E-MobilityOpen Standards

Open Standards for EV Charging - Open InterCharge Protocol


Bartłomiej Łazarczyk



Open intercharge protocol for ev charging
Open standards for EV charging

Open Intercharge Protocol - background

OICP is developed and owned by Hubject (a joint venture of the BMW Group, Bosch, Daimler, EnBW, Innogy, Siemens and the Volkswagen Group). Initiated in 2012, Hubject is now the largest pool of charging stations. Via Intercharge they provide standardized access to eMobility infrastructure through their dedicated platform. They also advise on how to best implement Plug&Charge with ISO15118 standard.

Hubject has created the largest global charging network for electric vehicles by linking charging networks from various providers. This network includes over 500,000 connected charging stations and has partnered with more than 1,250 B2B companies in 52 countries spanning four continents. In addition to serving as a roaming platform, Hubject provides technical connections and contractual support for eRoaming in the electric vehicle charging industry.

Open InterCharge Protocol - the structure

Open InterCharge Protocol (OICP) was developed in 2012. Hubject proclaims that OICP is “the most widely implemented communication standard between European eMSP and CPO systems”.

The general structure of the OICP is divided into two parts - for the eMobility Service Providers and Charge Point Operators, nevertheless, the product offer is constantly being developed.

OICP for Charge Point Operators

Charge Point Operators (CPOs) have the opportunity to benefit from the SHARE solution. This solution enables customers who have a contract with an eMobility Service Provider (EMSP) to use the CPO's charging infrastructure for vehicle charging through eRoaming. To make this possible, CPOs must establish a connection with the HBS (Hubject Brokering System) eRoaming platform. The HBS operates as an open marketplace for eMobility, fostering an interconnected network that benefits all participants in the end.

OICP for eMobility Service Providers

eMobility Service Providers can benefit from the CONNECT solution, which enables them to provide EV drivers with access to public charging infrastructure across international borders. Through the intercharge network, eMSPs' customers can easily identify available charging points using the recognizable compatibility symbol, the intercharge logo. By connecting to the intercharge network, eMSPs' customers gain the ability to utilize all charging points offered by participating Charge Point Operators through eRoaming. Similarly to CPOs, eMSPs also need to connect to the HBS in order to achieve that.

Additionally, for eMSPs, there are two distinct ways to be connected to the Hubject platform:

  • Offline EMP: has no real-time connection for authorization to the Hubject platform.
  • Online EMP: is fully connected to the Hubject platform via a real-time interface.

The protocol is readily accessible to the public without any associated fees or mandatory registration. Since May 2019, OICP has transitioned into an open-source protocol, available free of charge, and can be obtained from Hubject's website and open-source code distribution platforms. The primary goal is to involve a broader range of stakeholders in the ongoing development of OICP. This protocol is released under the Creative Commons Attribution-ShareAlike 4.0 International License, allowing for straightforward distribution and sharing under the same terms. Furthermore, Hubject provides Hubject-compatibility certification for those seeking to ensure compatibility with their systems.

Open InterCharge Protocol - versions and technical specification

OICP Releases

OICP follows a distinct release policy where each service is versioned separately and independently from the OICP version itself. For instance, there could be an e-roaming authorization service in version 2.1 while the OICP version is at 2.2 concurrently. With each new OICP release version, a corresponding service version specification is introduced, and these are the supported services. Hubject commits to providing support for each new OICP release version for a minimum of two years. Lastly, any new implementations should be carried out using the latest available OICP version to ensure compatibility and adherence to the most up-to-date standards.

The most recent version is the OICP 2.3. The newest update of the protocol follows market requirements - improves the POI quality in an upscaling market, calibration law compatibility, data process performance, and offers higher transparency on the different charging use cases. Additionally, Hubject offers helpful and relevant for CPOs set of remote testing functionalities, for complex examination of various use cases.

OICP is formed on SOAP (Simple Object Access Protocol) and uses an object-based approach. It’s a real-time protocol that also offers asynchronous operations. Although a back-up database is provided, Hubject doesn’t actively support downloads to the charging station. The platform maintains a record of the transaction data.

