The automotive industry is transitioning to electric vehicles (EVs), creating a higher electricity demand. Concurrently, the utility sector is shifting to a renewable energy system. Vehicle-to-grid (V2G) technology allows EVs to both consume and deliver electricity to the grid, introducing a dynamic interaction. However, integrating EVs into the grid raises challenges related to grid safety, such as the risk of overloading. To address this, additional technical specifications are needed. The EV charging industry relies greatly on international standards. Therefore, market players seek clear guidelines for products enabling bidirectional power flows. However, technical requirements specific to V2G systems remain unspecified or divergent, creating obstacles for technology development and implementation by the industry. Harmonisation and standardisation of technical specifications are considered effective means for overcoming these challenges. However, existing literature lacks insights into the necessity and realisation of harmonisation. This study fills this gap by exploring the extent, reasons, and coordination efforts required for harmonisation of technical requirements specific to V2G. Particularly, this study investigates barriers stemming from the technical implementation of V2G and their impact on the adoption by key stakeholders.

An open-minded approach following the grounded theory principles identified primary obstacles in the technical implementation of V2G. The grounded theory approach included conducting semi-structured interviews with ten participants, which helped explore perspectives and needs of five key stakeholder groups. In addition, a comprehensive framework is consulted to provide a theoretical lens assisting the interpretation and analysis of the empirical results. Integrating the widely adopted Institutional Analysis & Development (IAD) framework and Multi-Level Perspective (MLP) aided in identifying and understanding the interplay between institutional arrangements, such as technical requirements and standards, and technology adoption. This novel approach has proven to be valuable in analysing the relationships between micro-level interactions (IAD) and macro-level influences (MLP).

This study has shown it is unclear to niche actors how to become "V2G-ready" due to a lack of clear guidelines, especially related to the charging standard (AC or DC), the communication standard between system operators (DSOs) and charge point operators (CPOs), grid connection codes, and who should be in control of discharging schedules. Requirements deficiency and disparities and the discussion on the control authority show constraining effects on the conditions for pilot projects. Realistic pilot conditions are shown to be essential for scaling V2G activities, and pilot projects are considered vital for exploring the possibilities of V2G technology. However, lacking conditions obstruct the development of definitive V2G configurations and designs necessary for large-scale diffusion. This study has shown two chicken-and-egg dilemmas play a significant role in the slow adoption of V2G. Niche actors are awaiting each other to continue their research and development activities. EV manufacturers demand V2G-compatible EV supply equipment (EVSE) to experiment with V2G technology, while EVSE manufacturers and CPOs await V2G-compatible EVs. Moreover, niche actors await definitive technical standards, while standardisation organisations and regulators are reliant on insights retrieved from practical experimentation to develop effective standards and regulations. These dynamics require a coordinated approach to empower and stabilise the development of V2G technology and enable widespread diffusion. Niche actors should be at the front of the developments, so active involvement with standardisation and requirement-setting is advised. Besides, collaborations between niche actors across Europe should be stimulated to prevent market fragmentation and segmentation, since these effects are detrimental to all V2G actors and the system in general. Therefore, the barriers identified pose a significant influence on pilot conditions, constraining experimentation, implementation, and the overall development of V2G technology.