According to a study by the International Energy Agency, 200–300 million electric vehicles (EVs) are expected to be on the roads worldwide by 2030, and the trend continues to rise. This means EVs will play an increasingly important role in energy distribution within tomorrow’s dynamic, intelligently managed power grids. Not only will EVs act as energy consumers, but they will also store electricity and feed it back into the grid when required. They can function as intermediate storage to balance fluctuations in renewable energy production and stabilize the power supply. The ISO 15118 protocol creates the technical foundation for this bidirectional interaction known as Vehicle-to-Grid (V2G).
ISO 15118: Enabler of smart and bidirectional charging
The ISO 15118 protocol acts as a common standard, defining the fundamentals of charging communication between the charging infrastructure, electric vehicle, and, where applicable, backend systems such as energy management platforms.As part of the Combined Charging System (CCS), it uses Power Line Communication (PLC) over the charging cable to enable secure and seamless data exchange during the charging process. It is the first protocol to natively support bidirectional charging introduced with ISO 15118-20, enabling the flexible use of electric vehicles as distributed energy storage units within the power grid.
With planned charging in V1G mode, a simple form of demand management is employed, typically shifting charging to off-peak hours when electricity is cheaper and grid stress is lower. V1G, supported by ISO 15118-2, enables unidirectional charging with intelligent scheduling and dynamic load adjustment based on external signals such as grid conditions, electricity pricing, or user preferences without feeding energy back into the grid.
The other charging mode described is V2G. In this mode, external energy management systems can be integrated to make decisions based on real-time grid conditions and projected loads, enabling truly “smart charging” capabilities. Since the charging process is managed through coordination between the charging station and backend systems, infrastructure and grid operators can influence charging behavior on a large scale via connected EVs participating in the smart grid. This includes slowing down or pausing charging or even feeding energy back into the grid during peak demand periods. For operators of EV fleets, such as logistics providers or public transport networks, this opens up a potential new revenue stream: they can make the unused battery capacity of parked vehicles temporarily available to the grid, offering valuable flexibility services to energy providers.
Finally, ISO 15118 ensures encrypted communication and, through standardized automatic authentication, lays the groundwork for Plug & Charge (PnC), making charging at public stations easier for users and enabling additional services.
Stronger Together: How standards enable V2G interoperability
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For Vehicle-to-Grid (V2G) to function at scale, close cooperation is required between all key stakeholders—vehicle manufacturers, charge point operators (CPOs), grid operators, and mobility service providers. The foundation of this collaboration lies in standardized communication protocols that ensure full interoperability across the ecosystem.
Three key standards are essential for enabling seamless interaction between electric vehicles (EVs), charging infrastructure (EVSE), and energy or mobility platforms (EMSP):
- ISO 15118 defines the communication between the EV and the charging station (EVSE), including support for Plug & Charge and bidirectional energy transfer.
- OCPP 2.x (Open Charge Point Protocol) governs the communication between the EVSE and the CPO’s backend systems, acting as the universal language for managing charging stations. With the release of OCPP 2.1 (expected in early 2025), support for ISO 15118-20 and advanced V2X functions such as DER integration and battery swapping will be included.
- OCPI (Open Charge Point Interface) facilitates communication between CPOs and EMSPs, providing a standard for roaming and service provisioning across networks.
True V2G functionality depends on the coordinated implementation of all three protocols. Only when OEMs, CPOs, and service providers align on this technical foundation can smart, bidirectional energy exchange become a stable and scalable reality.
As a trusted software engineering partner, Intellias supports companies across the value chain in aligning with these standards developing robust, future-proof applications that enable smart charging and V2G functionality from the ground up.
The potential role of EVs as active participants in grid balancing and distributed energy storage is clear and the technology is largely in place. But where does the industry stand when it comes to real-world implementation?
Global V2G adoption: Regional strategies and challenges
Car manufacturers are increasingly integrating ISO 15118 into their EV models, especially newer generations. The trend continues to gain momentum globally, making V2G capabilities more commonplace in electric vehicles.
While the global V2G market is poised for significant growth driven by rising EV adoption and the need for grid flexibility, implementation strategies vary by region.
EU: Adaption is regulatory-driven
In Europe, V2G adoption is largely shaped by regulation. Frameworks such as the “Fit for 55” package, the Alternative Fuels Infrastructure Regulation (AFIR), and EU rules for the Trans-European Transport Network emphasize interoperability and grid integration. Pilot projects in countries like the Netherlands, Denmark, France, and the UK are actively testing the technical and economic viability of V2G.
USA: Market-driven momentum
In contrast, the U.S. market is defined by a more decentralized and market-led approach. Progress is often driven by individual states, utilities, and private initiatives rather than federal mandates. Financial incentives for EVs and charging infrastructure in some states help strengthen the business case for V2G.
China: Technology in focus
China, the world’s largest EV market, is implementing a government-led, technology-focused strategy to become a global leader in V2G leveraging its massive EV fleet to enhance energy security, manage its rapidly growing electricity demand, and support the integration of renewable energy resources.
The Chinese government defined a clear roadmap for the development and deployment of V2G technology. With the strong collaboration between the government, state-owned grid operators, and domestic automotive and battery manufacturers China may take a leading role in establishing V2G standards globally.
The success and speed of V2G adoption in each region will ultimately depend on overcoming common challenges such as the high cost of bidirectional chargers, concerns about battery degradation, and the need for robust and secure communication protocols.
Infrastructure bottlenecks remain unsettled
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Despite promising developments, the charging infrastructure sector remains fragmented. Various protocols are used for communication between EVs and charging stations, ranging from proprietary solutions to open standards like OCPP and OCPI. While these protocols are evolving to align with ISO 15118, only a limited number of charging station manufacturers (e.g. Siemens, ABB) currently offer full ISO 15118 support.
In many existing installations, legacy hardware still relies on outdated communication standards. While software updates may enable ISO 15118 compatibility in some cases, widespread V2G deployment will likely require significant hardware upgrades, entailing higher investment and time to scale.
Examples of V2G in practice
Various players in the field of smart charging and V2G have already launched pilot projects and are actively testing real-world applications. Here are three examples, each involving different stakeholders and strategic approaches:
- Car Sharing: An initiative in Utrecht, Netherlands, involving Renault Group, aims to deploy 500 Renault 5 EVs equipped with Mobilize V2G technology for a car-sharing service.
- EV fleets: The Beverly Public Schools district in Massachusetts, partnered to utilize bidirectional chargers to generate revenue and support grid stability during peak demand, particularly in summer.
- OEM initiatives and use cases: Several automakers are integrating bidirectional capabilities. For instance, the Ford F-150 Lightning offers V2H via its Intelligent Backup Power system. GM is rolling out V2H across its Ultium platform EVs by the 2026 model year via GM Energy offerings. And Nissan continues V2G efforts, approving Fermata Energy’s bidirectional charger in 2024.
Final word
V2G is seen worldwide as an opportunity and is already being implemented in eMobility projects worldwide. The next step is to quickly establish the necessary frameworks and standards so that project participants can finally move beyond pilot projects, but this will require everyone to pull together!
Contact Intellias and let us help you integrate V2G solutions into your network for efficient and robust charging and EV management.
