ISO 15118-20:2022

Overview

ISO 15118-20:2022 - Road vehicles: Vehicle-to-grid (V2G) communication interface - Part 20 defines the second‑generation network and application layer requirements for communication between an electric vehicle (EV: BEV/PHEV) and electric vehicle supply equipment (EVSE). Published as part of the ISO/IEC collaboration, the standard specifies IP‑based messaging, session handling and sequences designed to support electricity transfer (including bidirectional power transfer / V2G) and information services for charging status and control.

Key topics and technical requirements

• Scope and roles: Defines interfaces between the Electric Vehicle Communication Controller (EVCC) and the Supply Equipment Communication Controller (SECC).
• Application layer messages & sequences: Formal message definitions, handshake, service selection, message sequencing, error handling and timing for AC/DC and wireless charging.
• Network & transport stacks: IP‑based communication with specified use of transport protocols (TCP, UDP) and the V2G transfer protocol for payloads.
• Security and certificates: TLS use, certificate/key management, root certificate validity, cryptographic key protection, random number generation and firewall considerations.
• Data link & wireless: Requirements for conductive (including WLAN) and wireless power transfer (WPT) communication, and handling of Automatic Connection Device (ACD).
• Presentation & encoding: XML and Efficient XML Interchange (EXI) usage, message headers, PDU structures and message security mechanisms.
• Normative artifacts: Schemas, certificate profiles and identifier specifications; informative annexes on sequence examples, interoperability and precision/tolerances.

Practical applications

• Enables standardized, interoperable smart charging and vehicle‑to‑grid use cases: controlled charging, demand response, and V2G discharging back to the grid.
• Supports wireless charging (WPT) control and automatic connection devices, as well as value‑added information services (billing, session status, diagnostics).
• Provides the protocol foundation for charging station firmware, EV telematics stacks, backend charging management systems and utility/grid integration.

Who should use this standard

• EV and EVSE manufacturers (hardware & firmware)
• Charging network operators and roaming/service providers
• Software developers of EV charging stacks, telematics and back‑end platforms
• Utilities, grid operators and energy service companies implementing V2G services
• Test laboratories and certification bodies verifying protocol and security conformance

Related standards

• ISO 15118 series (other parts)
• IEC 61851‑1 (EV conductive charging) - referenced for signalling synchronization
• IEC 61980‑2 (wireless power transfer for EVs) - referenced for WPT signalling

Keywords: ISO 15118-20, vehicle-to-grid, V2G communication, EVSE, EVCC, SECC, bidirectional charging, EV charging protocol, wireless charging, EXI, TLS, IP-based EV charging.