Vehicle-to-Grid (V2G) technology, which enables bidirectional energy flow between electric vehicles (EVs) and the public power grid or domestic grid, holds significant potential for enhancing grid stability, improving renewable energy integration, and offering economic incentives to EV owners. However, the lack of a standardized and interoperable system architecture has become a major barrier to its efficient implementation. This paper addresses the pressing need for a unified V2G system architecture by focusing on essential interfaces and proposes a structured approach to achieve comprehensive interoperability due to an overall perspective.

Our methodology begins with a detailed analysis of the entire V2G chain of effects, examining individual components and evaluating each interface's capability to support bidirectional charging. By questioning these elements, we identify critical interoperability requirements that inform the architectural framework. Next, we undertake a systematic consolidation of existing V2G architectures to ensure their adaptability to various behind-the-meter (BTM) configurations and enhance their compatibility with evolving V2G applications. This consolidation process lays the groundwork for a robust and adaptable architecture that integrates various devices, systems and communication protocols.

In parallel, we map ongoing standardization efforts relevant to the mapped interfaces, highlighting the progress of protocols such as ISO 15118-20, IEC 61850 and Open Charge Point Protocol (OCPP) while identifying areas for improvement specific to BTM applications. We assess these standards’ competency for supporting bidirectional charging within the V2G context, critically evaluating their strengths and limitations. This analysis reveals standardization gaps that must be addressed to support the scalability and flexibility of V2G systems across different markets and regulatory environments.

Additionally, our study identifies barriers arising from data gaps that limit V2G’s effectiveness in flexibility marketing. To address these hurdles, we propose adaptations concerning the frequency and the technical realization of data exchange, as well as the accuracy of measurements, that improve communication consistency and support a flexible and responsive energy market. By addressing data-related limitations, we enable more accurate demand forecasting and a dynamic response to grid fluctuations, thereby enhancing the V2G system’s overall performance.

This paper provides a comprehensive framework for developing a unified, BTM-inclusive V2G architecture. Through systematic interface testing, standard mapping, competency assessment, and data adaptation, we lay a foundation for an interoperable V2G ecosystem that meets the demands of both current and future energy systems.