Hager Group and Audi AG present Vehicle to Home, two-way charging from vehicle to home

In the first half of 2020, renewable energies accounted for over 50% of total electricity production in Germany for the first time. But this growing share of green energies is nevertheless accompanied by a fundamental dilemma: they do not always provide electricity when it is needed. Conversely, during sunny days or phases of strong winds, the storage capacity of the energy produced is often lacking. Hager Group and AUDI AG have defined a research strategy that should play a decisive role in solving this problem: bidirectional charging from the vehicle to the home, also called Vehicle to Home (V2H).

The concept is as simple as it is brilliant: the high-voltage battery of an electric car can be recharged by means of the home electric network, but it can also be used as a decentralized storage device for the same network.

"An electric vehicle battery can store a quantity of energy practically equivalent to the needs of an average household for a week", explains Ulrich Reiner, electromobility expert at Hager Group.

This means that in principle any high-voltage battery in electric vehicles can in future be recharged at home using this new recharging infrastructure, but also become a source of energy for the electricity grid.

Homeowners who produce solar energy on their roofs can then store it locally in their vehicle, to return it to the building when needed. This home two-way charging process is called Vehicle to Home (V2H).

According to Ulrich Reiner, “V2H has great potential for savings on the energy bill of property owners. It also makes it possible to reinforce the stability of the electrical network and to offer an emergency power supply in the event of a general blackout ”. He adds : “The idea of ​​using the battery of thousands of electric vehicles in order to fight against global warming motivated us from the start of the project. ".

A technical feat

If the concept seems simple in theory, in practice it requires a strong technological expertise and a very precise orchestration of various technical components. The collaboration between Hager Group and AUDI AG is based on this essential mastery.

Hager Group provides the technical know-how at the heart of the charging infrastructure, which allows the V2H use of the battery of the prototype developed for the Audi e-tron model. Thanks to the E3 / DC subsidiary of the Hager group, whose domestic photovoltaic power plant has seduced the market for many years, the battery can indeed serve as an energy accumulator. However, the proper functioning of a two-way charging system on a daily basis involves other essential elements, such as an intelligent energy management device, in order to ensure the switching between the vehicle and the house according to the sunshine and needs, and finally a charging station. Here too, the Hager Group product portfolio has proven its worth. The American company IoTecha has also contributed to the project to ensure its compliance with the CCS charging standard.

Objective: everyday functionality

The day-to-day functionality of the system was a key criterion for designers from the development phase.

“Access to mobility takes precedence over everything else. Bidirectional recharging must in no way represent a constraint for the customer. ", says Martin Dehm, Technical Project Manager for two-way charging at Audi. “The intelligent charge management system monitors optimal battery usage and thus maximizes the economic efficiency of the entire device. For the customer, the operation is extremely simple: just plug in the vehicle, and the rest is done automatically. "he concludes.

A big step for the energy transition

According to Ulrich Reiner, the relevance of the project is beyond doubt: “In the future, more and more homeowners will have a battery in their basement, garage or outside their home. They will be able to store there, for example, the energy produced by the photovoltaic panels of their house ”. By combining a photovoltaic installation with the domestic storage system and the vehicle battery, households will gain energy self-sufficiency for several days, while relieving the electricity grid. They will thus make a decisive contribution to the energy transition.