Bidirectional charging dominates next development step for EVs – German engineers

Electric vehicles (EVs) should not only be seen as a transformation technology in the transport sector but also become a key element for the planning of electricity infrastructure by using their batteries as storage units, electrical engineering association VDE has said. Bidirectional charging and interconnection technology mean that EVs could become “active parts of a smart and renewable energy system,” the association said. 

The public debate in Germany is often reduced to competitiveness in the automotive sector, the cost of EVs, or their climate impact, VDE said. “This perspective is shortsighted.” Car batteries in future could do much more than simply propelling cars and instead absorb excess output from wind and solar power installations to curb grid load and feed electricity back into the network or to buildings when demand increases. 

“The next step in electric mobility is not bigger batteries but rather smart interconnection of vehicles, charging infrastructure and the electricity system,” said VDE mobility director Ralf Petri. Bidirectional charging technology allows making EVs flexible storage units that help to better integrate renewables, Petri said. “This is where value is created for customers, companies and the energy transition.”  

The engineering association has launched two research projects with funding from Germany’s economy ministry that look at the role EV batteries can play in transforming the energy system. One project examines the opportunities for companies to use their vehicle fleets and explore possible new business options, while a second one looks into using charging and battery status data for better predicting and marketing electricity flows. 

“To turn bidirectional charging from a pilot project into a mass market, internationally standardised norms and uninterrupted interoperability along the entire value creation chain are needed,” VDE said. The challenge would lie in making EVs, charging infrastructure, energy systems and energy markets work together, for which agreed standards are a prerequisite. “Germany and Europe have a particular strength when it comes to standard setting, interoperability and cybersecurity. These competencies will decide the next development step of electric mobility,” Petri said. 

While bidirectional charging is already technically feasible, it is not yet widespread due to several unresolved factors, energy industry association BDEW said earlier this year. Besides the lack of international industry standards for vehicles and charging points, this includes questions regarding the taxation of power use and marketing, when EV owners feed their electricity into the grid. Another hurdle in Germany is the lagging rollout of smart meters, as the technology requires adequate measuring and billing systems to allow a bidirectional charging market to function.