Stop 01 of 08 · Roaming

Why does a card work at someone else's charger?

About 6 min · 3 questions ·

Thursday
The situation

A driver from Germany charges at a motorway site in Austria. The card in the wallet comes from a German provider; the charger belongs to an Austrian operator.

The two companies have never met in person. The card works anyway.

The questionHow can one card work at chargers of companies its provider has never dealt with directly?

Guess firstWhen was the current version of the OCPI roaming protocol, 2.3.0, released?RevealHide

On 21 February 2025. Its predecessor 2.2.1 dates from October 2021; a version 3.0 is in preparation.

One driver, many networksWithout and with roaming
Without roamingA card or app for every network.
  1. Network Acard A
  2. Network Bcard B
  3. Network Capp C
With roamingOne contract, many networks.
  1. Driverone card
  2. eMSPthe provider
  3. Roamingagreements and data
  4. CPOsmany networks

Ad hoc payment without a contract remains possible at public chargers; roaming adds the convenience of one card everywhere.

Two roles, one session

  • The charge point operator () runs the charger and sells the charging.
  • The e-mobility service provider () holds the driver's contract, issues the card or app and sends the invoice.

connects the two. , the Open Charge Point Interface, enables an automated roaming setup between them: authorisation, information about chargers including live status, session records, remote commands and information.

OCPI in four datesA protocol that keeps moving
OCPI 2.2Hubs

added support for roaming hubs and parties with several roles

OCPI 2.2.12021

final release on 6 October 2021

OCPI 2.3.02025

released 21 February 2025, for new EU rules

OCPI 3.02027

draft, release targeted around mid-2027

From the OCPI version history and the EVRoaming Foundation, which manages the protocol and keeps it freely available.

Check your understanding

3 questions. Answer all of them to complete this stop. Each answer explains itself.

01Question 1 of 3

Which role issues the driver's card and sends the invoice?

02Question 2 of 3

What does OCPI connect?

03Question 3 of 3

What does roaming mean in EV charging?

Further in other paths

  1. EV charging fundamentals · Stop 02Who are all the companies involved?Look closely at one charging moment and count the companies at work: site host, CPO, eMSP, software provider and grid operator.
  2. Business models · Stop 03How does an eMSP earn money?Contract prices, subscriptions and the cost of roaming: how an e-mobility service provider earns between what drivers pay and what operators charge.
  1. EVRoaming Foundation: OCPI 2.3.0, introduction and background. https://github.com/ocpi/ocpi/blob/2.3.0/release/core/introduction.asciidoc. Checked 09 Oct 2026.
  2. EVRoaming Foundation: OCPI version history. https://github.com/ocpi/ocpi/blob/2.3.0/release/core/version_history.asciidoc. Checked 09 Oct 2026.
  3. EVRoaming Foundation: OCPI background: versions, standardisation and adoption. https://evroaming.org/ocpi-background/. Checked 09 Oct 2026.
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