Clearing House on roaming electric vehicle charging

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In a previous article, we brought a discussion about challenges to electromobility in Brazil and showed how roaming can become an option to address some of the issues that are imposed on the spread of electric vehicles in Brazil.

Roaming is a solution used in the telecommunications world to allow users to use their mobile phones even when they are outside the coverage area of their carriers. In electric mobility, it can also be used to allow drivers to charge their vehicles at stations of other operators.

In this article, we will take another step to understand roaming in the context of electromobility, identifying different commercial arrangements and the role of Clearing Houses, new actors that can help make roaming possible between different recharge operators.

The roles of recharge companies

First, we will introduce the different actors in an electric vehicle recharge ecosystem. Companies operating in the electromobility ecosystem can take on two distinct roles: eMSP (Electric Mobility Service Provider) and CPO (Charge Point Operator).

eMSP (Electric Mobility Service Provider)

Electric mobility service providers (eMSPs) are the companies responsible for making recharging services available to end-users, who may be individuals or even companies that own electric vehicles. They offer mechanisms to locate charging stations, authenticate and charge their users, among other services.

The recharge services offered comply with the conditions and tariffs defined in the contracts between the users and the eMSPs. It is worth noting, however, that MSPs do not necessarily have their own infrastructure of charging stations. For this, they can count on CPOs.

CPO (load point Operator)

Charging point operators (CPOs) are companies that typically have their own charging stations, although they may also operate third-party stations. They are responsible for the installation, operation and maintenance (O&M) of the charging stations on their network. CPOs make their charging infrastructure available to end-users (individuals or companies) through one or more eMSPs.

Thus, in a recharge Network, end-users (individuals or companies) contract the service of an EMS to access the recharge stations of a CPO — which may or may not belong to the same EMS company. If they are different companies, the eMSP and the CPO must also have a contract between them.

The figure below illustrates a possible scenario with different recharge networks. The user has a contract only with the service provider eMSP1. EMSP1, in turn, has an agreement only with the operator CPO1. In this way, the user can recharge his vehicle only at CPO1 stations.

When the user is in a location where the CPO1 operator does not have charging stations, he will not be able to recharge his vehicle, even if there are charging stations in the region, as indicated by the CPO2 and CPO3 operators in the figure.



An alternative for the user would be to establish contracts with the eMSP2 and eMSP3 service providers (figure below). However, this process can be impractical for users, especially if there are many companies operating in the regions in which it circulates.


Roaming arrangements between eMSPs and CPOs

Roaming can be a solution so that users of an EMS can use the charging stations of other operators (CPOs) without the need to hire other service providers (EMS).

In a roaming solution, a recharge service provider (eMSP) can enter into contracts with multiple recharge operators (CPOs), enabling its users to use the recharge stations of all connected CPOs, as shown in the figure below.


In this arrangement — known as point-to-point (or “Peer — to-Peer”, P2P) – the communication between the companies ‘ systems (eMSP and CPOs) must be carried out through standardized communication protocols, which allow the interconnection of the different systems. There are already some initiatives for the standardization of roaming that allow the P2P arrangement between eMSPs and CPOs, such as OCPI (Open Charge Point Interface) and OHCP (Open Clearing House Protocol), which use the OCPI P2P and OHCP Direct protocols respectively, as indicated in the figure above.

The P2P roaming mechanism allows users to perform recharging at stations of different carriers. However, it requires companies (eMSPs and CPOs) to establish contracts between them to define the terms of the service. Each PMSC must establish direct contracts with each CPO it wishes to include in its recharge services (as indicated by the figure below), which can become a problem, especially if there are a large number of companies in the recharge ecosystem.


Another arrangement that has been used in some recharge ecosystems is the definition of a centralizing element that concentrates the interaction between the various MSPs and CPOs, as indicated by the figure below. This centralizing entity, called a clearing House or Hub, allows multiple CPOs charging stations to be accessed by multiple eMSPs users. In this case, each company (eMSP or CPO) needs to establish a single roaming contract with Clearing House.


The technical feasibility of this approach also depends on the definition of communication protocols that standardize the interconnection between the systems of the different companies that are part of the solution. Among the protocols that have been defined that allow roaming in hub are OCPI Hub and OHCP (already mentioned earlier for also allowing P2P roaming) and the OICP (Open Interchange Protocol) and eMIP (eMobility Inter-operation Protocol) protocols, as indicated in the previous figure.

In this scenario, Clearing House represents a new role of the recharge ecosystem. It can operate in this market without its own charging infrastructure and also without its own end-user base. Thus, Clearing House is responsible only for the interconnection of multiple eMSPs and CPOs and receives a fee for the recharge transactions carried out between them.

Clearing House features

Clearing House offers some services for eMSPs and CPOs to enable the roaming process. Among its main tasks, we can name:

Station information sharing

Clearing House should receive static and dynamic information from CPOs charging stations.

The static information of a given station can include, for example, the address of the station, the type of equipment (indicating the type of plug, the power, voltage, recharge speed, etc.).authentication mechanisms of users (via RFID card or Smartphone App, for example), the opening hours of the station, etc.

Dynamic information, in turn, represents the state of the seasons over time. They indicate, for example, whether a given station is in operation, whether it is available or in use at a given time, etc.

The static and dynamic information received by Clearing House is shared with the various MSPs. EMSPs can use this data to provide Station search engines for their end-users.

Authentication of users and authorization of recharges

In order for only registered users to have access to the stations, Clearing House must also authorize eMSPs users before enabling a recharge at CPOs stations. Different authorization mechanisms can be used, from RFID cards to smartphone Apps.

However, it is important that this authentication and authorization process is carried out without compromising the identity of the eMSPs users. That is, without personal data being exposed to the CPOs. This process is typically done using tokens, which are unique identities that can represent users and can be safely used by both eMSPs and CPOs.

Registration of transactions and pricing

Once authorized, a user will be able to initiate a recharge at a network station. Records with recharge details (or Charge Detail Records, CDRs) will be collected by the CPO operating the station and forwarded to Clearing House. The CDRs shall include information related to the recharge time interval as well as the electricity consumed.

Clearing House shall forward the CDRs to the eMSP of the user who is performing the recharge, so that eMSP can charge the user for the recharge according to its contract conditions. Clearing House shall also ensure that eMSP remunerates the CPO according to the energy made available for recharging.


This article showed how electric vehicle recharge roaming can be achieved through two different arrangements or paradigms, P2P roaming and Clearing House roaming.

P2P roaming allows the interconnection of multiple eMSPs and CPOs. However, it requires the definition of bilateral contracts between these companies, which may hinder their expansion with the increase in the number of companies in the ecosystem.

Roaming via Clearing House solves the problem through a new actor that centralizes the contracts of companies that are part of the e-mobility ecosystem. Some roaming solutions that use Clearing Houses as centralizing entities have been used in some countries.

A Hubject is an example of a company that acts as Clearing House in Europe, enabling roaming for users from different countries. It is also one of the leading companies in the OCPI protocol standardization consortium. According to the company’s website, its network already has more than 750 partner companies, operating more than 250 thousand charging stations.

Despite the success, the roaming solution with Clearing Houses is also the target of criticism, since the approach implies the inclusion of a new actor in the ecosystem, which should be remunerated for its services through fees that can make the recharge more expensive for end- users

Possible evolution of the solution could be proposed, using Blockchain to eliminate the need for a centralizing entity, bring trust between actors and ensure security and transparency for recharge transactions, but that’s the topic for a next article!

Venturus develops innovative projects, applying cutting-edge technologies to add value to its customers and partners. To know more about this or other topics that we act contact us or visit our website.

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