Learn about the plug and charge technology and see how it simplifies the charging experience.

Grzegorz is the Head of Development in Solidstudio and he has spent quite a few years here. He’s a skilled software developer that had a chance to work on numerous eMobility-related projects for clients from many different countries.

Grzegorz Bar

In the last few years, there have been plenty of ameliorations introduced to ease the EV charging experience. Whether it’s hardware or software, major changes for the better can be observed even in places where eMobility does not have its wings spread with a full potential. Yet, even the major progress in EV charging technology, doesn’t stop frequent comparisons to what it looks like with maintaining an ICE car, which tends to be described as less complicated and simply easier.

Luckily, this view is being gradually changed by technologies implemented into the world of EV charging. In this article, we’ll take a closer look at one of the most promising charging-simplifying facilities.

allows for an EV charging event without the necessity of additional means, such as RFID cards or apps.

 With Plug and Charge, the data exchange between a charger and an electric vehicle occurs entirely automatically. This includes the authentication and authorization processes. It makes the charging process much more convenient for drivers. They don’t have to worry about connecting their vehicle to the charger or starting the charging process manually. In addition, Plug and Charge also offers improved security, as the data exchange between charger and vehicle is encrypted. It makes an EV charging experience more similar to fueling an ICE car, which does not require a sequence of minor actions to authorize a charging session.

The technology behind Plug and Charge is based on the 

. This standard defines the communication protocols and data formats that are necessary for an automated, interoperable charging process (more about it in the next section).

In order to use Plug and Charge, an electric vehicle must be equipped with a so-called Charging Control Unit (CCU). The CCU is the interface between the vehicle and the charging station. It manages the data exchange with the charger and controls the charging process. What must be remembered is that plug and charge facilitates the communication between all parties involved in the charging process, that is:

In simple words, with Plug and Charge compatible devices, the EV contains provisioning certificate and contract certificate (between the driver and EMP) and charging station contains EVSE certificate.User is identified by the ID called E-Mobility Account Identifier (eMAID) stored in the contract certificate. eMAID is also known to the eMSP for billing purposes. Thanks to that, eMSP knows which user has to be charged for the transaction started automatically just by plugging the cable. The moment an EV cable is plugged into the socket, the charging station identifies the car's certificates and vice versa.

When plugging in at a Plug and Charge enabled charger, the CCU will automatically initiate the data exchange with the charger. This includes exchanging information about the maximum current that can be drawn, the maximum voltage that can be applied, and the plug type.

Based on this information, the charger will adapt its settings accordingly. Once the connection is established, the charger will start supplying electrical energy to the vehicle. The entire process happens automatically and doesn’t require any interaction from the driver.

ISO 15118 is a joint venture of the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC) and one of a group of standards for electric vehicles. It describes the communication between a vehicle and a charging point. It has few use cases and Plug and charge is one of them.



Whole ISO 15118 is built upon Public Key Infrastructure. In Plug and Charge - The EV has the contract certificate stored (X.509 certificate). The certificate associates the end-user with the public key. Because the certificate is issued by a trusted Certificate Authority, the charging station is able to check it, and if it’s valid, the charging station believes that the user presented in the certificate is not fake. The standard ensures high security of the data exchange amongst all involved parties. The security is provided via authenticity (the verification of certificates) and confidentiality (data exchange happening via encrypted channels).

As it rapidly gains popularity amongst eMobility-related operators, ISO 15118 can be deemed one of the crucial means in ensuring the seamless operation in the world of EV charging.

In terms of its other use cases, we dive deeper into the smart charging and V2G functionalities and importance in our recent downloadable guide 

OPCP is an open standard launched by Hubject. The launch of OPCP simplifies the process of adopting the Plug and Charge technology for developers and eMobility stakeholders looking to deliver the best solutions for EV users. Standardization of said technology is a great step towards increased interoperability and unification across the industry.

