Get a quick and up-to-date overview of the developments in the field of intelligent building technology. The content is customizable to your interests, presented in a neutral manner, and created by experts for experts.
Bidirectional charging has long been technically feasible. But what obstacles are slowing down a solution that could make both buildings and power grids more resilient while driving the energy transition forward?
Can electric cars accelerate the energy transition?
Photo: AleaIL
Could electric vehicles speed up the shift to renewables? And could they also solve the challenge of stabilising the fluctuating supply of electricity from wind and solar?
In Germany, the concept of bidirektionales Laden (EN: bidirectional charging) is still relatively unknown, even though the BDL Next project in Munich has already shown that it can be used in everyday life. Imagine a power outage: the lights stay on, devices keep running – not because an emergency generator kicks in, but because the car supplies electricity back into the house.
The principle of bidirectional charging: electricity doesn’t just flow from the grid into the battery, but also back again – into the home (Vehicle-to-Home, V2H), into the wider grid (Vehicle-to-Grid, V2G), or into building infrastructures (Vehicle-to-Building, V2B). With cars parked around 95% of the time, they represent an immense and largely untapped storage resource.
Business opportunities for fleets and companies
Photo: Ralph Hahn
“The core idea is that we want to stabilise the grids using renewable energy from wind and solar power, and bidirectional charging. In order for that to work, the technology must be highly reliable,” explains Luca Husemann, a research assistant on the BiFLex-Industrie project at the University of Duisburg-Essen.
Companies with larger fleets stand to benefit the most. Vehicles parked for extended periods could be used to balance peak loads, reduce electricity costs, and increase the share of self-consumed solar energy.
David Meyer, project manager of the BiFlex-Industrie research project, also sees huge potential but highlights the hurdles: “Currently, a bidirectional wallbox costs around 4,000 euros. However, depending on the application, savings or revenues of between 200 and 800 euros per vehicle per year can be achieved. This is, of course, still a major obstacle for companies,” he says.
International frontrunners, German challenges
Countries like Japan, California (US) and China are already much further ahead in integrating bidirectional charging into their energy strategies. Germany, by contrast, is struggling with unclear responsibilities, regulatory issues and the lack of standardised billing models.
Although ISO 15118-20 provides a communication standard, it is not yet binding or fully implemented. This, combined with different infrastructure approaches and legal uncertainties, continues to slow down development.
“Bidirectional charging can only be scaled up when it is clear who is responsible for what and how billing will be handled.”
From niche to standard
For bidirectional charging to gain momentum in Germany, technical readiness is not enough. What is needed are uniform standards, clear regulation, targeted incentives and investment in infrastructure. Another major barrier is taxation: mobile storage devices are taxed twice – once when charging and again when supplying electricity back to the grid.
At the same time, initiatives such as the Coalition of the Willing on Bidirectional Charging are working on European standards. Building user trust will also be critical, so that consumers feel their participation makes sense and pays off.
The example of Uwe Möller, a private test user in the BDL Next project, shows what’s possible. His BMW i3 is usually parked during the day and charges itself with solar power from his roof. In the evening, when electricity is expensive, it feeds energy back into the house. “Not only do I save money,” says Möller, “but I also feel like I’m part of an intelligent system.”
The technology is ready. What is still missing are clear political decisions, reliable regulations and trust from users – so that electric cars as batteries can move from niche to mainstream.
“Despite the standardised data interface between the vehicle and the bidirectional charging station, problems arise because the standard has not yet been fully implemented in some cases, or because it does not include all the necessary data.”
