—— Fundamentally reducing the use of fossil energy sources is one of the top global climate goals. One sensible step towards achieving this goal is to optimally utilize energy that has already been produced. Especially in the case of energy produced by photovoltaics, much is lost if it cannot be used immediately and also cannot be stored. Now, after more than a decade of discussion, a possible solution for storage could become more established.

Bidirectional charging is the name of the process when the battery of an electric vehicle, in addition to storing energy, can also feed it back into the grid. For example, a car’s battery can be used to store spare electricity from a photovoltaic system and feed it back into the household network later when needed, for instance if the weather turns cloudy. This can noticeably reduce energy use from the grid and its associated costs.

Many electric vehicles spend more time in the garage than they do out on the streets. While parked at home, they can be used for electricity storage. This concept is known as vehicle to home, or V2H for short, and requires just a minor modification and a special charging plug, a CHAdeMO, to convert the direct current from the battery into alternating current for home use. This process has been successfully established in Japan for years now, while it remains uncharted territory for much of the rest of the world. However, most major carmakers have now signaled that they will equip their vehicles for bidirectional charging in all markets in the future.

THE CAR BECOMES ENERGY STORAGE With the special CHAdeMO charging plug, energy can be fed back into the household grid during idle times.

This will then make the next step possible: V2G, or vehicle-to-grid. The idea here is to integrate as many electric vehicles as possible into the energy grid. The energy stored in the vehicle batteries can thereby be fed back into the general power grid, for instance to help cover peak demand or to take pressure off the grid. There are still no regulatory requirements for this. At the moment, there are also far too few vehicles that are able to charge bidirectionally. Furthermore, the batteries of most of today’s models aren’t designed for an endless number of charging and discharging cycles.

It will still be possible to drive the vehicles, of course. But when they’re parked—and that’s an average of 90 percent of the time—electric vehicles can be used for energy storage. This way, the share of renewable energy in the power grid could be noticeably increased.
However, it is also clear that the idea requires much greater overall planning for mobility solutions. To achieve this, financial incentives for car owners would be necessary. Only then will most people be willing to say: I don’t need my car for a couple of hours, and since I’m just going to get groceries, 15 percent battery power is enough. In other words, a more holistic approach is needed for V2G technology to work.


Getty Images/Lytvynova Alina (general view); Getty Images/petovarga (car, charging);