Bidirectional charging – a primer

Bidirectional charging turns electric vehicle batteries into flexible energy storage systems. With bidirectional charging, electricity can flow in both directions: from the grid or the vehicle owner’s photovoltaic system into the car, and from the car back into the home (Vehicle-to-Home, V2H) or into the power grid (Vehicle-to-Grid, V2G). The absorption and discharge of electricity by the drive battery can both be controlled according to specific criteria. This targeted control of absorption is therefore also referred to as controlled charging. For example, the charging process may not start until a particularly large amount of renewable electricity is available, or the charging power may vary depending on how much capacity is available on the power grid. Bidirectional charging also includes the targeted feed-in of electricity.

Bidirectional charging turns a parked car into a source of income. Cars are usually on the road for only a few hours a day. Thanks to bidirectional charging, even the time electric cars spend parked can be put to good use. Longer periods of inactivity, such as at home or at work, are particularly well-suited for this. Charging speed is less of a concern in these cases. For EV users, the most important thing is that the battery is sufficiently charged when the vehicle is needed again. Software services can be used to set a minimum charge level for this purpose. If users make their parked car available as flexible storage, they can significantly reduce their driving costs, because storage flexibility provides financial value. The impact on the vehicle battery is minimal, provided that the charging and discharging processes primarily take place within the 40 to 70 percent range of the battery’s capacity.¹

Dynamic electricity prices create effective incentives for customers to take advantage of their flexibility and engage in bidirectional charging. Static rates change only at fixed times, such as through higher prices during midday or evening peak hours or between seasons. In contrast, dynamic rates vary in real time based on factors such as grid conditions, electricity market prices, or the availability of renewable energy sources. They offer car owners stronger incentives to adjust their consumption.

The capability for bidirectional charging will increase significantly in the coming years. So far, only a few charging stations and vehicles are designed for bidirectional charging. While approximately 25 vehicle models or about one-fifth of the electric vehicles newly registered each year are technically capable of bidirectional charging, this functionality is often limited to charging electrical devices, such as e-bikes or laptops (Vehicle-to-Load, V2L). A factor supporting a faster and more far-reaching transformation is that the CCS standard (Combined Charging System for charging with direct and alternating current), which dominates in Europe, has been expanded to include specifications for bidirectional charging in accordance with the standards of the International Organisation for Standardization (ISO). Various commercial offerings currently entering the European market underscore this development.³

In Germany, the key framework conditions for bidirectional charging have been established. Particularly as a result of the European Electricity Market Directive, the number of available dynamic electricity tariffs has risen significantly – from around ten offerings in 2021 to about 90 in 2023. Since April 2025, grid operators have been required to offer time-variable grid fees – though so far, only a few grid operators have complied with this requirement.⁴ The Federal Network Agency plans to implement a regulation by the end of 2026 that would exempt a large portion of the grid fees for electricity temporarily stored in vehicles. This could yield significant economic benefits for vehicle-to-grid applications, given that these fees account for about a quarter of the electricity price. The “Coalition of the Willing for Bidirectional Charging,” initiated in 2023 by the federal government and backed by European industry, is also promoting the EU-wide harmonisation of standards for bidirectional charging. 

Germany is making slow progress in the digitalisation of its electricity infrastructure, particularly in the rollout of smart meters. By 2025, fewer than five percent of households had smart metering systems.⁵ According to various company representatives, this is due in particular to the highly complex requirements for the devices and to the significant amount of red tape, such as that involved in certification.⁶ Other European countries are further along in the rollout of smart meters. In Austria, Italy, France, Spain, the Netherlands, Denmark, and several other countries, coverage already exceeds 80 percent of households. Another obstacle to the digitalisation of Germany's electricity infrastructure stems from regional variations in regulations governing grid connection and usage.

Leading European markets for EVs are driving the development of bidirectional charging – despite ongoing hurdles. In the Netherlands, V2G business models have so far been only marginally economically viable; unresolved issues regarding protocols and standards are slowing progress. Nevertheless, close cooperation between grid operators and providers, as well as pilot projects, are promoting market adoption. In France, the exemption from grid fees makes V2G economically attractive, and the centralised market structure creates favourable conditions. However, grid operators are currently focusing particularly on grid expansion and other flexibility solutions, such as a capacity market for electricity generation. In the United Kingdom, V2G applications can already be operated profitably. However, there is still a need for regulatory adjustments, for example regarding the certification of chargers. Progress in bidirectional charging in Europe is expected to accelerate, primarily due to the European Commission’s recently published Electrification Action Plan. This document explicitly addresses the widespread adoption of bidirectional charging as part of the European electrification strategy. For example, the Commission plans to introduce requirements for EVs registered in the EU starting in 2030 that enable bidirectional charging – for instance, through standardised communication protocols.