Electric vehicles and their charging – in or out? User acceptance of bidirectional charging in Germany

Abstract

An electric vehicles’ battery capacity can be used to store energy and redistribute it to the grid when connected to it. This concept of bidirectional charging is relatively new and has not been introduced widely. Bidirectional charging could be particularly important in times of high grid load. In the present study, it is examined from the perspective of EV users. Their acceptance determines whether bidirectional charging will be introduced and adopted in the future, particularly when charging at home. Through two focus group discussions with EV owners, one with home owners and one with tenants, we identifiy potentials and barriers from a user perspective. Given the design of our focus group discussions, we compare results for home owners and tenants qualitatively. Financial aspects are discussed as an incentive for use but also as a barrier if one needs to invest in new technology. The groups differed in how strongly they wished for governmental support in these issues. Tenants requested incentives for bidirectional charging more strongly. Additionally, acceptance of bidirectional charging was related to its compatibility with daily life, participants were more concerned to employ bidirectional charging when wishing to use their EV spontaneously. One key aspect for all participants was determining a minimum energy level that ought to remain in their vehicle. We find indications that home owners have a more holistic view of their vehicle within the context of their home energy system. As most home owners also had a private photovoltaic (PV-) system, they played a more active role in their own energy system. They also perceived greater personal advantages of bidirectional charging compared to tenants and might even be seen as early adopters. Tenants focussed more on their vehicle and worried about personal disadvantages, e.g. them or their vehicle being impacted negatively by bidirectional charging.