OCPP Protocol

Overview

The Open Charge Point Protocol (OCPP) is an application protocol for communication between Electric Vehicle (EV) charging stations and a central management system, also known as a Charging Station Management System (CSMS). It was developed by the Open Charge Alliance (OCA), a global consortium of public and private EV infrastructure leaders.

OCPP enables charging station operators to connect their stations to a central system regardless of the vendor, allowing for vendor-independent charging networks. This open standard promotes interoperability and flexibility in EV charging infrastructure.

OCPP Message Structure

OCPP 2.0.1 uses JSON over WebSocket for communication. Each message consists of a message type identifier, a unique ID, an action name, and a payload. Here's the general structure:

[MessageTypeId, UniqueId, Action, Payload]

Where:

• MessageTypeId: 2 for request, 3 for response, 4 for error
• UniqueId: A unique identifier for the message
• Action: The name of the action (for requests) or empty (for responses)
• Payload: The JSON payload containing the message data

[2, "19223201", "BootNotification", {
  "reason": "PowerUp",
  "chargingStation": {
    "model": "SingleSocketCharger",
    "vendorName": "VendorX",
    "serialNumber": "123456",
    "firmwareVersion": "1.0.1"
  }
}]

[3, "19223201", {
  "status": "Accepted",
  "currentTime": "2023-05-06T10:00:00.000Z",
  "interval": 300
}]

Smart Charging

One of the key features of OCPP is smart charging, which allows for dynamic control of the charging process based on various factors such as grid capacity, energy prices, and user preferences. OCPP 2.0.1 provides enhanced smart charging capabilities through charging profiles.

Charging Profiles

Charging profiles define how much power a charging station can deliver over time. They can be set for specific transactions, EVSEs, or the entire charging station. Here are the key components of smart charging in OCPP:

• ChargingProfiles: Define charging profiles to control power consumption
• SetChargingProfile: Set a charging profile for a specific transaction
• ClearChargingProfile: Clear a charging profile
• GetCompositeSchedule: Get the composite charging schedule for an EVSE

Implementation Considerations

When implementing OCPP in your EV charging infrastructure, consider the following best practices:

Choosing the Right Version

While OCPP 2.0.1 offers more features and better security, OCPP 1.6 is still widely used and has broader support in existing charging stations. Consider your specific requirements, compatibility with existing systems, and future needs when selecting an OCPP version.

Security Implementation

Always implement proper security measures:

• Use TLS 1.2 or higher for all communications
• Implement strong authentication mechanisms
• Validate all inputs to prevent injection attacks
• Keep firmware and software up to date
• Use client certificates for charging station authentication when possible
• Implement proper access control for administrative functions

Testing and Certification

The Open Charge Alliance provides a certification program for OCPP implementations. Getting your implementation certified ensures compatibility with other OCPP-compliant systems and helps identify potential issues.

Monitoring and Logging

Implement comprehensive logging and monitoring for your OCPP communications to help troubleshoot issues and detect potential security breaches.

OCPP vs. Other Protocols

OCPP focuses on the communication between charging stations and management systems, while other protocols serve different purposes in the EV charging ecosystem: