OCPI (Open Charge Point Interface) EV Roaming

EV Roaming Overview

EV roaming with OCPI allows a driver to charge at multiple networks using a single RFID or application. Roaming is critical to the wide-scale success of EV adoption. It is similar to the evolution of mobile telephony, where, historically, each user could only make calls on their home network. Over time, users could roam to other networks, and today, national and European regulations mandate roaming at flat prices.

The Importance of OCPI for EV Charging Infrastructure

OCPI plays a crucial role in developing and expanding EV charging infrastructure. It provides a standardized communication protocol that enables interoperability between charging networks. This interoperability is essential for widespread EV adoption. EV drivers can access a wider range of charging stations, regardless of their service provider. As a result, it reduces range anxiety and improves the overall charging experience. OCPI benefits charge point operators and eMobility service providers in several ways. It facilitates easier integration of new charging stations into existing networks. It also streamlines payment processes and enables more efficient infrastructure management. OCPI’s open nature fosters competition and innovation in the EV charging market. Ultimately, this leads to better services and more choices for consumers.

Prominent Protocols for EV Roaming

The most prominent protocol for EV roaming is the Open Charge Point Interface (OCPI), which is maintained and endorsed by the EVRoaming Foundation. Specifically, OCPI supports connections between eMobility Service Providers (eMSPs) with EV drivers as customers and Charge Point Operators (CPOs) who manage charge stations. Moreover, this protocol is free to use and independent. Additionally, it can work both bilaterally and in combination with roaming hubs. Notably, different versions of OCPI are available, such as OCPI 2.2.1, which includes enhanced functionalities, and OCPI 2.1.1, a widely adopted earlier version.

Key Roles in EV Roaming

• Charge Point Operator (CPO) – Manages a network of chargers, including maintenance and supply of electricity. Today’s chargers can be activated using an RFID, a mobile app, or contactless credit/debit cards. 
• eMobility Service provider (eMSP) – Manages a network of drivers, including providing RFIDs and a mobile app to locate chargers and holding the billing details for those drivers. Examples of eMSPs include Plugshare, Zap Map and Octopus Electric Universe in the UK, and Cellocharge in Israel.

The OCPI protocol defines the communications between CPOs and eMSPs to support token (RFID) exchange, charge point location and status, billing records, and charge point commands.  

OCPI Functional Modules

OCPI provides a common language between eMSP and CPOs to support the rapid expansion of the roaming network. Specifically, the OCPI protocol covers seven functional modules:

Mandatory administrative modules:

• OCPI Versions – This module allows the two parties to agree on the protocol version supported by both, including updates such as OCPI 2.2.1 or earlier versions like OCPI 2.1.1.

• OCPI Credentials – Involves key exchange and authorization verification for securing the communications.

Modules used for basic RFID operations and payment processing:

• OCPI Tokens – These define the exchange of tokens (e.g., RFID details) between eMSP and CPO. Additionally, the eMSP periodically sends a list of approved tokens to the CPO, which stores this list and uses it to approve charging sessions. An alternate method allows the CPO to authenticate a token in real-time.

• OCPI CDRs (Charge Detail Records) – This module defines the exchange of completed charge sessions for billing. Specifically, when a charge session is completed, a record is created containing the details of the transaction (cost, duration, energy, etc.) and sent to the eMSP for payment.

Modules used by the eMSP for creating an interactive charge point map:

• OCPI Locations – Define the exchange of charging locations data, including charge point capabilities, availability, and cost. The CPO periodically sends this list to the eMSP, which uses it to provide a live charge map.
• OCPI Tariffs – Used in conjunction with OCPI Locations to provide details of the tariff that applies to a specific charge point.  

Modules used by the eMSP for app charging initiation and app status updates:

• OCPI Sessions – Defile the exchange of interactive session data, including charging speed, energy used so far, and socket status (charging, complete, etc.) The eMSP can use this data to update the mobile app with the charging status.  
• OCPI Commands  – Allows the eMSP to send charging commands to a specific charger. Commands include Reserving a charger, starting or stopping a session, and unlocking a stuck connector. The eMSP can use these commands to implement in-app charging initiation.

Bilateral OCPI vs. roaming hubs

By default, OCPI supports the bilateral connectivity of one CPO to one eMSP. For multiple CPOs and eMSPs, a fully connected mesh would need to be created, connecting every pair. Although this approach would work for a small set of entities, it would become impractical for larger networks. Consequently, this is when roaming hubs such as Hubject, GIREVE, or e-clearing.net make sense.

The roaming hubs provide easier integration and simplify commercial negotiations. However, they come at an extra cost, which the roaming hub adds on top of the CPO pricing.

Future Developments in OCPI

The OCPI protocol continues to evolve to meet the changing needs of the EV charging ecosystem. Future developments in OCPI are likely to focus on several key areas:

1. Enhanced security features: As the EV charging network expands, robust security measures become crucial. Therefore, future OCPI versions may incorporate advanced encryption and authentication methods. These will protect user data and prevent unauthorized access to charging infrastructure.
2. Smart charging capabilities: To support grid stability and optimize energy use, OCPI may introduce new smart charging functionalities. Consequently, this will allow for better coordination between charging stations, energy providers, and grid operators.
3. Integration with other protocols: Future OCPI versions may offer improved integration with other EV charging protocols. For example, integration with OCPP (Open Charge Point Protocol) could create a more cohesive and efficient charging ecosystem.
4. Support for advanced payment methods: As payment technologies evolve, OCPI may adapt accordingly. Thus, it might incorporate support for new payment methods, such as cryptocurrency or advanced mobile payment systems.
5. Improved data analytics: Future versions may include enhanced data reporting and analytics capabilities. As a result, this will allow for better insights into charging patterns, user behavior, and infrastructure performance.
6. Adaptation to new charging technologies: As innovative charging technologies emerge, OCPI will likely evolve to support them. For instance, it may adapt to accommodate wireless charging or ultra-fast charging systems.

In conclusion, these future developments will strengthen OCPI’s role in the EV charging ecosystem. Consequently, they will facilitate seamless charging experiences and support the growth of sustainable transportation infrastructure.