The electric car as a grid battery: where does Vehicle-to-Grid stand?

On 20 November 2025, the V2G Leaders Summit brought together more than 200 representatives from the European Commission, grid operators, manufacturers and researchers in Brussels. It was the first event of its kind organised by the Commission together with IEA Task 53. The conclusions were clear: the technology to use electric vehicle batteries as a grid resource already exists, but its deployment at scale remains held back by unresolved technical, regulatory and commercial issues. One year later, with the Commission’s Electrification Action Plan recently adopted and Italy finalising its regulatory framework for aggregated charging, the time is right to take stock.


What is V2G?

Vehicle-to-Grid refers to the possibility of allowing energy to flow in both directions between an electric car battery and the grid: not only charging the vehicle, but also feeding electricity back into the grid when needed. It is distinct from V1G, or unidirectional smart charging, which only adjusts charging times and power, and from V2H/V2B, Vehicle-to-Home/Building, where the car directly supplies a home or building without using the public grid.


What emerged from the Brussels summit

Beyond the institutional discussions, four main conclusions emerged from the summit.

First, scalability depends on interoperability, not on the availability of batteries or chargers. The first commercial solutions already work, but they rely on bilateral agreements and proprietary technology stacks between individual car manufacturers and individual energy operators. Without common standards, each implementation remains an isolated system.

Second, Member States do not need to wait for new European legislation before taking action. National regulatory sandboxes already allow them to test targeted exemptions from their own rules. This is the same approach that the Electrification Action Plan would formally establish a few months later.

Third, no single player can do it alone. The message from the closing sessions was that V2G can only create value when the energy, mobility and digital sectors work together, a principle that applies both at European level and, as we will see, within individual national value chains.

Fourth, data security governance remains an open and urgent issue, just as important as technical standards. The Commission’s Digital4Energy expert group and the Sustainable Transport Forum were identified as the key platforms where consensus will need to be built in the coming months. The next review has already been scheduled: V2G Leaders will return to Brussels in November 2026.


The technical challenge: standards that still do not speak the same language

The most frequently cited problem at the summit was interoperability between vehicles and charging points. The standard designed to address this issue is ISO 15118-20, the EV-EVSE communication protocol that will become mandatory for new or upgraded public and private charging points from 1 January 2027.

The problem is that implementation is still at an early stage. When different systems interact, they often fail to recognise each other correctly, typically resulting in an error message that prevents the charging session from starting.

The situation is further complicated by delays in implementing the network codes on Requirements for Generators, or RfG, which are expected to define how vehicles and bidirectional chargers technically connect to the electricity grid. Without these rules, manufacturers and operators continue to develop proprietary solutions.

On this front, IEA Task 53 is building a network of testing laboratories across three continents, with the aim of reaching a shared agreement by 2028 on the basic components required for certification.

The open-source community is also making an indirect contribution. The involvement of projects such as EVEREST in formal standardisation processes is seen as a way to make standards development more agile, as the current process is too slow compared with the pace of innovation in the sector.


Results from the European FLOW project

Much of what is currently known about the practical barriers to V2G comes from a single Horizon Europe project, FLOW. Launched in July 2022 and running for four years, the project involves a consortium of 30 organisations from nine countries and has a budget of more than €9.8 million.

Terna is participating in the project and is responsible for the Italian demonstrator, providing its Crowd Balancing Platform as an orchestrator between stakeholders and its E-mobility Lab to characterise the performance of the assets involved. The project includes five demonstrators in the Czech Republic, Ireland, Italy, Denmark and Spain.

The barriers identified by the project fall into five areas: users, technology, costs, regulation and markets. Among the most significant are the double taxation of electricity exchanged with the grid several times a day, the cost of bidirectional chargers, uncertainty over the role of aggregators and battery degradation, which varies depending on cell chemistry. LFP performs better than NMC, which is more sensitive to depth of discharge.

As for the services that can be provided, the framework identifies three levels: behind the meter, distribution and transmission. The potential value increases across these levels, but so does the complexity of coordination.

Consistent with these findings, Terna remains cautious about V2G at system level. The technology is not yet mature enough to make a significant contribution to large-scale flexibility because of the difficulty of ensuring the observability, measurability and controllability of bidirectional flows at costs compatible with an aggregator’s business model.

In the short to medium term, the operator therefore sees V1G as the main source of flexibility expected from electric mobility.


Italy introduces a standard: the CIR

While at European level the focus remains on harmonising vehicle-to-charger standards, Italy has almost completed the regulatory framework for a different part of the challenge: the aggregation of private charging, including residential, condominium and company charging.

The framework has been developed over a few years through joint work by CEI, ARERA and RSE.

At the centre of the system is a device called the CIR, or Charging Infrastructure Controller, designed to integrate electric vehicles into the electricity grid effectively and economically, both through unidirectional smart charging, V1G, and bidirectional charging.

