As the electric vehicle (EV) industry rapidly expands, the technologies that support it must keep pace to deliver convenience, reliability, and safety. One of the most important advancements in recent years has been the development of ISO 15118, an international standard that governs bi-directional digital communication between EVs and charging stations.
This standard plays a vital role in enabling Vehicle-to-Grid (V2G) technology and, more prominently, the Plug & Charge feature. Plug & Charge allows an EV driver to simply insert the charging plug into the car, let the system authenticate and start charging automatically, and then drive away when ready—without needing to swipe a card, use a mobile app, or enter a PIN code.
At its core, ISO 15118 defines a secure, encrypted communication process between the vehicle and the charging infrastructure. This ensures that both authentication and billing occur seamlessly and automatically in the background, making EV charging as effortless as possible for the driver.
ISO 15118, officially titled “Road Vehicles – Vehicle to Grid Communication Interface”, is an internationally recognized standard jointly developed by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). It defines an advanced, IP-based communication protocol between electric vehicles (EVs) and charging stations, known in the standard as the Supply Equipment Communication Controller (SECC) or Electric Vehicle Supply Equipment (EVSE).
The primary purpose of ISO 15118 is to create a seamless, secure, and intelligent link between EVs and charging infrastructure, enabling next-generation charging features such as Plug & Charge (PnC), Smart Charging, and Vehicle-to-Grid (V2G) integration. By standardizing communication, ISO 15118 allows EVs and charging stations to exchange data in real time, ensuring interoperability across different manufacturers and charging networks.
With Plug & Charge, drivers can start a charging session simply by connecting the cable—authentication and payment occur automatically in the background. Smart Charging optimizes energy usage, while V2G enables bi-directional power flow, allowing EVs to supply energy back to the grid.
Ultimately, ISO 15118 enhances user convenience, improves charging efficiency, and plays a key role in building a secure, interconnected, and future-ready EV charging ecosystem.
Bi-directional communication – Supports V2G, allowing vehicles to either charge from the grid or discharge stored energy back to the grid.
Automatic authentication – Replaces the need for manual steps like scanning RFID cards or entering codes.
Secure transactions – Uses advanced encryption and cryptographic certificates to protect sensitive data.
Simplified driver experience – Reduces charging initiation to a single action: plugging in the cable.
ISO 15118 supports both AC charging and DC fast charging, and it is designed to be compatible with a wide variety of charging hardware. The standard also accommodates both private and public charging infrastructure, enabling uniform operation across different brands and locations.
The Plug & Charge process is perhaps the most consumer-friendly feature enabled by ISO 15118.
Here’s how it works step-by-step:
The driver plugs the charging cable into the vehicle.
No card swipes, app interactions, or button presses are required.
A digital certificate embedded in the EV communicates with the charging point.
This certificate is part of a secure Public Key Infrastructure (PKI) system that validates the identity of the vehicle.
The charging station confirms the vehicle’s identity with the Charging Point Management System (CPMS) in the backend.
Once authenticated, the system automatically approves the charging session.
The charging process begins, with the EV and charging station exchanging status updates in real time.
Payment is handled automatically using the information associated with the vehicle’s digital certificate.
Once charging is complete or the driver stops the process, the cable is unplugged, and the session ends—again, without any extra steps.
This approach eliminates the common frustrations drivers face today, such as fumbling with RFID cards, dealing with non-functional apps, or remembering PIN codes.
Security is a critical aspect of EV charging, especially when financial transactions and sensitive user data are involved. ISO 15118 addresses this with robust cryptographic measures:
Encryption – All communication between the EV and charging station is encrypted to prevent eavesdropping.
Authentication – Both the EV and the charging station verify each other’s identities using digital certificates.
Data Integrity – Message authentication codes ensure that data cannot be altered in transit without detection.
By using PKI, the same technology that secures online banking and e-commerce, ISO 15118 ensures that only trusted vehicles and charging points can communicate.
While ISO 15118 governs the direct communication between the EV and the charging station, the data from these interactions must also be shared with the central management system operated by the Charge Point Operator (CPO). This is where the Open Charge Point Protocol (OCPP) comes into play.
OCPP is an open standard for communication between a charging station and the central backend system. It handles tasks such as:
Authenticating new users
Tracking energy consumption
Executing remote commands (e.g., start/stop charging)
Reporting maintenance issues
Limited to basic functions like starting or stopping a charging session.
Introduces Smart Charging features, allowing operators to send charging schedules and limits to the station.
Widely adopted today and compatible with most commercial charging networks.
Adds richer data exchange, including the ability for the charging station to transmit the exact requested energy amount from the EV to the backend system.
Enables more precise load management and integration with ISO 15118’s V2G and Plug & Charge capabilities.
The synergy between ISO 15118 and OCPP 2.0 unlocks the full potential of intelligent charging.
With ISO 15118 alone: The EV tells the charging station how much energy it wants.
With OCPP 2.0: The charging station can forward that precise request to the backend system, enabling accurate load planning and optimized energy distribution.
For example, if multiple EVs are plugged into a charging hub during peak hours, the backend can prioritize charging based on factors like:
Battery state of charge (SoC)
Driver’s expected departure time
Grid conditions and electricity pricing
This ensures that energy delivery is efficient, fair, and cost-effective.
Seamless Plug & Charge experience
Faster initiation of charging sessions
Automatic, transparent billing
Improved operational efficiency
Enhanced security and fraud prevention
Better integration with smart grid and demand response programs
Access to accurate energy demand data
Improved load balancing
Greater flexibility in integrating renewable energy sources
Despite its benefits, ISO 15118 adoption faces several challenges:
Many existing charging stations only support OCPP 1.6 or lower and may need hardware upgrades to work with ISO 15118 and OCPP 2.0.
The Plug & Charge PKI system requires secure issuance, renewal, and revocation of certificates, which can be complex.
Different regions and operators may implement the standard differently, potentially impacting interoperability.
Upgrading infrastructure to support these standards requires investment in both software and hardware.
The adoption of ISO 15118 is expected to grow as the EV market matures and demand for a more convenient charging experience increases. In the long run, widespread implementation will:
Standardize charging procedures globally
Support advanced V2G applications where EVs can supply power back to the grid
Enable dynamic pricing models based on real-time grid conditions
Improve overall customer satisfaction and adoption rates of electric vehicles
Automakers are increasingly building ISO 15118 support into their EVs, and more CPOs are upgrading their infrastructure to match. As OCPP 2.0 adoption accelerates, the synergy between these two protocols will form the backbone of next-generation EV charging networks.
ISO 15118 represents a major step forward in simplifying and securing the EV charging process. By enabling Plug & Charge, the standard removes the friction of manual authentication and payment, making charging as simple as connecting the cable. When paired with OCPP 2.0, it delivers precise energy management capabilities, supports smart charging, and facilitates advanced V2G integration.
As EV adoption continues to rise worldwide, these standards will play a crucial role in building a sustainable, user-friendly charging infrastructure that benefits drivers, operators, and energy providers alike. The road ahead for EV charging is faster, smarter, and more connected—and ISO 15118 is one of the key technologies steering it there.
