional charging devices, concerns about battery degradation, and the need for secure, robust communication interfaces.
Infrastructure as a bottleneck
The charging infrastructure remains a central impediment: while the vehicle side is rapidly upgrading, a large portion of today’s installed charging stations still rely on older, incompatible systems. Some components can be retrofitted via software update, but in many places hardware replacement will be necessary – with corresponding investment needs and time required.
Only a few manufacturers – including Siemens and ABB – currently offer charging solutions with full ISO-15118 support. Even as open standards like OCPP and OCPI continue to evolve, the path to widespread V2G integration remains long.
Practical insights: V2G projects worldwide
Numerous players are already testing V2G under real-world conditions. Three examples illustrate the diversity of possible applications:
In Utrecht (Netherlands), a fleet of 500 Renault 5s equipped with Mobilize-V2G technology is deployed in a car-sharing model – a European premiere.
In Massachusetts, a school district uses bidirectional charging devices to cushion peak loads in summer and generate revenue.
And Ford already enables V2H with the F-150 Lightning via “Intelligent Backup Power.” GM plans to introduce V2H by 2026 for all Ultium EVs. Nissan continues to rely on V2G and certified a bidirectional charger from Fermata Energy in 2024.
What does this mean?
V2G is seen worldwide as an opportunity and is being implemented in initial projects. Now it is a matter of quickly creating the necessary framework conditions and standards so that project participants can finally move beyond pilots – but for that, everyone must pull together!
https://www.iea.org/reports/global-ev-outlook-2024/outlook-for-electric-mobility
The research on the topic for us by Volodymyr Zavadko, Delivery Director, Head of