The device is installed at the charging point and collects electrical and contractual data from the user. It communicates with the wallbox to adjust or suspend the charging session and independently runs a local control system, known as power management, which always guarantees continuity of electricity supply to the user before executing any external commands.

On the other side of the interface is the RO, the Remote Operator: an entity, such as an aggregator, balance service provider or energy community manager, authorised to operate in the flexibility services market.

One important technical detail is that the CIR uses the Chain2 infrastructure of second-generation smart meters, which are already installed at more than 98% of Italian connection points. This avoids the need to install new smart meters or dedicated communication lines.

Mandatory functions also include an automatic response to grid underfrequency. Each CIR suspends charging when the frequency falls below a certain threshold. The mechanism operates locally, without waiting for the remote operator, helping to provide primary frequency regulation for the system.

The regulatory pathway is structured across several levels. At the top is the European RED III Directive, which introduces control and flexibility principles for smart charging.

Italian Legislative Decree No. 5 of 9 January 2026, which transposes the directive into Italian law, introduces the new Article 45-bis into the Renewable Energy Decree, Legislative Decree 199/2021. It establishes 30 June 2026 as the date from which newly installed or replaced standard-power charging points that are not publicly accessible must have a compliant CIR.

Through its Technical Committee 316, CEI made Annex X of the CEI 0-21 standard mandatory, itself referenced by CEI PAS 57-127 for the interface with the remote operator, setting the effective mandatory date at 1 January 2027. This is the same date on which the ISO 15118-20 standard becomes mandatory at European level.

The regulatory process was accompanied by two phases of field testing conducted by RSE, the second involving 13 partners from industry, aggregators, CPOs and universities, as well as ARERA resolutions 634/2023/R/eel and 22/2025/R/eel, which defined the regulatory framework.

How much is this flexibility actually worth? RSE estimates based on Italy’s 2030 PNIEC scenarios indicate potential for a national aggregate of around 3,837 MWh per day, equivalent to around 23% of the secondary reserve procured daily by Terna.

With the number of vehicles currently on Italian roads, around 300,000 units, the potential today falls to 267 MWh per day, equivalent to 1.6% of the same reserve. This figure clearly illustrates the gap between theoretical potential and what can be activated in the short term, and helps explain Terna’s cautious approach mentioned above.


The European regulatory framework is moving forward

It was not until 2026 that the first shared rules began to emerge. The Electrification Action Plan, adopted by the European Commission on 17 July 2026, translates the demands that emerged in Brussels into actions with specific deadlines.

The first measure concerns regulatory experimentation. The Commission will launch a framework for regulatory sandboxes and living labs in Member States, designed to enable new V2G business models without having to wait for comprehensive European legislation.

It formalises a principle already discussed at the November summit: countries that want to move faster can do so by introducing controlled deviations from their national regulations.

On the demand side, by mid-2027 the Commission will assess and promote the introduction of smart charging as a default option in electricity supply contracts linked to EVs. This would shift the responsibility away from users, who currently have to activate smart functions voluntarily, to suppliers, which would be required to offer them as the default setting.

The most structural change, however, concerns the vehicles themselves. By the end of 2027, the Commission will introduce mandatory V2G requirements for new electric vehicles placed on the European Union’s internal market from 2030, including technical interoperability requirements such as standardised communication protocols.

This is the measure with the most direct impact on the industrial value chain. For the first time, the ability to discharge a battery back into the grid would become a vehicle approval requirement rather than an optional feature left to the commercial decisions of individual manufacturers.

The plan also looks beyond mobility itself. A review of the AFIR Regulation is planned to further support the deployment of charging infrastructure, alongside support for the development, by 2027, of a common methodology to assess flexibility potential across different industrial sectors and data centres. The aim is to address the knowledge gap surrounding an emerging flexibility segment that extends beyond EVs.

Linked to this, the plan also provides for a common EU energy rating scheme for data centres, with the aim of increasing transparency over energy consumption and introducing minimum performance standards that recognise their flexibility potential.

One regulatory element is already in force: Article 20a of RED III. Its implementation was clarified by a Commission communication shortly before the summit and requires battery-related data to be shared free of charge and in real time. The sector considers this a prerequisite, rather than simply a technical detail, for any scalable flexibility service.

At the same time, at Member State level, Germany has begun reviewing its regulations to provide more favourable conditions for residential energy storage and V2G, particularly by addressing double taxation, the same obstacle that the FLOW deliverable classifies as “major”.

Taken as a whole, the package sets out a fairly clear timeline: regulatory sandboxes and smart charging by default in 2026-2027, V2G requirements defined by the end of 2027, and an effective obligation for new vehicles from 2030.

This is the window in which the value chain, including manufacturers, CPOs, aggregators, TSOs and DSOs, will have to decide whether to be ready or be left playing catch-up.



This article was realized in collaboration with Rinnovabili.