ISO 15118: How Plug & Charge Works

Plug in the cable, charging starts — no card, no app. We explain the PKI infrastructure and certificate chain behind ISO 15118 in plain language.

What is Plug & Charge?

Plug & Charge (PnC) lets the driver start charging and pay automatically by simply plugging in the cable — no RFID card or mobile app required. This feature is defined within the ISO 15118-2 standard.

How Does the PKI Work?

The system is built on a Public Key Infrastructure (PKI). Each EV holds an OEM certificate assigned by the manufacturer. The charge point uses a trusted EMSP (E-Mobility Service Provider) certificate hierarchy to verify it.

  1. Vehicle → SECC connection: Cable is plugged in; ISO 15118 handshake starts.
  2. Certificate exchange: The vehicle presents its OEM certificate; the SECC (Supply Equipment Communication Controller) verifies it.
  3. Contract certificate: The vehicle receives an encrypted contract certificate from the EMSP, defining who it is and which tariff applies.
  4. Authorisation: Approval is completed; energy transfer begins.

What Does ISO 15118-20 Add?

ISO 15118-20 (2022) is the successor to 15118-2 and adds protocol support for Bidirectional Power Transfer (BPT) — i.e. vehicle-to-grid (V2G) energy flow. It also brings AC Plug & Charge into scope.