See the sixth lesson of our comprehensive eMobility training on OICP!

Having a chance to work with well-established startups from the e-mobility sector, Bartek gained invaluable knowledge on the industry requirements. On his path, he was given the opportunity to work on numerous EMSP applications and CPO platforms. Bartek is also our Head of Delivery.

Bartłomiej Łazarczyk

 is happy to introduce you to the Open Standards course led by our e-mobility expert - Bartlomiej. Throughout the following lessons, we will uncover the technicalities and functionalities of the OICP - a protocol developed by 

 - as well as business aspects for e-Mobility Service Providers and Charge Point Operators.

Such a knowledge-pack should serve everyone operating in the e-mobility industry as it unfolds the most crucial aspects of navigating through Open Standards utilization and many more!


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CPO eRoamingAuthorization + eRoamingReservation

CPO eRoamingEVSEdata + eRoamingEVSEstatus

Open InterCharge Protocol Training - Lesson 6

Tariffs and pricing issues are very complicated and hard to model. Tariffs may differ depending which aspect is concerned. Going from top to the bottom: we may have an end user which has an individual contract with EMP. EMP can offer him favorable rates under specific conditions, but of course it depends on the charging infrastructure and fees that EMP would like to charge. In order to offer charging infrastructure to end customers, EMP must have a contract with CPO, which can specify different rates than those offered to the end users. Of course, CPO may specify different rates per EVSE, their location, per day time and of course different rates per connector type. This is just a big picture overview and a small presentation of dependencies. In practice, each partner may have its own individual business model and settlement model

Comparing the Hubject model to the model that was presented before, Hubject aims to create a common tariff interface for CPO and EMP by having a specific pricing product within a service offer that EMP can subscribe to. OICP was not designed to cover end user tariffs. Their pricing product interface should be so flexible to cover different pricing depending on charging infrastructure i.e. different rates for type 2 connectors. This solution comes with a trade-offs. If you would like to integrate with the Hubject platform, it would be harder for you to create your own business model, especially as a CPO.

Besides standard pricing and product pricing which were briefly explained before, Hubject created the flexible pricing which allows CPO to offer differentiated pricings in many dimensions. It can depend on charging facility, location, daytime and combination of all above. All of those conditions are in the form of pricing product, which can be assigned to EVSE’s. Flexible pricing offers an API which is clear and understandable between both of the parties. On top of that, Hubject also created dynamic pricing, which enables for almost real-time updates between CPO and EMP. Unfortunately, because of its nature, dynamic pricing cannot be offered to everyone. It must be a bilateral offer. CPO and EMP must agree on business and legal specifics and their system must be prepared on such frequent tariff updates for just one party.

eRoamingPushPricingProductData is an API operation that allows CPO to upload pricing product information. In order to do that, CPO must create flexible or dynamic pricing in authorization service offer. It can be offered to all or per specific EMP. Of course, Hubject will check if there is a valid flexible or dynamic pricing before accepting the request. Hubject will also keep history of all change data records similar as in other services.

eRoamingPushPricingProductData request contains a lot of information about pricing. “PricingDefaultPrice” is quite obvious. It's the default price for a charging session. “AdditionalReferences” can be used for specifying additional pricing components, like start fee, parking fee, fixed fee or minimum/maximum fee. “IsValid24Hours” is self-explanatory, but you need to remember that it is assigned to pricing product not EVSE. “MaximumProductChargingPower” is expressed in kilowatt hours. “PricePerReferenceYouNeed” is a price per reference unit, in our example per hour in product price currency in our example in euros. “ProductAvailabilityTimes” specifies when exactly a given pricing product can be applied, for example it can tell specific begin and end hour of weekday.

Second operation to perform in eRoaming Dynamic Pricing Service is eRoamingPushEVSEPricing. It is used for assigning specific pricing products to EVSE IDs. Hubject will verify if service offer was created before and if pricing product can be assigned to EVSE. Hubject will also keep a history of all changed data records.

Request for eRoamingPushEVSEPricing is pretty straightforward, you need to provide a list of EVSE IDs and then provide a list of products that should be assigned to giving EVSE.

eRoamingChargingNotification is optional, but it's very important from an EMP perspective. It covers charging session functionality similar to a session module in OCPI protocol. In general, Hubject treats any kind of event that can happen during charging as a notification. Each notification may reflect various actions i.e. charging session started, update meter value, charging session ended and different kinds of errors that can happen during charging. Hubject will forward every notification received from CPO directly to the interested EMP. That allows EMP to present more details regarding the charging session to his customers, therefore it's very important for him to receive such kind of information.

Successful authorization and plugged cable does not necessarily mean that the charging process has started and energy is flowing. OCPP protocol which covers communication between chargepoint and chargepoint operator finds a lot of scenarios for charging session start, which must be handled by CPO. If everything goes right, CPO will receive a specific message that says a charging session has started. In this case CPOmay inform EMP about that by sending eRoaming charging notification start

When a charging session has started, EMP and its customer would like to receive more details about the ongoing charging session. They would like to know what is the energy consumption, duration, charging characteristic for some visualization and maybe even some predictions. The typical scenario is that CPO will receive meter values from chargepoint every 15 minutes via OCPP protocol. Therefore CPO may notify EMP about it and send some useful charging session details with eRoaming charging notification progress. Because those notifications are not crucial and not so frequent Hubject recommends at least a five minute frequency between two progress notifications.

CPO may also notify EMP, that the charging process has stopped. It can mean that energy is not flowing and the customer may be informed that his electric vehicle has been fully charged. a notification itself that does not mean that the charging session has been finished. In order to end the charging session and unlock connector you may use authorized stop request normal or remote or CPO may finish charging session on its own and push CDR right after it happens.

Of course, during the charging session there can be a lot of unexpected events i.e. stop triggered by charge points, charging fluctuations or even charge point damage. From an EMP perspective, it's very important to know what is going on and to inform its customer that his charging session cannot be finished successfully or that it was finished before his electric vehicle has been fully charged. In this case, CPO can send an eRoaming charging notification error with some details regarding the problem.

Data model of eRoaming charging notification may differ a little bit depending on the type of notification, but for most of the parts it looks almost the same. Charging duration and consumed energy progress is calculated for the time between charging start and event occurred. Charging duration is expressed in milliseconds, consumed energy progress is expressed in kilowatt hours. Meter value in between is an object representing a list of our meter values, which can be used for specifying charging characteristics. Of course, this data will not be present in eRoaming charging notification start. For error notifications we may also see error type and error additional info, which can be used for specifying more details about charging problem that has occurred.

When it comes to the rest of the fields, we have already seen them before in other data models. So there is no need for an explanation.

To sum up we have covered all OICP services from a CPO perspective and seen how the flow, business logic and data model looks like. Although some services are mandatory in order to integrate with the Hubject platform. Here you have a list of operations network marked as a mandatory in OICP documentation for CPO those operations are
eRoamingAuthorizedStart, eRoamingAuthorizedRemoteStart, eRoamingAuthorizedRemoteStop, eRoamingChargeDetailRecord, eRoamingPushEVSEData, eRoamingPushEVSEStatus. Unfortunately OICP documentation is not perfect and definitely is not clear in many places. In case you encounter some problem, my general advice is to contact the Hubject support team directly. In the past we had a situation where we thought some implementation of operation was mandatory, but it turned out that in our case maybe it's not needed at the moment. After contacting Hubject they said we can postpone it for now and we have definitely saved some time.

eRoaming Hubs explained

Get our comprehensive PDF packed with knowledge on eRoaming, hubs and protocols!

Being an eMobility leader in various projects across multiple startups, Piotr was responsible for OCPI and OCPP integration as well as EMP and CPO platforms development. With extensive expertise in the open standards field and eMobility tech solutions, he is leading teams of experienced developers and contributing with invaluable knowledge and experience.

Piotr Majcher

Certainly, roaming is something known to everyone at this point. However, what that has to do with eMobility?

Being a broad term for services allowing for connection outside of the usual network, roaming turns out to be an on-point solution for EV charging. With many players in the eMobility game (i.e. Charging Point Operators, eMobility Service Providers), some type of a connector is a must. Here’s exactly where eRoaming comes into play allowing for multi-dimensional connection between operators and EV drivers.

In short, eRoaming can be established via the use of hubs and protocols. A hub here can be an open platform which, after subscribing, can be used by many operators, who operate on common terms. This all happens in such a way that a certain charging pool introduced to a common hub can then be easily used by clients (EV drivers) of different providers. Such a solution allows electric vehicle users to charge their car across cities/countries with limited hussle.

In order to facilitate such a solution, the hubs developed their own open protocols, which are essentially responsible for the connection. They also define the functionalities of each eRoaming platform.

Amongst the existing hubs, we can differentiate three major ones. They all come with their own open standards and unify hundreds of CPOs and EMPs as well as millions of EV drivers.

The three biggest hubs and their protocols are:

(eMobility Inter-Operation Protocol - eMIP)

Apart from the proprietary protocols coming from hubs, it’s worth mentioning that there's also an independent one - 

Open Charge Point Interface Protocol (OCPI)

. It allows for eRoaming between the hubs as well as peer-to-peer connection.

To learn more about eRoaming, hubs & protocols, their importance and functionality as well as the future of eMobility - take a look at our exclusive paper covering all that needs to be covered on the topic!

Download our comprehensive PDF and learn about the pricing structures in e-mobility

Although it would seem rather straightforward, the pricing system within the EV charging environment extends further than just to the payments made by electric vehicles right after they charge their car.

Being such an interconnected network of mutual dependencies between numerous involved parties, e-mobility charging services require various levels of settlements.


It must be noted that it takes a few units to build up and manage a charging network. From 

, which manufacture the hardware side of required components (connectors, chargers, cables, etc), through 

, which are responsible for the backend management, all the way to 

, which determine the final user (here: EV driver) experience, there is a whole network of reliabilities.

