ISO 15118 and Plug & Charge: A Technical Deep Dive
The Short Answer
ISO 15118 is the international standard for high-level communication between an EV and EVSE. It enables Plug & Charge (PnC) — automatic authentication and billing without RFID or app — and Vehicle-to-Grid (V2G) energy flow. ISO 15118-20 (2022) extends support to AC bidirectional charging and 5G-ready high-power sessions.
The J1772 Control Pilot signal handles basic EV-to-EVSE handshaking. ISO 15118 goes far beyond that — it is a full digital communication stack that enables encrypted authentication, automatic billing, smart charging schedules, and bidirectional energy flow, all over the same charging cable.
ISO 15118 is an international standard defining the communication protocol between an EV and an EVSE over the Power Line Communication (PLC) layer of the charging cable. It enables: Plug & Charge (automatic authentication using vehicle certificates), smart charging negotiation, and Vehicle-to-Grid (V2G) bidirectional power flow. ISO 15118-2 covers DC and AC charging; ISO 15118-20 adds bidirectional AC and enhanced power management.
The ISO 15118 Communication Stack
| Layer | Technology | Function |
|---|---|---|
| Physical | HomePlug GreenPHY (PLC on Control Pilot wire) | Modulate data onto the CP conductor at 4–7 Mbps |
| Network / Transport | IPv6 + TCP/TLS | Encrypted, authenticated IP communication |
| Session | V2G Transfer Protocol (V2GTP) | Message framing and session management |
| Application | ISO 15118 XML/EXI messages | Charge parameters, PnC certificates, energy schedules |
Plug & Charge (PnC) Authentication Flow
When a PnC-capable EV plugs into a PnC-enabled EVSE: 1) PLC link is established on the CP wire → 2) TLS handshake using EVSE and vehicle certificates → 3) Vehicle presents its eMAID (EV Contract Certificate) → 4) EVSE validates certificate against the Mobility Operator (MO) PKI trust chain → 5) Authorization granted → 6) Charging begins automatically. No RFID card, no app, no manual step required.
PKI Infrastructure for Plug & Charge
PnC requires a Public Key Infrastructure (PKI) involving: the OEM Provisioning CA (issues vehicle certificates at the factory), the Mobility Operator CA (issues charging contracts), and the CPO Root CA (issues EVSE certificates). The Hubject Intercharge platform and ChargeX consortium provide open PKI clearinghouses enabling multi-network PnC roaming.
ISO 15118-20: What's New
- Bidirectional AC charging (V2G and V2H on AC Level 2) — enables home energy arbitrage
- Dynamic energy management: vehicle and EVSE negotiate optimal charge schedule in real time
- Wireless PLC alternative via ISO 15118-8 (Wi-Fi based HLC for wireless charging pads)
- Enhanced security: stricter certificate lifecycle management and revocation
- Multi-charge point sessions for scheduled charging at multiple stations
V2G (Vehicle-to-Grid) Technical Requirements
V2G Requires Bidirectional EVSE and a Smart Inverter
V2G is not just software — the EVSE must include a bidirectional power electronics module, and the vehicle must have a bidirectional onboard charger (OBC). Most current EVs are unidirectional. Nissan LEAF (CHAdeMO), Ford F-150 Lightning, and select others support V2G/V2H as of 2026. NACS-based bidirectional charging is emerging under ISO 15118-20.
What EVSE Installers Need to Know
- ISO 15118 / PnC EVSE requires internet connectivity for PKI certificate validation — reliable WAN is mandatory
- OCPP 2.0.1 is required for CSMS to exchange PnC certificate management messages (ISO 15118 CertificateInstalled action)
- V2G-capable EVSE requires utility interconnection approval and may require UL 1741-SA listed equipment
- PnC is transparent to circuit design — wiring and load calculations are unchanged
- Specify ISO 15118-2/20 compliance in commercial RFPs; not all 'smart' chargers support it
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Frequently Asked Questions
Does my EV support ISO 15118 Plug & Charge?
As of 2026, ISO 15118 PnC is supported by Porsche Taycan, Audi e-tron, Hyundai Ioniq 5/6, Kia EV6, BMW iX, and growing. Tesla supports a version of PnC on its Supercharger network. Ford F-150 Lightning supports V2H. Check your vehicle's spec sheet for 'ISO 15118' or 'Plug & Charge' support.
Is ISO 15118 required for Level 2 EV chargers?
Not universally — most Level 2 EVSE still use basic J1772 CP signaling. ISO 15118 is primarily found in commercial DC fast chargers and premium networked Level 2 units. However, ISO 15118 support will become increasingly expected as V2G and PnC adoption grows.
Can HomePlug GreenPHY PLC interfere with other building systems?
HomePlug GreenPHY operates on the CP wire inside the charging cable, isolated from building wiring by the EVSE electronics. Interference with other building systems is rare in practice but has been reported in proximity to certain industrial equipment. Use listed EVSE from reputable manufacturers to minimize risk.
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Michael Rivera
Texas Master Electrician with 12+ years in the trade and 500+ EV charger installations. Lead instructor at EVCharger Academy.
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