ISO 15118 is an international standard defining secure, digital communication between an Electric Vehicle (EV) and a charging station (EVSE). It replaces older analog signaling with encrypted, IP-based communication over the charging cable or wirelessly. The standard enables Plug & Charge, smart charging, and bidirectional energy transfer, laying the foundation for automated, secure, and flexible EV charging experiences.
What Cars Support ISO 15118?
Most modern EVs from major manufacturers now support ISO 15118, particularly Plug & Charge features. Support varies by region and model year.
OEM Adoption and Examples
- European brands: BMW, Mercedes-Benz, Volkswagen, Audi, Porsche, and Volvo widely implement ISO 15118 for AC and DC charging.
- North American brands: Ford and GM EV models offer partial ISO 15118 support, often limited to Plug & Charge.
- Asian brands: Nissan and Hyundai/Kia implement ISO 15118 mainly in newer EV models with smart charging and Plug & Charge capabilities.
Key Considerations
- ISO 15118 support depends on both vehicle software and EVSE compatibility.
- Some vehicles may support ISO 15118-2 but not the advanced ISO 15118-20 features like bidirectional charging.
- Vehicle firmware updates can enable or improve ISO 15118 functions post-production.
What is the IEC 61851 Standard?
IEC 61851 is an older international standard for electric vehicle charging that primarily defines analog and basic digital signaling for AC and DC charging. It does not include secure, automated authentication or smart energy management features.
Overview of IEC 61851
- Focuses on PWM (Pulse Width Modulation) control for AC charging.
- Supports simple charging current negotiation but lacks smart charging or V2G capabilities.
- Used widely before ISO 15118, especially in public AC charging infrastructure.
Limitations Compared to ISO 15118
- No Plug & Charge support.
- Limited or no bidirectional charging.
- Minimal security features; communication is mostly unencrypted.
What is the Difference Between ISO 15118 and ISO 15118-20?
ISO 15118-20 is the second-generation protocol extending ISO 15118-2 with advanced security, wireless charging support, and bidirectional energy transfer capabilities.
Key Differences
| Feature / Metric | ISO 15118-2 | ISO 15118-20 |
|---|---|---|
| Plug & Charge | Yes | Yes |
| Security | One-way TLS | Mutual TLS with advanced cryptography |
| Charging Types | AC, wired | AC, wired, wireless, pantographs |
| Smart Charging | Basic negotiation | Advanced negotiation including grid-aware scheduling |
| Bidirectional Charging | Not supported | Supports V2G, V2H, V2B scenarios |
| Authentication | Vehicle authenticates EVSE | Vehicle and EVSE authenticate each other |
Practical Implications
- ISO 15118-20 allows full bidirectional power flow and mutual authentication, enabling EVs to act as distributed energy resources.
- EVSE supporting ISO 15118-20 can coexist with ISO 15118-2 systems, but full functionality depends on vehicle and network compatibility.
What is the Difference Between ISO 15118 and IEC 61851?
ISO 15118 is a modern, encrypted digital protocol with Plug & Charge, smart charging, and bidirectional energy support. IEC 61851 is an older standard using analog or basic digital signaling, with limited automation and no inherent security.
Comparison Table
| Feature / Metric | IEC 61851 / DIN SPEC 70121 | ISO 15118-2 | ISO 15118-20 |
|---|---|---|---|
| Plug & Charge | No | Yes | Yes |
| Smart Charging | Minimal | Basic scheduling | Advanced, grid-aware |
| Security | None | TLS (one-way) | Advanced Mutual TLS |
| Charging Types | AC wired | AC wired | AC wired, wireless, pantographs |
| Bidirectional Energy | No | No | Yes (V2G, V2H, V2B) |
Operational Context
- IEC 61851 remains relevant in legacy charging networks and simple AC EVSE installations.
- ISO 15118 is now required in EU public AC charging points (AFIR) and US federally funded networks (NEVI), representing the future-proof standard.
ISO 15118 Implementation Requirements for EV Chargers
ISO 15118-2 Requirements
Communication & Connection Capabilities (Mandatory)
- Power Line Communication (PLC) support
- SLAC pairing for vehicle-EVSE matching
- Session establishment, maintenance, and termination
- SECC operation on EVSE
Charging Session & Control Functions (Mandatory)
- Service discovery
- AC charging parameter negotiation (current, phases, power limits)
- Start/stop control of charging
- Session termination and resource release
Plug & Charge (Protocol Layer Support)
- TLS secure communication channel
- Certificate validation and management
- Contract certificate installation process
Non-Mandatory Features
- Bidirectional charging (V2G/V2H)
- Advanced metering or billing
- Energy management beyond basic control
ISO 15118-20 Requirements
Communication & Session Capabilities (Mandatory)
- ISO 15118-20 session state machine support
- AC charging service discovery and negotiation per -20 definitions
- Backward compatibility with ISO 15118-2
Plug & Charge Support (Mandatory)
- TLS security and certificate management
- Plug & Charge message flow support
Bidirectional Power Transfer (Optional)
- V2G / V2H / V2L scenarios supported at protocol layer
- Implementation depends on hardware, grid regulations, and product planning
Current Regulatory Context
European Union (AFIR / Regulation EU 2023/1804)
- ISO 15118-2 mandatory for public AC charging points from 2026
- ISO 15118-20 mandatory for public and private AC charging points from 2027
United States (NEVI Program)
- Federally funded highway chargers must comply with ISO 15118 for standardized Plug & Charge experience
Impact for CPOs and Manufacturers
- EVSE and vehicle manufacturers must ensure hardware and software compliance
- Standardization improves user experience, interoperability, and future-proofing for smart grids
FAQ
What is Plug & Charge?
Plug & Charge allows an EV to automatically authenticate, authorize, and pay for charging without external apps, RFID, or cards, using digital certificates.
Can ISO 15118 work with wireless or inductive charging?
Yes, ISO 15118-20 adds support for wireless charging and pantograph connections, enabling flexible deployment options.
Does ISO 15118 require bidirectional charging?
No, bidirectional energy transfer is optional. ISO 15118-20 defines it at the protocol level, but implementation depends on hardware and regulatory conditions.
How does ISO 15118 improve security?
ISO 15118 uses TLS encryption, certificate-based authentication, and in -20, mutual authentication to prevent spoofing or unauthorized charging.
Are all EVs ISO 15118 compatible?
Not all. Compatibility depends on OEM, model year, and firmware. Many newer EVs in Europe and North America support at least ISO 15118-2.
How does ISO 15118 differ from IEC 61851?
ISO 15118 is digital, secure, and supports Plug & Charge, smart charging, and bidirectional energy. IEC 61851 is analog, with minimal automation and limited security.
Conclusion
ISO 15118 transforms EV charging with secure, automated, and smart communication, enabling Plug & Charge, smart load management, and future-ready bidirectional energy solutions.
