User acceptance of bidirectional charging as a decisive key in global automotive competition

Abstract:

Bidirectional charging is a technology that is becoming increasingly relevant in the automotive industry and could become a decisive competitive advantage in global automotive competition (Wouters and Martinez, 2024). Numerous research projects are being implemented internationally to ensure the rapid realisation of this technology (Vollmuth et al., 2024). However, this technology is not only a decisive key in the automotive industry, but also in the energy sector and can increase the economic efficiency of battery electric vehicles on the one hand and promote the increasing spread of renewable, sustainable energies on the other (Thompson and Perez, 2020). The utilisation potential of vehicle batteries is huge. On average, vehicles spend 95 to 97% of their time parked (Brandt et al., 2017). The utilisation time of the vehicles and the batteries in particular can be increased by charging and discharging the batteries during the parking time. The large storage capacity of the batteries that is thus available can be utilised for a wide range of applications (Leippi et al., 2024). A closer analysis of this idle time shows that the vehicles remain at home or at work (Destatis, 2021). At the workplace in particular, the capacity of the batteries from employee and company vehicles can be used directly in the company, e.g. to optimise self-consumption or for energy trading (Kubli, 2022).

However, a decisive basis for the introduction of such a new technology is the acceptance of the users (Kraus et al., 2023). Employees must be willing to make their vehicles available for bidirectional charging (Noel et al., 2021). Due to the additional charging and discharging cycles in bidirectional charging, concerns regarding the limited range or additional battery degradation are to be expected (Huang et al., 2021). In addition, users of bidirectional charging are often offered financial compensation that would increase their willingness-to-accept in the face of usage restrictions and battery aging (Lee et al., 2020). It is also interesting to see what differences there are, for example, between owners of electric vehicles or internal combustion vehicles, or between private cars and company cars. Income, age or education could also have an influence on the acceptance of bidirectional charging and should therefore be analysed. The literature to date remains general regarding user acceptance of bidirectional charging and does not examine the specific use case in the workplace, which will, however, become increasingly important in the future.

The research question therefore arises: What aspects influence employees' acceptance of providing their vehicles for bidirectional charging at the workplace and how does this acceptance depend on socio-demographic factors or previous vehicle use?

To answer this research question, more than 700 employees from various companies were surveyed using a choice-based conjoint analysis. The users were given a choice between three option packages, each with five varying attributes, such as battery aging, mandatory plug-in time or remuneration model. These attributes and the respective attribute levels were in turn derived from a systematic literature analysis. In addition, socio-demographic aspects and previous vehicle use were queried. With the help of the Sawtooth software, it was possible to derive from the survey results which attributes are of particular importance to users of bidirectional charging. In addition, further correlation and difference tests using SPSS software provided information on the correlations between acceptance and the previously used drive train or the type of vehicle financing.

For users of bidirectional charging, the additional battery aging, the mandatory plug-in time and the guaranteed minimum range are of particular importance. As expected, low battery aging, a high guaranteed driving range and a low plug-in time obligation are accepted. The study also found, for example, that the length of the journey to work correlates with the importance of the minimum range and that users of leasing vehicles consider the aging of the battery to be less important than cash buyers. In addition, the results of the study can be used to quantify the minimum remuneration and the minimum driving range expected by users.

This study therefore provides valuable insights into the implementation of bidirectional charging. Although technology offers great potential in principle, it must also be accepted by the users or owners of the vehicles. Based on the results of this study, specific, user-friendly offers can be implemented to ensure a high level of user acceptance. This study therefore also represents a preliminary study for the development of business models (e. g. Teece, 2010) in the context of bidirectional charging.
 
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