Put simply and briefly, CPO’s are to establish billing connections with both EVSE and eMSP’s, in order to put the entire charging formation in place, while ensuring all parties receive transparent information and clear instructions.

To facilitate it, there are multiple types of pricings and contracts, some of which allow for complex, dynamic price models. Such undertaking is required so that eMSP’s can shape their end-users pricing often based on certain conditions, leaving the rates flexible.


Interoperability - the core of proper functioning

It should go without saying, that managing a pool of charging stations - oftentimes distributed across entire countries/regions - is not an easy task to handle and can only be achieved via advanced levels of interoperability and clear, unified procedures.

Open Standards are the chief example of how this can be achieved and maintained. Through the utilization of API’s like OICP the flow of information can be sustained in a transparent manner. This allows for a seamless communication and can facilitate the management of a vast majority of proceedings remotely, which comes in handy while developing a state-wide network, especially when there are numerous parties involved.


Knowing the behind-the-scenes nuances and arrangements, we prepared a comprehensive paper portraying the pricing structure within the e-mobility industry. Those who are willing to learn more about tariffs within charging services, should definitely find it useful.

Download our free paper and broaden your horizons with some great knowledge!

E-mobility tariffs. How is the pricing structured within the industry?

Open standards can be a game changer for both eMSP's and CPO's. Here is why.

The initial stages of technologies lead to various types of solutions addressing the same problem. Each company develops a different approach. At the beginning of the XXth century, when commercial electricity had come to the mainstream, multiple energy producers offered power supply with miscellaneous frequencies and voltages. As time passed, governments began to impose certain standards on suppliers. This standard-setting led to the joint effort to create the first power grid.

From the first power plant to the moment when all energy providers linked to the same network, decades passed. This was only possible because they took a mutual direction.

 - literally and figuratively. With global warming, exhaustion of solid fuel resources, and lifestyle changes, companies face the challenge of how to provide accessible new charging forms of green power.

Now, as the e-mobility era is here, we are on the same page, like we were at the very beginning of the XXth century. We already have plenty of providers: eMobility Service Providers (eMSP) and Charge Point Operators (CPO) - two substantial sides of the e-Mobility world. One of the main challenges ahead of this market is to deliver the best user experience, at possible minimum resources use. As usual, user experience is a matter of well-designed apps, customer support, and simplicity itself. But there is an additional fact. End-users need to be able to charge cars at any charging station without being concerned about accessibility. The issue is - having the contract signed with the Charge Point Operators recharging point service. How to achieve this? Partners must take the same course, and this is where the standards start to play a major role. There are two possibilities: Open Charge Point Interfaces or Open Intercharge Protocols. What are the benefits?

The main goal of the Open Charge Point Interface (OCPI) is to allow electric vehicle drivers to charge their cars at any station. OCPI defines a set of modules that cover most cases the driver may need. There are two technical modules that are used to establish connectivity between two platforms using OCPI: Credentials module and Versions module. Other modules are strongly related to real-life use cases. These would be:

Locations - module responsible for sharing information about the Charge Points, like address, geolocation, real-time data about the current status, electrical parameters.

Sessions & Commands - module allows the end-user to start the charging session and be informed about the current status of the charging session.

OCPI is an open standard, and what may be very important for the adopters - it’s very flexible. For instance, CPOs (Charge Point Operators) may implement only the Locations module (apart from two technical mandatory modules) when only sharing Point Of Interest data. With no necessary exposing the eRoaming functionality. But the ultimate goal for many CPOs is to allow end-users to charge their car. In that case, many more modules need to be implemented (Sessions, Commands, CDRs). Some others are optional, even for the eRoaming (Tokens, Tariffs), and that depends on the agreement between certain allies. It’s in terms of how financial flow and security is modeled.

The biggest advantage of having OCPI implemented is that it’s almost a one-time investment. The initial effort is significant, as it might be challenging to transfer internal models and processes to the OCPI. But once it’s done for a partner, it opens the company for quick and cost-effective integration with a lot of other associates.

A bit different concept is proposed by the Berlin-based innovative company - Hubject. Hubject developed its own API (OICP) covering almost the same cases as OCPI. There is one extra. Hubject also acts as a hub. It connects CPOs and eMSPs. Once a company is connected to the Hubject platform, it becomes open for integration with any other comrade being already assigned. That’s a huge advantage because the integration is done once, with one platform, and of course it becomes profitable when it comes to an alliance with multiple partners.

Yet another advantage of the Open Intercharge Protocol is that it’s quite easy to implement. Like with most protocols, the main challenge is to synchronize our internal models with the standard one. What is comforting with OICP - there is not too much to implement. It depends on the level of integration we want to achieve, but it’s enough to implement about 5 HTTP calls to expose eRoaming through the Hubject platform.

Having in mind multiple historical examples, it may be difficult to be a part of a developed market without following widely adopted standards. Initially, it may need some additional effort. But when the standard is implemented, our platform becomes open for the whole market 

. Without it, we would need to spend weeks or months doing the integration with each partner separately.

Open InterCharge Protocole Training. Lesson 6

31 MARCH 2022 • 10 MIN READ