Comparing ISO 15118 standard compare against OCPP standard.

Comparing ISO 15118 standard compare against OCPP standard

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ISO 15118 and OCPP (Open Charge Point Protocol) are both crucial standards in EV charging infrastructure, but they operate at different levels of the communication chain and serve distinct purposes. Here’s a detailed comparison:

ISO 15118 vs. OCPP – A Comparison

 

Aspect ISO 15118 OCPP (v2.0.1+)
Scope Communication between EV and Charging Station (EVSE) Communication between Charging Station and Backend System (CSMS)
Primary Purpose Enable secure, automated, and intelligent vehicle-grid interaction Enable remote control, monitoring, and billing of charging stations
Security Features – TLS encryption
– Mutual authentication via digital certificates
– Plug & Charge authentication
– Support for PKI		 – TLS encryption
– Certificate-based authentication
– Secure firmware updates
– Event logging & auditing
Communication Model Peer-to-peer (direct between EV and charger) Client-server (charger as client, backend as server)
Authentication Built-in support for Plug & Charge via certificate exchange (PEM/ASN.1 based) Supports external authentication via CSMS; relies on charger’s TLS config
Encryption TLS 1.2 or 1.3 with strong cipher suites TLS 1.2 recommended; some versions support WebSocket security
Protocol Type XML-based protocol over TCP/IP JSON over WebSockets (or SOAP in older versions)
Standard Ownership Maintained by ISO/IEC (international standard) Open standard maintained by Open Charge Alliance
Vehicle-to-Grid (V2G) Fully supports bidirectional energy transfer Not directly involved; relies on ISO 15118 for V2G
Deployment Used in premium EVs and smart charging stations Widely adopted by charging network operators
Complexity High (due to cryptographic and certificate management) Moderate (but increasing with newer versions)

 

Complementary Roles, Not Competing

  • ISO 15118 handles EV-to-EVSE communication, which includes:
    • Secure session initiation
    • Contract authentication (Plug & Charge)
    • Energy management (e.g., smart charging, V2G)
  • OCPP, on the other hand, handles EVSE-to-backend communication, which includes:
    • Remote monitoring and diagnostics
    • Session reporting and transaction management
    • Certificate provisioning and revocation (in v2.0.1)

Together, they form a layered and interoperable architecture. For example, an EV may authenticate with a charger using ISO 15118, and the charger will then report that session via OCPP to the backend system for billing and load balancing.

Sunstreram’s embedded development services group has experience in supporting EV manufacturers and EV charging system manufacturers adapt to these global standards. Talk to our team to discuss how we can support your embedded development needs.