OICP Market roles

The OICP protocol documentation establishes market roles as follows:

  • The EV user/owner wants to charge an EV at a charge point/charge station, and has an agreement with the eMSP.
  • The eMobility Service Provider (eMSP) wants to enable EV owners the access the charge points. In most cases, the eMSP has a valid contract and transfers information with the Charge Point Operator via Hubject’s platform. Hubject offers connection via eMSP aggregator, which enables communication with the platform. This means several eMSPs can integrate via an eMSP aggregator, hence, the sub-partners do not need to associate with Hubject.
  • The Charge Point Operator (CPO) manages a charge point. The operator has a signed contract and exchanges information via Hubject’s platform. Like eMSPs, several CPOs can integrate via a CPO aggregator. Appropriately the sub-partners do not need to register with Hubject, because the communication with Hubject is done via the CPO aggregator.
  • Hubject, being a roaming hub, facilitates communication between eMSPs and CPOs via the EV roaming platform Hubject Brokering System.

Open InterCharge Protocol - functionalities & services

Services for CPOs & eMSPs

The OICP encompasses several distinct services within its framework.

First, there's the e-roaming authorization service, which handles all aspects of authorization, including remote start/stop functionality and the processing of Charging Data Records (CDRs). Next is the e-roaming reservation service, designed for reserving charging stations. This feature can be optionally offered by Charge Point Operators (CPOs).

Then, we have the e-roaming EVSE data and e-roaming EVSE status services. These services involve the exchange of Electric Vehicle Supply Equipment (EVSE) information. EVSE data focuses on static information such as location, while EVSE status deals with dynamic data.

The e-roaming dynamic pricing service, despite its dynamic nature, primarily deals with flexible pricing, which we'll delve into further later. For now, it allows the exchange of pricing product details and identification of pricing products associated with specific EVSEs.

Lastly, there's the e-roaming charging notification service, which covers all events that can occur during a charging session, including start/stop actions, progress updates, and error notifications.

From the perspective of eMobility Service Providers, the services offered are quite similar to those of Charge Point Operators (CPOs), with one notable distinction. EMPs have the e-roaming authentication data service at their disposal. This service enables EMPs to transmit authentication data to the Hubject platform. This capability allows EMPs to function similarly to an offline EMP, a concept we've discussed previously.

OICP Functionalities

  • Roaming via hub - The CPO and the eMSP system connect to based on web services Hubject B2B Service Platform. Both parties, the CPO and MSP, have an e-roaming contract through Hubject.
  • Ad hoc payment - ‘Intercharge direct’ is an ad hoc payment dedicated solution integrated in OICP and Hubject platform. This allows any contractless EV owner to charge up and pay at any charging station.
  • Authorization - Hubject links the IDs of eMSPs or CPOs and SSL certificate information. Then each does or does not authorize the charge session. Hubject’s database performs as back-up, but not actively support downloads from their database to the charging station.
  • Reservation - An EV owner can book a charge point e.g. via eMSP app. Hubject checks charge point compatibility with the EV.  If matches send the request to the CPO, which in return responds whether the booking was successful. A reservation can also be withdrawn.
  • Billing - Charge session data is recorded in Charge detail records (CDRs). Hubject passes on the CDR to the eMSP and stores the CDR in the system.
  • Charge point information - Uploaded charge point information can be distributed between CPOs and eMSPs via Hubject’s platform. The information areas are charge point ID, CPO, charge point name, charge point location (name, address, geocode, type), time zone, opening times, current availability, accessibility, tariffs, authorization modes, means of payment, charge mode, connector type, maximum power, hub connection, support contact number, reservation possible, real-time status information possible, predictive charge point usage, smart charging services, and the date of the last update. OICP maintains flexible pricing based on charge facility, charge point location, and time-of-use.
  • Real-time charge point information - This covers dynamic charge point availability status and tariff information.
  • Session information - Session ID, service specifics, charge point ID, authentication data, start and end time of charging, start and end time of connection, starting and stopping meter value, meter value in between, consumed energy, CPO ID, MSP ID.
  • Remote start/stop - From within the eMSP application, a charging session can be operated.

For those who look for a more in-depth knowledge, we have published a comprehensive training covering all the technical aspects of OICP.