Being an open protocol, OPCP gives everyone interested the opportunity to utilize Plug and Charge technology. As stated by Hubject:

“This measure is particularly relevant because the rapidly growing market for Plug&Charge results in a range of very different processes from different manufacturers. After all, unhindered access without lock-in effects will be an essential criterion for Charging Station Operators and Mobility Service Providers, offering charging solutions. In addition, qualities such as the simple and secure authentication methods for different applications and the option for further joint development in cross-sector mode are convincing. Furthermore, the opportunity for multi-contract handling is given. Multiroot handling is also implemented and compliant with ISO15118-20.”

The protocol is constantly being developed and Hubject invites any feedback and improvement ideas.

OPCP is in productive use since 2019 and is gaining more and more users amongst Charge Point Operators, eMobility Service Providers and OEMs.

It’s to no surprise, as the launch of OPCP opens the door for many to enjoy the benefits of the technology., making the charging experience a lot more effortless for the end-customers - EV drivers.


The protocol covers the following use-cases:

 (Root Certificate Pool: used for communication between the Root Certificate Pool and the various Certificate Authorities of ISO 15118 participants (V2G, OEM, MO, CPS)

 (The Provisioning Certificate Pool: providing interfaces to exchange Provisioning Certificates between OEMs and MOs)

(Certificate Provisioning Service: providing interfaces for generating and signing contract data of MOs)

CCP Service (Contract Certificate Pool: stores the signed contract data from the MOs, and provides it for the CPOs and OEMs backend)

Multiple Contracts (EMAIDs) for one Vehicle (PCID)

Interoperability between Ecosystems, V2G Root Operators etc

Multi Root -> CertificateSigningCertificate ability

ISO15118-20 prepared (separate Namespace already in account)

Smart charging

Check our friendly reminder about OCPI and its newest version.

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

Staying up-to-date with the latest upgrades across different branches of eMobility can be quite a task at times. Significant ameliorations are coming in whether it’s the hardware or software. This is especially challenging for charge point operators and eMobility service providers as they get to deal with both sides at all times. The software maintenance should aim to keep up not only with in-house changes but also (equally importantly) with external protocols that are integrated. All this in order to examine if there are new opportunities upfront our business that can be supported by the newest version of the protocol we use. Upgrades are vital also due to the fact that some of the protocols simply won’t work on outdated versions, after a major update is introduced.

Here, we’d like to briefly walk through the changes and current version of OCPI.


It’s an independent standard allowing for eRoaming between the hubs as well as peer-to-peer connection. However, OCPI also supports communication in-between roaming hubs. This way, charge point operators (and mobility providers) could exchange data, even when they are connected to different roaming hubs and when they do not have a direct peer-to-peer connection. OCPI is developed and managed by EV Roaming Foundation, which naturally is responsible for updates introduction.

In terms of functionalities brought by OCPI regarding information exchange between interested parties, there are:

 - OCPI facilitates data exchange between eMSPs and CPOs via hubs, for this operation, the protocol offers a separate hub supporting module.

 - Both eMobility Service Providers and Charge Point Operators can correlate immediately via OCPI. Separate interfaces are designed for eMSPs and CPOs.

 - The token module in the OCPI architecture supplies Charge Point Operators with the knowledge of any token information of eMSP. There are two ways to execute authorization, which could be real-time or via a whitelist.

 - On the eMSP side, the OCPI offers to make and cancel a reservation.

 - OCPI supports the basis for invoicing - sending CDRs - Charge Detail Records.

 - The protocol supports the exchange of the key details related to energy tariffs. Complex tariff calculations depend on the time charged and energy. All this information is included in the tariff module.

 - This covers: IDs, CPOs, charge point site, host, charge point name, charge point location details (name, address, geocode, type, image, platform level, directions), nearby facilities, link to a website, time zone, opening times, current availability status, scheduled availability status, accessibility, tariffs, authorization modes, payment methods, terms and conditions, charge mode, connector type, maximum power, voltage, amperage, energy mix, remote start/stop, reservation, smart charging support, and the last update mark.

 - Stats: available, blocked, charging, inoperative, out of order, planned, removed, and reserved.

real-time & static) - Covers: sessions ID, start time, end time, energy consumed, CDR ID, authorization method, location, charge point ID, meter ID, currency, charging periods, total cost, sessions status, and last update. The same information can also be in real-time.

 - CDR IDs, time, duration, finish status, and more.

