Climbing the API mountain of electric vehicle charging

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Written by Micha Roon and Christopher Burgahn

View the original medium article here.

Did you know that by opening this website, you have initiated at least 30 requests between your device and the servers of Whilst most people would consider this information as abstract or even irrelevant, the number of necessary requests defines how fast you can start reading this article (amongst other factors). Professional marketeers would consider 30 requests as quite good and most users would confirm by stating that opens quite fast. Of course, in the first place all of this is made possible by the use of up-to-date hardware (server, computer, wires, etc.) and well-written software programs (operating system, browser, etc.). However, in a world of more connected services none of this would work without efficiently connecting all software programs with each other (How much sense would a Medium website have if it is not reachable from all over the world, 24/7?). This is made possible by the implementation of so-called APIs.

But let’s leave the example of this website aside and talk about another industry that you as a reader of this article might be even more interested in. Charging of battery electric vehicles (EV). The exciting part of EVs is of course driving them, but if you like innovative technology then you have many reasons to be even more excited. The potential of digital use-cases that can be implemented with EVs is simply amazing — not only because cars become increasingly digitized themselves, but also because the electricity that they usually need for driving can be used for many other things as well (storing renewable energy, electrifying your house, balancing the grid, etc.).

For EV drivers the most important use-case based on API connections is EV roaming — but we can’t stop there

One of the highly crucial use-cases for EV drivers is of course charging an EV wherever you go — a concept called EV roaming. To let drivers charge with one favorite payment method / smartphone app / RFID card at any station in a given market, you must connect all these sub-charging networks and combine them into one. From a technical standpoint this is a typical API problem: many Charge Point Operators (CPO) and eMobility Service Providers (eMSP) wanting to connect their computer systems for sending around location data, authorization data, charging sessions and billing information. Over the last years the EV charging industry did a great job and the problem is (mostly) resolved with many options available for connecting APIs for EV roaming (Hubs, P2P, Decentralized).

One could say that the EV charging industry can stop there as EV drivers can charge wherever they want to go. But being passionate EV drivers ourselves, we dare to speak for all our E-Mobility fellows out there (especially for the ones to come who might not be so forgivable): No, we want more! We want to optimize the charging session to get lower prices, we want to know which charging station has the best ice cream parlor next to it, we want to know whether the electricity charged is green, we want the ability to reserve a charge point, etc. And guess what? All these use-cases are based on connecting many different IT systems with one another — with the use of APIs.

The API Mountain of EV charging

Connecting APIs of CPOs and eMSPs for implementing the EV roaming use case was therefore only the beginning of many API connections for creating a best-in-class user experience for the mass market audience. Services that you may want to integrate include billing, payment, POI data enrichment, green electricity certificates and many more. Each of which use a different API. For product managers and software development teams in EV charging this might end up in a never ending effort in making and maintaining API connections. A challenge that we call the API mountain of EV charging.

To get an understanding of the complexity that the whole EV industry is facing we recommend having a look at this overview of the “Flexible E-Mobility reference architecture”. It was created by ECISS, a collaborative project between Allego, Eneco, Greenflux, Jedlix, TNO and NKL. It provides a useful overview of all the services that could already be implemented.

Three tips for climbing the API mountain of EV charging

Now, what? Luckily, you are not alone in the endeavors of climbing the API mountain and there are some things that you could consider throughout your journey to the very top. Our top-3 tips can make your life much easier:

  1. Walk and learn with others
    Self-explanatory. Sharing your learnings with others and learning from others is essential, especially in a market where the technology is evolving so fast. Joining organizations like the EV Roaming Foundation, Open Charge Alliance or the Share&Charge Foundation help you to learn as fast as possible.
  2. Build on open protocols and open source software
    In our opinion it is highly important to implement APIs using open protocols (OCPP, OCPI, etc.) and best, open source software (like the Open Charging Network [OCN]). As discussed in this article the internet community benefited highly from using open protocols. As EV charging community we should do the same. By using the same open source tools to implement these protocols we can achieve even more.
  3. Get the most out of existing APIs
    We think the APIs that are in the market are pretty advanced already and there are many use-cases that can be implemented using existing APIs. For example: Why not using an OCPP broker as proposed here to easily route OCPP messages to other services? Or using OCPI for implementing a smart charging use case?

As tip 1) and 2) in our opinion are taken into account by many companies in EV charging already, in this article series we want to explain what we mean with tip 3) “Get the most out of existing APIs”. We see a big potential for massive cost savings in development costs simply by using existing OCPI APIs for advanced use-cases: For example, implementing a settlement service between CPO and eMSP based on OCPI Charge Details Records. The upcoming OCN Service Interface will make this possible — for anyone using the OCN for EV roaming just by a simple click. In the next article, we will talk about how. Stay tuned for more.

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