Since its release in 2020, OCPP 2.0.1 has gained significant attention and is now used to manage charging stations on the field. To address the evolving needs of the electromobility ecosystem, the Open Charge Alliance has been working on a new version of OCPP, OCPP 2.1, released in January 2025.

In a nutshell, OCPP 2.1 introduces several key updates, including support for bidirectional charging (with native integration of ISO 15118-20 and CHAdeMO), grid code management, enhanced payment options (prepaid cards, credit cards, QR codes), expanded smart charging, improved transaction management, and a range of other improvements based on feedback from the EV charging community.

As a contributor to this new version of the protocol, we will summarize its new features and analyze the impact on existing OCPP 2.0.1 implementations.

Retrocompatibility as a guideline

The guiding principle for OCPP 2.1 is retrocompatibility. This ensures that implementations built on OCPP 2.0.1 will continue to function in OCPP 2.1, facilitating the deployment of the new version. The new features are introduced through dedicated use cases that involve new messages and/or existing messages with additional optional fields.

To select a compatible version between the Charging Station (CS) and the Charging Station Management System (CSMS), the CSMS will choose the version(s) specified in the WebSocket header sent by the charging station.

Native integration of bidirectional charging

One of the most significant updates in OCPP 2.1 is the native support for ISO 15118-20, enabling smart charging and smart discharging. ISO 15118-20, the standard for EV <-> EVSE communication that brings bidirectional functionalities, was released in 2022. It was  not supported in OCPP 2.0.1. This is now the case in OCPP 2.1!  It includes the implementation of charging and discharging schedules, one additional charge control mode ( Dynamic, where the charging station has full control over the power drawn by the EV). With these additions, a CSMS can monitor and control bidirectional charging sessions, enabling energy services such as triggering energy injection into the grid.

Grid code management

A grid code is a technical specification which defines the parameters a facility connected to a public electric grid has to meet to ensure a safe, secure and economic functioning of the electric system. 

As the number of charging stations increases, their role as critical components of the grid grows. Charging stations are now considered as Distributed Energy Resources (DER) by utilities. A DER is a generation unit distributed on the grid such as solar PV, battery storage, or charging stations. This means that the charging system (the charging station connected to an EV) has to comply with the local grid regulation. For example, a charging station connected to the Dutch grid shall apply the Dutch regulation. If the station is connected  to the French grid, it shall apply the French regulation which is different from the Dutch one. So the grid codes need to be configurable on the charging station to adapt to the different regulations. OCPP 2.1 then provides a way to configure them on the charging station with the CPO acting as an intermediary between the charging station and the utility (DSO, TSO, aggregator, ..).

The application of these DER controls differs between AC and DC charging:

  • For DC charging, the inverter is part of the charging station, making it responsible for applying the controls. These controls are typically static since the location of the charger is fixed.
  • For AC charging, the inverter is located in the vehicle, so it is the vehicle’s responsibility to apply the controls. However, since the EV does not receive grid codes directly from the utility, the charging station is a mean to transmit them to the vehicle to avoid latency. This capability is not supported by the current version of ISO 15118-20, which is why an amendment to the standard is being discussed. OCA has been working closely with the ISO Technical Committee to ensure OCPP 2.1 remains compatible with this future amendment.

Adhoc payments

OCPP 2.1 has expanded its payment options to improve user experience, adapt to country-specific requirements, and enhance security. The new payment features include:

  • Credit card terminals: This allows users to pay directly at the charging station using credit or debit cards. For this to work, the payment terminal must be connected to the CSMS, though this connection is outside the scope of OCPP.
  • Prepaid charge cards
  • Dynamic QR codes: To enhance the security of QR code-based payments, the CSMS can now provide a URL for the driver. This allows the CSMS to validate the information and prevent QR code spoofing.

Local Energy Management

A charging station can receive energy constraints from different sources (CSMS, Local EMS, Grid, …) and different protocols (OCPP, Modbus, …). An EMS can regulate the power delivered by the charging stations using different means:

  • direct connection with the charging station 
  • transmit information via the CSMS
  • transmit information via a local controller

To efficiently manage these energy flows, an EMS plays a critical role in regulating the power delivered to the charging stations. To integrate this complexity into the systems, OCPP 2.1 outlines the architecture and possible scenarios for how charging stations shall report energy constraints back to the CSMS. This includes specifying the source of the constraints, whether they are coming from the grid, local EMS, or other external sources. 

Other new features: 

Finally, this new version of OCPP contains new use cases to answer the current and upcoming ecosystem expectations:

  • Priority charging: The CSMS can configure the charging station to charge an EV with the highest possible power and avoid discharging the vehicle. The priority can also be configured on the charging station by the driver so the charging station shall inform the CSMS.
  • Battery swapping: Battery swapping is the process whereby an EV driver exchanges the near empty EV battery for a charged EV battery. The returned battery is placed in a dock and then charged again. Once it reaches a certain level of state of charge it becomes eligible to be swapped again for an empty battery. Mechanisms are described to monitor the battery state in the station (SoC, availability for drivers), to record the swapping operations, etc.

Trialog’s expertise:

Trialog recognizes the importance of OCPP and the critical role it plays in the development and deployment of EV charging infrastructure. Trialog is deeply involved in the development of OCPP and committed to streamline its implementation process. As active members of the Open Charge Alliance, we have made significant contributions to the certification process, the validation of the OCPP Certification Testing Tool (OCTT) and the development of OCPP 2.1. Collaborating with other industry leaders, we actively shape the future of EV charging infrastructure. Our participation in OCPP development has provided us with unparalleled expertise, enabling us to assist businesses in navigating the complexities of this rapidly evolving landscape.

To this end, we offer a comprehensive OCPP software stack for both Charging Stations (CS) and Charging Station Management Systems (CSMS) implementing OCPP 1.6, 2.0.1 and early implementation of OCPP 2.1. Our software products for CSO and manufacturers are designed to help businesses easily integrate OCPP into their charging infrastructure, reducing development time and ensuring interoperability.

In addition to our software solutions, we offer two useful products designed to assist in validating and troubleshooting their OCPP implementations: EVSE ComboCS and OCPPvs (OCPP Virtual Stations). The EVSE ComboCS serves as a physical charging station simulator with integrated OCPP capability, ideal for businesses requiring a device that can communicate using both OCPP and ISO15118/DIN70121. On the other hand, OCPPvs is an innovative product that allows businesses to test their energy management systems by simulating numerous virtual EVs and charging stations. It can also be used for debugging and validating OCPP implementation against a virtual charging station and EV. OCPPvs provides businesses with a testing environment that closely mirrors real-world scenarios, enabling them to simulate and replicate various use cases effectively.

 

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