1. Overview and development history of OCPP protocol
1. Protocol Definition and Core Objectives
The Open Charge Point Protocol (OCPP) is a standardized communication protocol developed by the Open Charge Alliance (OCA) to solve the interoperability issues between electric vehicle charging equipment (EVSE) and central management system (CSMS). Its core goals include:
- Equipment compatibility : Allow charging piles from different manufacturers to seamlessly connect with the backend system, reducing operator procurement restrictions
- Functional scalability : modular design supports value-added functions such as smart charging and remote diagnosis
- Network scalability : Providing a unified technical framework for the construction of cross-border charging networks, such as the IONITY European high-speed charging network
2. Version evolution and key updates
OCPP 1.5 protocol(2012 )
The first officially released standard version uses SOAP/XML communication and defines basic charging control (such as StartTransaction, StopTransaction) and status monitoring (Heartbeat, StatusNotification). However, due to the lack of strict testing specifications, there are compatibility differences among different manufacturers.
OCPP 1.6 protocol(2016 )
OCPP1.6 is a milestone update for electric vehicle chargers. It not only improves the compatibility issues of the OCPP 1.5 protocol, but also adds three core extensions:
- Smart Charging : Supports dynamic power adjustment based on electricity price or grid load (via SetChargingProfile command)
- Firmware Management : Implement OTA firmware upgrade (UpdateFirmware/FirmwareStatusNotification)
- Reservation : Charging station reservation function to improve user efficiency
Due to its flexible functions and scalability, this version has gradually become the mainstream in the industry. Currently, more than 80% of public charging piles in the world support the OCPP 1.6 protocol.
OCPP 2.0.1 protocol(2020-2023 )
Based on OCPP 1.6, a revolutionary upgrade has been achieved, with the following main features:
- Bidirectional charging support : Integrate ISO 15118 standard to achieve vehicle-to-grid (V2G) energy feedback
- Enhanced security mechanism : mandatory use of TLS 1.2 encryption (Profile 2), support for client certificate authentication (Profile 3)
- Device management optimization : Added GetLog, SignCertificate and other instructions to meet the compliance requirements of the EU RED Directive
- Test standardization : The third edition (2023) improves test cases and increases the certification pass rate by 40%
However, due to the new version, there are many compatibility issues with the electric vehicle charging piles equipped with the OCPP 1.6 protocol, so it has not yet achieved wide coverage. For example, ChargePoint charging piles may not support the reservation function expansion of third-party CSMS.
2. OCPP Technical Architecture and Core Modules
1. Functional module division
| Module Type | Core instruction examples | Application Scenario |
| Basic Control | StartTransaction, StopTransaction | Charging start and stop, user identity verification (RFID/App) |
| Billing and metering | MeterValues, CostUpdated | Real-time billing, time-of-use electricity price calculation |
| Smart Charging | SetChargingProfile, ClearedChargingProfile | Grid load balancing and photovoltaic consumption optimization |
| Device Management | UpdateFirmware, GetDiagnostics | Remote maintenance, fault diagnosis |
2. Communication mechanism and protocol stack
- Transport layer protocol
- WebSocket (mainstream solution) : full-duplex communication, support for real-time status push (such as StatusNotification), latency less than 500ms
- SOAP/XML (old version compatible) : Based on HTTP long polling, high data redundancy (JSON volume is reduced by about 60%)
- Security Configuration
| Profile | Authentication | Applicable scenarios |
| 0 | No encryption | Test environment |
| 1 | HTTP Basic Auth | Internal Network |
| 2 | TLS 1.2+ one-way certificates | Public network (default recommendation) |
| 3 | TLS 1.3+ mutual certificates | Financial-grade high-security scenarios |
Data format optimization : OCPP 1.6+ uses JSON instead of XML, and the data size of a single instruction is reduced from 2KB to 0.8KB, significantly reducing network bandwidth consumption.
III. Certification system and compliance requirements
1. Comparison of certification types
| Certification Type | Test range | Target customers |
| Fully certified | All core + extended features (such as V2G) | High-end commercial charging pile |
| Subset Authentication | Basic control + metering | Entry-level AC charging pile |
| Safety Special Certification | TLS configuration, certificate chain verification | Financial/Government Project Procurement |
2. Certification process example
- Pre-test : Verify basic communication using OCPP Test Tool
- Laboratory testing : 3000+ test cases (such as charging plug-in interruption recovery test) performed in OCA authorized laboratories
- On-site audit : Check the log storage policy in the production environment (original data must be retained for more than 6 months)
IV. Application Scenarios and Future Trends
1. Smart charging optimization case
- Peak shaving and valley filling strategy : A European operator dynamically adjusts the charging power through SetChargingProfile of OCPP 1.6, reducing 150kW fast charging to 50kW during peak hours of the power grid, reducing demand electricity charges by 30%.
- V2G business model : Nissan Leaf uses OCPP 2.0.1+ISO 15118 to store energy during low electricity price periods and sell electricity back to the grid during peak periods, with an average annual profit of €120 for users.
2. Security threats and responses
- Man-in-the-middle attack (MITM ) : A third-party charging station leaked user credit card information because TLS was not enabled
- Firmware tampering : Malicious firmware can implant mining programs through the UpdateFirmware command
This article progresses from the underlying mechanism of the protocol to commercial applications, providing a full-view technical reference for charging pile manufacturers, energy operators and standard setters. With the popularization of the OCPP 2.0.1 protocol, the electric vehicle charging network will accelerate its evolution towards an intelligent and highly secure energy Internet node.
