Bidirectional charging: the 6 biggest questions and myths – and what's really true

Some people believe that all you need for a modern electric car is a new wallbox and you're ready to start storing electricity back and forth. However, only selected models and special charging stations currently support this function. This is because the direct current (DC) from the battery has to be converted into alternating current (AC) for the grid. The electric car thus becomes a power storage device. Not all electric cars can do this yet.

The good news is that more and more are becoming capable of doing so. Word has already spread in the energy and vehicle manufacturing world that this technology is the future.

For example, while the Nissan Leaf (with CHAdeMO) is technically ahead of the curve, popular models such as the VW ID. and Renault Zoe often still lack full support. You can read about which cars are already capable of bidirectional charging here.

The following wallboxes are currently capable of bidirectional charging:

• Zaptec Go wallbox
• Wallbox Quasar (UK)
• We Drive Solar Solar Life (NL)
• Alfen models "Plus" (NL)
• Indra (UK, coming up)
• Mobilize PowerBox Verso
• Others are already working on bidirectional models

It sounds logical: the more often you charge and discharge, the more wear and tear on the battery? But it’s more nuanced - studies show that smart charging and manufacturer battery warranties keep the impact on lifetime small; often the battery stays healthy longer than the car around it.

The RWTH Aachen University study on battery aging shows that after 10 years of use, the additional aging caused by V2G is between 1.7%p** and 5.8%p - while offering EV drivers up to €600 of value each year. You can find all findings of the study in our white paper “Bidirectional charging and its impact on the service life of electric car batteries"

_{** Percentage points}

Many people think that feeding electricity back from the car into the grid (Vehicle-to-Grid) is not permitted by law, at least not in Germany. In reality, however, it is fundamentally possible, but complex from a regulatory perspective. Many EU countries lack clear rules on grid feed-in by vehicles, e.g., on remuneration, billing, or grid security.

Vehicle-to-Home (V2H) and Vehicle-to-Building (V2B) are legally possible, however, as they do not affect the public grid. Countries such as the Netherlands, Denmark, and the UK are considered pioneers with pilot projects and simplified rules.

• United Kingdom:
  Vehicle-to-Grid (V2G) is legally allowed and supported through national programs such as Innovate UK and Ofgem trials. Several energy suppliers already run real-world V2G tariffs using certified chargers from brands like Indra and Wallbox. The system requires registration with the grid operator, but technical and regulatory frameworks are in place.
• Netherlands:
  The Netherlands is one of Europe’s V2G pioneers, with active large-scale deployments in cities like Utrecht using chargers from We Drive Solar and Alfen. National grid operators (e.g., Stedin, Liander) officially permit bidirectional charging under ISO 15118 standards. V2G integration is legally approved and encouraged as part of the country’s smart-grid and renewable-energy strategy.

_{Sources: ElaadNL publishes research report on bidirectional charging, Renault Group Media}

Although doubts about profitability if V2G are often heard, they do not stand up to reality: the savings achieved through V2G are real. In reality, for example, V2H in combination with PV systems can enable self-sufficiency levels of over 80%. With high electricity prices (e.g., >30 ct/kWh), self-consumption management is clearly worthwhile financially.

And: With dynamic electricity tariffs or grid service fees expected in the future, it will become even more attractive. Overall, the benefits depend heavily on driving profile, household load, and tariff structure. As initial commercial applications show, if you plug in your electric car for an average of 14 hours per day and make your vehicle available for bidirectional charging, you can reduce your charging costs to €0.

> Read our press release on this topic

The opposite is true! With the right control system, electric cars can even stabilize the grid, smooth out power peaks, and make better use of renewable energies. Research and practical experience show that large electric fleets can take on many tasks that were previously reserved for conventional power plants.

Example: Days of cloudy weather – hundreds of connected electric cars step in as a “virtual power plant” and help to close supply gaps despite the lull. We already proved that this works in 2028, when a Nissan Leaf was prequalified for the first time in a V2G application as a large power plant in accordance with the guidelines of the transmission system operators, and the electric car was approved for primary control power (PRL).

The larger the fleet, the greater the relief for the grid – and the lower the costs for grid expansion.

Not every home installation is automatically suitable for V2G (Vehicle-to-Grid). The following technical requirements must be met for the integration of a bidirectional wallbox and the feeding of electricity back into the public grid:

• A three-phase house connection with a minimum output of 11 kW is required to safely enable the necessary power flows.
• The domestic power grid must be checked: Especially in older buildings, an electrician should check the wiring, fuses, and protection systems and adjust them if necessary to avoid overload and safety risks.
• The installation of a bidirectional wallbox and all accompanying components (including smart meters and HEMS – Home Energy Management System) must be carried out by a certified electrical contractor.
• Intelligent energy management software or a system for controlling and optimizing energy flows (own consumption, PV use, feed-in) is crucial for efficient V2G.
• A stable internet connection is required for communication between the electric vehicle, wallbox, smart meter, energy management system, and, if applicable, the external power grid.

Apart from the technical framework, it must be noted that, in Germany, the installation must be reported to and approved by the grid operator. A smart meter is required for billing the electricity.