What is bidirectional charging?
Bidirectional charging allows an electric vehicle to not only store electricity but also feed it back – for example to an appliance, the home network or the public electricity grid. The electricity flows in both directions.
What are the benefits of bidirectional charging for EV owners?
Bidirectional charging enables surplus electricity from a photovoltaic (PV) system or electricity purchased cheaply under a time-of-use tariff, to be temporarily stored in an electric vehicle. This means the electricity does not need to be fed into the grid immediately but can instead be used later in place of more expensive grid electricity (“vehicle-to-home”, or V2H) or fed back profitably into the public grid at a later stage (“vehicle-to-grid”, or V2G).
Dynamic electricity tariffs, where the price of electricity varies according to supply (cheaper when production is high and more expensive when supply is low), make this even more attractive. When grid electricity is inexpensive due to abundant supply, it can be stored in the car battery; later, when prices rise, it can either be used within the household or sold back to the grid. From 2025, all electricity suppliers will be required to offer at least one time-of-use tariff.
What are the benefits of bidirectional charging for the energy system?
Bidirectional charging also benefits the energy system as a whole. Collectively, millions of electric vehicles provide a significant flexibility buffer, which can help smooth short-term fluctuations in electricity supply from renewable sources, stabilise the grid and provide additional storage capacity.
What types of Bidirectional Charging are there?
Three main types of bidirectional charging can be distinguished:
- Vehicle-to-load (V2L) / vehicle-to-device (V2D): The electric vehicle is equipped with a standard household socket and acts as a mobile storage unit, capable of powering various devices – for example an electric grill, a garden tool, an e-bike, a battery pack, or even another electric vehicle.
- Vehicle-to-home (V2H): The electric vehicle serves as storage for the household, using self-generated PV electricity and/or electricity purchased at a favourable price. The stored electricity can then be used later instead of drawing more expensive power from the grid.
- Vehicle-to-grid (V2G): Rather than being used in the household, the stored electricity is fed back profitably into the public grid.
Can bidirectional charging already be used?
V2D and V2H are already possible today. For V2D, an electric vehicle only needs a household socket or a suitable adapter. V2H and V2G, by contrast, are more complex. The vehicle itself must be technically compatible, and a wall box is required that can also convert the direct current from the car battery back into alternating current for the electricity grid. Lists of which vehicle models and wall boxes are currently suitable for V2D and V2H can, for example, be found on the websites of well-known specialist magazines.
Bidirectional Charging – What still needs to be done?
The main technical and regulatory foundations for the introduction of V2H and V2G are already in place. However, the framework conditions still need to be adapted and improved. In particular, a common digital language and data-exchange platforms are required to enable all components – from the battery and vehicle to the wall box, energy management system and electricity grid – to communicate and interact fully automatically. Work on this is already well under way. The goal is to make commercial solutions available from 2025. To this end, on 27 November 2023 the Federal Ministry for Economic Affairs and Energy (BMWE) launched the cross-sector and cross-border industry initiative known as the European Coalition of the Willing for Bidirectional Charging (CoW).
European Coalition of the Willing for Bidirectional Charging (CoW)
The CoW aims to create a level playing field and a non-discriminatory regulatory environment for all companies and consumers in Europe.
The coalition has identified the technical data points and interfaces required for bidirectional charging and has set out regulatory recommendations in three reports.
The CoW brings together more than 150 experts from around 75 companies and organisations across Europe’s digital, energy and automotive sectors.
It is structured into four European working groups (EWGs):
- EWG 1 focuses on the interaction between vehicles, charging infrastructure, and the wider energy system.
- EWG 2 is concerned with the grid- and market-oriented integration of bidirectional charging into the electricity system.
- EWG 3 addresses legal and regulatory frameworks across Europe and within individual EU Member States.
- EWG 3a concentrates specifically on the legal and regulatory framework in Germany.
The CoW aims to make bidirectional charging market-ready by 2025 and to achieve widespread deployment across Europe by 2030. Its work focuses on interoperability and on developing common IT architectures, protocols, and interfaces to ensure that charging infrastructure functions seamlessly across sectors and borders, both technically and commercially. The EWGs carry out this work through joint workshops, the preparation of technical blueprints and the development of policy and regulatory recommendations. To support these processes efficiently, regular digital and in-person meetings are held at the BMWE. Cross-sector and cross-border collaboration plays a central role in creating Europe-wide interoperable digital charging infrastructures.
The CoW has already addressed challenges such as double taxation, the absence of price signals and incentives for consumers, and a lack of technical interfaces. To further promote deployment, the coalition recommends an experimental clause until 2030, exemptions from taxes and levies for electricity stored temporarily, and incentive schemes for consumers – for example, through dynamic tariffs.
The working group reports of the European Coalition of the Willing for Bidirectional Charging can be downloaded here:
These groups have identified the data and interfaces required to implement bidirectional charging across Europe. They also examine use cases such as private and public applications as well as multi-family housing. The roadmap foresees the first market-ready products by 2025, followed by scaling and broader market adoption.
European Coalition for bidirectional Charging - Report of the European Working Group 3 (PDF, 3 MB)
This report examines the legal and regulatory framework for bidirectional charging (V2G and V2H) in Europe. It highlights key challenges such as insufficiently defined statutory and regulatory provisions, the absence of incentives for industry and consumers, and technical barriers. The aim is to make interoperable products commercially available from 2025 and to enable broad adoption by 2030.
This report outlines the adjustments required in Germany’s regulatory framework to make bidirectional charging (V2G and V2H) economically viable and to position Germany as a lead market for electric mobility. Key proposals include the introduction of a simplified metering system, exemptions from taxes and levies for electricity stored temporarily, an extension of Section 14a of the Energy Industry Act (Energiewirtschaftsgesetz - EnWG) to allow more flexible electricity flow management, and the creation of a testbed environment until 2030.
