Bidirectional Charging: Potential vs. Reality in EV Energy Storage

Up to €720 per year – that is what BMW and E.ON claimed owners of an iX3 could earn by using their EVs as an energy storage unit, with E.ON paying €0.24 for every hour the iX3 is connected to a bidirectional wallbox. Meanwhile, the traction battery performs exactly as designed: absorbing and releasing electrical energy, depending on market prices. This is how BMW and E.ON aim to generate revenue, with a portion of the profits passed on to the end user.

However, real-world examples of this use case remain extremely rare. BMW has not disclosed sales figures for the iX3, leaving room for speculation: either iX3 drivers are not taking up the offer, or there are underlying difficulties. Unfortunately, such problems would not be surprising. Few aspects of electric cars and trucks exhibit as wide a gap between expectation and implementation as bidirectional charging.

The potential is undeniable: V2G could play a pivotal role in the energy transition and cost recovery. Many players have developed the necessary components, and more car manufacturers are announcing concrete products. Yet, real-world adoption remains limited. So what’s holding it back?

Fragmented standardisation, too few smart meter gateways

“A major breakthrough is still missing,” states Markus Hackmann, Managing Director at the P3 Group, a Stuttgart-based tech consultancy that focuses on e-mobility. According to Hackmann, the “discrepancy between theoretical potential and lived reality” stems from multiple factors. These include fragmented standardisation, the insufficient deployment of intelligent metering systems (Smart Meter Gateways) in Germany, the risk for car manufacturers regarding battery warranties, and the lack of scalable business cases “beyond isolated solutions.”

For example, the share of so-called intelligent metering systems – simplified, digital electricity meters with an internet connection – stands at just 5.5 per cent in Germany, according to the Bundesnetzagentur. This is embarrassingly low compared to the rest of Europe. However, it would be incorrect to pinpoint this as the primary cause. It is the combination of these factors that leads to delays.

Internal competition at Volkswagen

An example of the complexity of this situation lies in the Volkswagen Group. According to reports, VW is pushing bidirectional charging hard behind the scenes. There is no lack of insight; even its EVs, including the new small cars from the Polo to the Skoda Epiq, are V2G-ready.

At the same time, the Group’s commitment appears fragmented. For instance, two of its companies, Elli and Moon, are competing in the bidirectional charging space. Interested parties have been able to register with Elli since the Power2Drive trade fair (DE) if they want to earn up to €720 per year – echoing BMW’s offer. At the same time, Skoda, the current favourite among electric car buyers in the Group, has announced a product with Moon.

Outstanding expertise among German companies

When major brands like BMW or Volkswagen offer a product, agile medium-sized companies often drive progress behind the scenes. Three examples in alphabetical order: Ambibox has developed a DC wallbox produced by Nebula (a part of CATL) and used by Skoda/Moon. EcoG is one of the leading software companies in this space. Meanwhile, at The Mobility House, Supervisory Board Chairman Herbert Diess tirelessly promotes bidirectional charging while also levelling criticism. For instance, Diess describes the structures of distribution system operators as “inefficient and in need of reform” (DE).

Time and time again, though, the issue comes down to money: the fact that the German government’s planned elimination of double grid fees has still not been enacted remains a side note in this context.

An energy transition from the bottom up?

Who benefits from bidirectional charging? This remains a key question. Markus Hackmann of P3, who criticises closed systems, explains: “Today’s solutions often require a specific combination of EVs, wallboxes, and electricity tariffs. While the flexibility of the vehicle is used for grid-supporting applications, the end customer loses much of their freedom in choosing hardware, tariffs, and energy concepts. This high level of provider and technology lock-in contradicts the open and flexible energy systems that V2G is supposed to enable in the long term.”

In other words: we need more bottom-up energy transition.

Multiparty interoperability instead of Proprietary Solutions

Proprietary solutions are a problem. Marco Piffaretti, Operating Agent at Task 53, is well aware of this. Sitting under the International Energy Agency, Task 53 brings together numerous significant and well-known partners from the V2G ecosystem in a consortium. The goal: bidirectional multiparty interoperability.

“The bidirectional charging system cannot currently scale to benefit customers because we lack multiparty interoperability,” says Piffaretti. He explains that proprietary solutions are a drawback that hinders free competition – but standardisation could provide a remedy.

Such standardisation is already in place in China with GB/T, while Japan’s Chademo remains exemplary in this regard. In contrast, 57 out of 186 parameters in ISO 15118-20 (dynamic mode) are still optional in our region. Task 53 aims to eliminate these ambiguities and reduce the total number of parameters to 153. The legal framework for this could be set by the AFIR; national gaps, such as the lack of intelligent metering systems, would need to be addressed by the states themselves.

First profits for high energy volumes and predictability

The many question marks surrounding bidirectional charging make it particularly attractive for customers who combine predictable usage times with high energy volumes – namely, corporate fleets, especially in haulage and logistics.

But what about private customers? Many expect to seamlessly integrate their electric vehicle with existing stationary photovoltaic storage systems. This could happen in the medium term, provided conditions like multiparty interoperability are met. Meanwhile, as part of the broader positive trends in the energy transition, prices for stationary storage systems continue to fall, putting them in competition with mobile storage solutions.

A representative example is the company Ankersolix, which offers an introductory deal for a plug-and-play inverter with five kilowatt-hours of energy capacity at €1,599 or with ten kilowatt-hours at €2,698. These are figures that would have been unthinkable ten years ago – and they are not the end of the downward trend in home storage systems.

There’s work to be done

Returning to bidirectional charging for electric vehicles as participants in the electricity market: what comes next is simply hard work. The many players who have embarked on advancing V2G must persevere in what Bertolt Brecht called “the struggles of the plains” – painstaking, grinding work. It may well take until 2030 for bidirectional charging to truly gain traction. But the foundations are being laid now – and some of them must be fought for.