 (Eichrecht) support - OCPI maintains the exchange of signed meter data which can be used to conform to Eichrecht - German calibration law.

 - The start and stop of any charging session can be done remotely via the eMSP app.

 - Several charging profiles are supported by OCPI: the cheapest charging, the fastest charging, the most environmentally-friendly charging, or no particular choices. The preferences can be registered per session by the user. The CPO can accept or decline the option. Although the smart charging profile module does provide certain options, these cannot be ensured, since other factors influence the charging session.

More information about OCPI can be found 

As described by EV Roaming Foundation, OCPI:


Offers market participants in EV an attractive and scalable solution for (international) roaming between networks, avoiding the costs and innovation-limiting complexities involved with today’s non-automated solutions or with central roaming hubs. As such it helps to enable EV drivers to charge everywhere in a fully-informed way, helps the market to develop quickly and helps market players to execute their business models in the best way.

Release of OCPI 2.2 brought big updates compared to its 2.1.1 version. New features involve:

message routing headers (ensuring better communication via hubs) and hub client information (allowing connected parties to view each other’s connection status; i.e. CPOs can check which eMPS are currently online)

Support Platforms with multiple/different roles, additional roles 

(including: type of role, business details, party ID, country code)

(via ChargingProfiles module parties, i.e. eMPS can send charging profiles to EVSE)

(allowing EMP to send preference on behalf of EV driver)

In terms of the improvements, in OCPI 2.2 we can find ones regarding

Not very much different from its previous version, OICP 2.2.1 was released as an answer to some issues reported for 2.2 version. In all cases, these are minor inconveniences, which update shouldn't be a complicated task. At the same time, version 2.2.1 can fix some irritating small details.

The changes are detailed in a table below:

OCPI 2.2.1 updates as stated in documentation by EVRoaming Foundation

The full protocol documentation with elaborated explanation and features walk-through can be found on EVRoaming Foundation website 

OCPI 2.2.1 - what's new?

Get our informative PDF on smart charging and see how it works!

Krzysztof is our Head of Products and he leads the technical development behind the suite of our ready-made solutions. Throughout the years in Solidstudio, he gained an invaluable insight into the eMobilty industry’s requirements and is now more than qualified to share his knowledge with others.

Krzysztof Ciombor

As we move towards an era where oil will likely become less accessible or even regulated in some way due to global warming concerns and other issues such as pollution caused by fuel sources like coal fired power plants, 

electric vehicles are to become the transport of the future.

 With such a massive shift across all transportation branches, all hands on deck in terms of innovative solutions are needed.

Luckily, such industry ameliorations can be observed in every aspect there is to eMobility. From ever-enhancing electric cars with prolonged-battery lives to all kinds of charging facilities, eMobility is entering a whole new level.

Amongst these solutions, a big part is played by software and digital products. Namely, eRoaming, connected car data and smart charging are all here to stay and are only advancing at a speedy pace.

We have already covered eRoaming in one of our downloadable PDFs. To see more click 

A few definitions can be found in terms of what smart charging really is. Some of the widely circulating ones say:

Smart charging is a cloud-based technology that makes it possible to adjust how much energy is used by EVs based on the current state of the energy grid.

But what does it really mean in practice? One must look at smart charging as a complex, inter-connected ecosystem that enables real-time data exchange between:


Through smart charging, the charging stations may monitor, manage, and restrict the use of charging devices to optimize energy consumption. The optimization happens on the basis of collected data which gathers information such as:

renewable energy availability or lack thereof

Future-proof nature of smart charging allows for free-choice maneuvers in terms of the quality and quantity of features, leaving the room for any necessary add-ons. All that to ensure EVs will not pose a threat to the grid in times of high charging demand that’s likely to grow directly proportional to the growing popularity of electric cars.

careful monitoring of the energy consumption and thus, transferring the charging loads across available energy sources and adjusting the power accordingly. 

The shifts are to ensure the continuity of (untouched) energy flow for its other consumers, such as homes and facilities nearby.

All about Smart Charging

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

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!

Plug and charge - a seamless charging experience.

21 JULY 2022 • 7 MIN READ