How does the certificate get into the car?
The driver signed the provider's contract in an app three months ago. At its next session, the car received the certificate through a charger and has carried it ever since.
Before the certificate expires, the car will ask for an updated one at a charger.
The questionHow does a certificate reach the car, and how is it renewed?
The car sends a certificate installation request to the charger, over the ISO 15118 connection.
Select each step to see who does what. As described in the OCA application note for OCPP 1.6.
The charger as a courier
The application note of the Open Charge Alliance describes it like this: the car sends a certificate installation request to the charger; the charger sends a request to its backend with the action install or update; the backend retrieves the right certificate and responds. The charger passes the certificate on; it does not create it. The private key that belongs to a new travels only encrypted, so that intermediaries cannot read it.
The charger needs its own certificate too. It requests it from its backend with a signing request, and the backend returns a signed certificate.
OCPP versions and Plug & Charge
- 2.0.1 supports authorisation and all functions to install and update certificates.
- OCPP 1.6 does not support ISO 15118 messages; an application note of the Open Charge Alliance makes Plug & Charge possible by wrapping the 2.0.1 messages in data transfers.
Check your understanding
3 questions. Answer all of them to complete this stop. Each answer explains itself.
What role does the charger play in installing a contract certificate?
The charger acts as a courier between car and backend; it does not create the certificate.
Does OCPP 1.6 support ISO 15118 messages natively?
The application note wraps OCPP 2.0.1 messages in DataTransfer to bring Plug & Charge to 1.6.
How does a charger obtain its own certificate?
The charger requests its certificate from its backend, which returns it signed.
- OCPP Open Charge Point Protocol: the open protocol between a charger and its operator's backend. EV charging fundamentals, stop 03 Glossary
- ISO 15118 International standard for the digital communication between car and charger, the basis of Plug & Charge. EV charging fundamentals, stop 08 Glossary
- Plug & Charge The car identifies itself with a certificate when plugged in, so no card or app is needed. EV charging fundamentals, stop 08 Glossary
- Contract certificate A certificate in the car that binds the driver's contract ID to a key pair whose private half the car keeps, used for Plug & Charge. Stop 03 Glossary
- Open Charge Alliance: Using ISO 15118 Plug & Charge with OCPP 1.6, application note v1.0, 2020. https://openchargealliance.org/wp-content/uploads/2025/05/ocpp_1_6_ISO_15118_v10-3.pdf. Checked 09 Oct 2026. Licence: CC BY-ND 4.0.
- ISO: ISO 15118-2:2014, Vehicle-to-Grid Communication Interface, Part 2: Network and application protocol requirements. https://www.iso.org/standard/55366.html. Checked 13 Oct 2026.
- Open Charge Alliance: Using ISO 15118 Plug & Charge with OCPP 1.6, application note v1.0, 2020. https://openchargealliance.org/wp-content/uploads/2025/05/ocpp_1_6_ISO_15118_v10-3.pdf. Checked 09 Oct 2026. Licence: CC BY-ND 4.0.
- Open Charge Alliance: What is new in OCPP 2.0.1? Whitepaper, version 1.0, March 2023. https://openchargealliance.org/wp-content/uploads/2024/01/new_in_ocpp_201-v10.pdf. Checked 09 Oct 2026. Licence: CC BY-ND 4.0.
- Open Charge Alliance: Using ISO 15118 Plug & Charge with OCPP 1.6, application note v1.0, 2020. https://openchargealliance.org/wp-content/uploads/2025/05/ocpp_1_6_ISO_15118_v10-3.pdf. Checked 09 Oct 2026. Licence: CC BY-ND 4.0.