Bidirectional charging: How an electric car (finally) earns money

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Mercedes and Volkswagen are not amused: BMW supplies a bidirectional wallbox for the iX3 on request, including an electricity contract. In cooperation with E.ON, for the first time in Germany, buyers can get an electric car that becomes a participant in the electricity market. The vision is a reality. What the owners have to do to earn money with the iX3: Plug the charging cable into the suitably equipped wallbox at home and sign a special electricity contract. With this campaign, BMW is putting pressure on the competition, but also on politicians. It is long overdue for the potential of electric cars for the electricity grid to be realised.

The prerequisite for bidirectional charging with the BMW iX3 is the Wallbox Professional, currently priced at 2095 Euro. Unlike most other wallboxes, such as the BMW Wallbox Plus for 699 euros, the system works with direct current rather than alternating current.

Up to 720 Euro per year

According to the press release, a bonus of up to 720 Euro per year is possible, which should be enough for 14,000 kilometers with the e-car. It would therefore be possible to amortise the additional price of the DC wallbox—and more than that in the long term. BMW makes the calculation behind these figures transparent: for every hour that the iX3 is connected to the Wallbox Professional in the electricity contract with E.ON, there are 24 cents. A maximum of 60 euros is possible per month; there is therefore a cap, which corresponds to 720  euros in one year.

To achieve this, the electric car would have to be connected to the wallbox for 3000 of the 8760 hours in a year. With eight hours per night and 365 days per year, this already adds up to 2920 hours; the calculation basis is therefore quite realistic. BMW has used a working price of 32.97 cents per kilowatt hour as a basis. 720 euros are therefore 2184 charged kilowatt hours, which is enough electricity for a good 12,000 to over 14,000 kilometers with a consumption range according to WLTP of 15.1 to 17.9 kWh/100 km. This, in turn, is roughly in the range of the average annual mileage in Germany.

It is unclear how high the monthly basic price is. According to E.ON, this varies from region to region and will only become apparent when the product is actually available to order. Theoretically, there could still be a question mark here. The casual way in which the Bavarian manufacturer mentions this fact is not appropriate: Once the additional costs for the wallbox have been amortized, the electric car drives free of charge for the average German.

Durability: no restrictions

BMW guarantees that the “high-voltage battery is always kept at an optimum level for its service life” and that this is not impaired. Translated, this probably means that a charging window is used that is not too far away from the ideal level of 50 percent. The owner can also specify when they want to start and with how much range. The long-term plan is to “integrate the product into a holistic energy platform that intelligently connects charging infrastructure, photovoltaics, heat pumps, and smart home systems.” Of course, everyone wants that. BMW is making a start.

Volkswagen shows pilot project

The fact that the other German car manufacturers, Mercedes and Volkswagen, are not the first to offer such a service has reportedly caused resentment. Both are not idle. Volkswagen presented a pilot project at the IAA with its own company Elli, which enables bidirectional charging. Mercedes has announced a cooperation with The Mobility House for the GLC EQ.

Ambibox from Mainz is another agile company in the market for bidirectional wallboxes. The Ambicharge wallbox can be pre-ordered now and will be delivered from 2026. Before then, 500 wallboxes will be sent to partner companies for extensive testing. Ambibox sees V2X (for Vehicle to X)-capable wallboxes in several areas of application. The most prominent is what BMW is doing with E.ON, namely the electric car as a participant in the electricity market. Charging when the market price is low and vice versa.

The electric car as a storage extension

In addition, and of particular interest to many private customers, is the prospect of expanding an existing storage system for electricity from their own PV system with the electric car. A bidirectional wallbox for this purpose could be connected either to the home grid (AC) or directly to the home storage system (DC). Home storage systems are an important element in increasing the self-consumption rate for solar power. If an electric car offers additional kilowatt hours, that would be a great advantage.