See the final 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!


Subscribe to our YouTube channel to make sure you don't miss out on the upcoming training entries.

CPO eRoamingAuthorization + eRoamingReservation

CPO eRoamingEVSEdata + eRoamingEVSEstatus

CPO eRoamingDynamicPricing + eRoamingChargingNotifications

EMP eRoamingAuthorization + eRoamingReservation

EMP eRoamingEVSEdata + eRoamingDynamicPricing 

Open InterCharge Protocol Training - Lesson 9

In this module we will briefly compare the OICP protocol with another very common and popular protocol called Open Charge Point Interface. We will also present a charging terminology and topology model commonly used in Europe. We will see how OICP and OCPI protocol fit into it. Open Charge Point Interface protocol supports communication between eMobility Service Providers and Charge Point Operators. This protocol is free to use and is developed and maintained by EV Roaming Foundation. Details of OCPI protocol will not be covered in this course. We will only compare it with the OICP protocol and point out the most important features.

OCPI protocol works mostly in the peer-to-peer communication model and hub model is also offered in the latest 2.2 version. OICP, however, works only as a protocol between different partners and the hub. That influences how you implement and integrate with those two protocols. In case of OCPI, you can start implementation almost immediately and test it against any other company solution. With OICP however, you can start to build a model and write some implementation but in order to fully test integration, you need your own QA environment and access to the Hubject platform. The next difference is modules vs services approach. In OCPI, you have multiple modules. Each module covers a complete functionality over a specific aspect, like i.e. charging sessions. The division of previously mentioned aspects is more granular. Therefore it is more flexible. OICP, however, operates only on a few services which cover only the most important issues in the eMobility world. The list of required services is not so big, so in theory the implementation should be easier. In practice you will need more services than it is required in order to be effective.

The next technical difference is how the operations are modeled. In OCPI you will use multiple http methods in order to perform specific actions for EMP or CPO. In most of the modules you are not limited and you can push your data as well as pull it from others. In OICP you will use only post http method in order to model push and pull operations. What's more? Those operations are not bi-directional and valid only for the specific role. For example; EMP can push authentication data to the Hubject platform but CPO cannot pull it. OICP protocol is definitely well defined, standardized and more mature. It's clear that Hubject does not allow us to do everything, but every exposed operation is easy to understand, easy to implement and covers most of the needs. The only drawback is that introducing any kind of change to the protocol is hard and takes more time. OCPI on the other hand is more flexible, due to its structure and EV Roaming Foundation policy. They've built a community which can suggest what kind of changes are necessary and what kind of solutions may be good to introduce in the future.

One of the most important differences we have encountered is connected with previously mentioned authentication data. In OICP, CPO cannot pull EMP authentication data from the Hubject platform. While in OCPI, CPO can pull it directly from an EMP partner. But why is that so important? Let's imagine that you've built a complex CPO platform which integrates with multiple partners with OICP, OCPI and some other protocols. You may have a situation, where some end customer would like to start a charging session under a charging point with an RFID card. You as a CPO need to validate if a given user is able to do that. Therefore, you need to authorize the request in some EMP partner, but how would you know which partner is involved? If you have EMSP authentication data, you can build a simple eRoaming table and know exactly which partner is involved. Unfortunately, OICP does not allow to pull EMP authentication data. Therefore, you cannot fully build that roaming table. If you receive a request and you do not know which partner is involved, you need to treat Hubject and its authorized request as a fallback and if you have other protocols with similar behavior as in OICP, you need to perform a broadcast in order to authorize the request.

The next thing is that OCPI offers more details about ongoing charging sessions which is a crucial feature for other EMSP partners. Also, basic smart charging functionalities are offered in 2.2 OCPI version, while OICP does not cover this topic for now. The last thing is strictly business related, OCPI is more flexible, therefore it makes it easier for you to build your own business processes and business model on top of it. You can define your own rules and use functionalities offered to you in many combinations. On the other hand, OICP is designed to be compatible with processes defined by Hubject, so sometimes you need to be compliant with them in order to integrate and use full of its potential.

Now, I would like to present to you a charging topology model which is standard in Europe. At the highest level, we have a charging pool which is basically a location of a given charging spot. Each charging pool may have multiple charging stations. You can think of them as a physical stand next to the parking spot. Each charging station may have multiple charge points which represent supply equipment needed for charging, i.e. we may have two parking spots next to the one charging station with two charge points. It allows both of the electric vehicles to charge at the same time. At the lowest level we have connectors i.e. type 2. Each charging point may have multiple connectors but only one can be used at the moment.

As you can see OCPI and OICP are not fully compatible with European standard. OCPI at the highest level has a location which can be related to the charging pool. Charging station level is omitted, so the next level is EVSE. EVSE in general is the same concept as a charging point, but as far as I recall there are small differences. At the lowest level we have connectors which are almost the same as for European standard.

When it comes to OICP, Hubject introduced a similar vocabulary to the protocol by adding charging pool ID and charging station ID, but those are just IDs. Location is still a part of an EVSE and is not separated out. Also, OICP does not have a separate model for connectors. Those are present as the plugs in EVSE data model and are not separated as an entity according to the european standard. My general advice is to use vocabulary and domain model from the European standard, because there is a probability it will become a mandatory standard in the future. Of course, because of those differences it might be quite hard to bring together those three models, so everything depends on your case. If you are a CPO, then it might be good for you to have a four layered model, because you can define different logic on each layer. But if you are an EMSP it might be quite hard to present all the data in an attractive form to the end customer.

Finally, I would like to present to you some good-to-know things. First let's focus on no delete policy and using full load operation instead. The main reason for using full load operation is because Hubject is versioning every data set that was pushed to their platform. Because of that, you can see exactly how the data has changed over time and you have a possibility to roll back to some old version of the data set. The next reason is because delete operation is not the soft type. It will not create any kind of event and it's hard to keep everything consistent. It's better to use full load operation to always update the latest data set of i.e. EVSEs. Worth mentioning is that Hubject agrees on 24 hours eventual consistency. Therefore, it's possible to perform one full load operation in the night and not delete a single EVSe once it will happen.

As I’ve told you before, direct communication with Hubject may be very beneficial, but only you will understand their API better, but they can also help you in more complicated ways. For example; by providing a custom API. Let's take a look at the case with lack of authentication data for CPO. We have talked with Hubject about this problem and it turned out that this operation was exposed before, but due to some problems and misunderstandings it must have been removed from the API. Maybe they can cooperate and unlock this functionality only for your specific environment if that's what you really need.

The delta pool last call parameter cannot be combined with other filterings like i.e. search center. According to Hubject documentation, there are some corner cases where it can lead to some data inconsistency on the EMP site, but we do not know more details. Nonetheless it's definitely worth remembering.

When it comes to pagination it's good to know that the default number of records provided in paginated data response is 20 records. The maximum number of records that can be obtained in one single page is 2 000 records.

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 9

11 MAY 2022 • 10 MIN READ