Behind the Scenes of Plug & Charge: The RAAR Process Explained

1. Registration

2. Authentication

3. Authorization

4. Reconciliation

Plug & Charge starts with a one-time setup that links the driver’s charging contract to their EV using a digital identity. This identity is established using pre-installed certificates that comply with the ISO 15118 standard for secure EV-to-charger communication. ISO 15118 is the international standard that defines the safe exchange of information between EVs and charging stations. It establishes interoperability between charging networks and devices, which is essential for Plug & Charge to function.

These digital certificates are issued and validated by a Public Key Infrastructure (PKI), a trusted authority. One certificate identifies the vehicle, while another represents the driver’s mobility contract, created when they accept the terms of a mobility operator and provide a payment method.

Once this contract certificate is installed in the EV, it’s registered using an Open Charge Point Interface (OCPI) token, which is shared with the ChargeHub roaming hub.

The hub then shares the token with participating Charging Point Operators (CPOs), confirming that the vehicle is ready for P&C.

Ultimately, these certificates function like a digital passport, authenticating the EV and enabling it to seamlessly connect with any compatible charging station, without requiring an app, card, or manual step.

It’s important to note that this registration process only needs to be done once. After this initial setup, the EV is ready to use Plug & Charge effortlessly across compatible networks.

Authentication is the process of establishing mutual trust between the EV and the charging station, all without driver interaction. Unlike other methods, such as scanning an RFID card, using a mobile app, or tapping a credit card, Plug & Charge handles authentication automatically through encrypted communication between the vehicle and the charger.

As soon as the vehicle is plugged in, a protocol defined by ISO 15118 is triggered. The car initiates a digital handshake, prompting the charger to present its certificate. This exchange is secured and verified through a Public Key Infrastructure (PKI), a trusted system that ensures both the EV and the charging station can authenticate each other. If the certificate is recognized and valid, a secure, encrypted communication channel is established.

This encrypted exchange forms the foundation of a secure Plug & Charge session. It ensures that both the vehicle and the charger can verify each other’s identity before proceeding, just like verifying credentials before opening a private conversation.

Authorization determines whether a charging session is permitted under the driver's existing contract.

When the vehicle initiates a session, the CPO backend checks the EMAID (eMobility Account Identifier) against its list of approved mobility operators. If there’s a direct agreement in place, the session is immediately authorized, much like recognizing a known RFID card.

If no direct agreement exists, the CPO backend uses an OCPI token to contact a roaming hub, such as Passport Hub. The hub identifies the appropriate mobility operator, forwards the request, and returns a validation or rejection based on the user’s contract status, all within seconds.

This roaming-based flow is what enables true interoperability. Platforms like Passport Hub act as bridges between networks, allowing drivers to charge seamlessly across providers, even when there are no direct partnerships between their mobility operator and the charging station.

In short, roaming unlocks scalable, cross-network charging, a critical ingredient for frictionless EV adoption.

Reconciliation is the final stage of the Plug & Charge process, where transactions are verified, billed, and settled behind the scenes.

As soon as the vehicle is unplugged, the CPO backend sends the session data to the roaming hub using OCPI. This moment also marks the trigger for the driver’s payment. The hub then forwards the Charge Detail Record (CDR) to the driver’s mobility operator for billing and reconciles payments with the Charge Point Operator (CPO).

By aggregating session data and managing financial settlements, the roaming hub ensures that every stakeholder, from the mobility operator to the CPO, is adequately compensated.

To the driver, it all happens seamlessly. But for networks, this step is crucial. From the moment a vehicle plugs in, authentication, authorization, and reconciliation unfold automatically, turning a simple charging session into a streamlined, competitive service.

• OEM (Original Equipment Manufacturer): Installs digital certificates in the vehicle.

• CPO (Charge Point Operator): Operates and maintains the charging infrastructure.

• eMSP (eMobility Service Provider): Manages the driver’s mobility contract and payment.

• PKI (Public Key Infrastructure): Issues and validates the digital certificates.

• MO (Mobility Operator): Often interchangeable with eMSP in this context.

• Roaming Hub (e.g., Passport Hub): The backbone to manage charging authorization, billing and reconciliation between eMSPs and CPO.

Plug & Charge delivers unmatched convenience to EV drivers, but its success depends on robust and secure coordination between multiple actors. The RAAR process, powered by standards such as ISO 15118 and supported by a hub like Passport Hub, enables this by ensuring interoperability, automation, and trust throughout the charging journey.