ISO 15118 is an international standard series for vehicle-to-grid communication between an electric vehicle (EV) and charging equipment (EVSE). It defines a secure, standardized way for the car and charger to exchange information for smart charging, Plug & Charge, and (in newer parts) bidirectional energy transfer use cases like V2G.
What Is ISO 15118?
ISO 15118 specifies the “language” used between the EV and charger for:
– Session setup and negotiation (what power, what limits, what connector)
– Charging control (start/stop, power requests, constraints)
– Identification and authorization (including certificate-based methods)
– Secure communication using cryptography and certificates
It is most commonly associated with CCS-based charging environments and higher-level EV↔charger communication beyond basic control pilot signaling.
Why ISO 15118 Matters in EV Charging
ISO 15118 enables higher-value charging features that improve user experience and operational scalability:
– Plug & Charge: automatic authentication when you plug in (no app/RFID at the charger)
– Smart charging: structured data exchange that supports optimized charging behavior
– Future grid integration: a pathway toward controlled, bidirectional energy use cases where supported
Plug & Charge
Plug & Charge (PnC) uses digital certificates so the vehicle can authenticate to the charging station automatically:
– The EV presents a certificate-based identity
– The charger validates it and authorizes charging
– Billing can be linked to the contract behind that identity
In practice, Plug & Charge depends on PKI, certificate provisioning, and strong credential management across OEMs, operators, and platforms.
ISO 15118-2 vs ISO 15118-20
ISO 15118 is a series with different parts:
– ISO 15118-2 defines network and application protocol requirements for EV-to-EVSE communication (commonly referenced for Plug & Charge and smart charging message sets).
– ISO 15118-20 expands and modernizes the framework and is widely referenced in the context of bidirectional charging and broader use cases (including newer charging scenarios).
ISO 15118 and Bidirectional Charging
Bidirectional charging (e.g., V2G, V2B, V2H) requires controlled two-way power flow plus secure communication and authorization. ISO 15118-20 is commonly cited as the key communication standard enabling these bidirectional interactions at the protocol level (where vehicles, chargers, and regulations support it).
Operational Considerations
Implementing ISO 15118 features typically introduces additional requirements:
– Certificate lifecycle and PKI processes (issuance, rotation, revocation)
– Strong device and platform security (secure key storage, controlled provisioning)
– Backend readiness to support Plug & Charge contracts and session handling (often alongside OCPP for charger-to-backend operations)
Related Glossary Terms
Plug & Charge
ISO 15118-2
ISO 15118-20
Vehicle-to-Grid (V2G)
Public Key Infrastructure (PKI)
Certificate Management
OCPP
Smart Charging
Interoperability
Cybersecurity