ISO 15118 Explained: Plug & Charge, Smart Charging and V2G

What is ISO 15118?

ISO 15118 is a family of international standards for high-level communication between an electric vehicle and charging equipment. It lets the car and charger exchange more than a basic start or stop signal. They can share identification, charging needs, energy limits, schedules and, where supported, instructions for power to flow back out of the vehicle.

That makes ISO 15118 important to three related functions: Plug & Charge, smart charging and vehicle-to-grid (V2G). It does not provide any of them by itself. A complete service still needs compatible vehicle hardware and software, a suitable charger, backend support, certificates, energy controls and the necessary grid permissions.

Where ISO 15118 sits in the charging system

ISO 15118 covers the link between the vehicle and charging station. OCPP covers the separate link between the charging station and a charge point management system (CPMS or CSMS). The two standards therefore complement one another.

• The vehicle knows its battery limits, required energy and departure needs.
• The charging station communicates with the vehicle and applies safe power limits.
• The CPMS or CSMS authorises sessions, manages certificates and coordinates charging across sites.
• An energy-management system or aggregator may add tariffs, building demand, solar generation and flexibility-market signals.

OCPP 2.0.1 supports ISO 15118-2 functions including Plug & Charge and advanced smart-charging inputs. OCPP 2.1 adds support for ISO 15118-20 and bidirectional energy flow. Protocol support in a specification still needs to be implemented and tested across the actual charging system.

How does Plug & Charge work?

Plug & Charge allows a compatible EV to identify and authorise itself after the cable is connected. The vehicle presents a contract certificate. The charger and backend use a public-key infrastructure to check whether that certificate is valid and linked to an eligible charging contract. If it is, the session can start without an RFID card, payment app or manual account selection.

The convenient bit is visible to the driver. Most of the work is not. The vehicle, charger, CPMS, mobility-service contract and certificate chain must all agree. A charger with an ISO 15118 communications module is therefore not automatically a live Plug & Charge service.

How ISO 15118 improves smart charging

Basic smart charging can work without ISO 15118. A CPMS can already delay a session or limit current using site capacity, tariffs or a fixed schedule. ISO 15118 adds better information from the vehicle itself, such as the requested amount of energy and anticipated departure time.

That can replace a rough assumption with a more accurate charging plan. A depot can prioritise a van that needs 60 kWh before 06:00 over a car that needs 10 kWh by lunchtime. The CPMS or energy-management system still makes the operational decision. ISO 15118 supplies a communication path; it does not choose the tariff, run the building or guarantee the lowest-cost outcome.

What does ISO 15118-20 add for V2G?

ISO 15118-20:2022 defines the communication messages and sequences needed for bidirectional power transfer. This is a major step for vehicle-to-grid, vehicle-to-home and vehicle-to-building services because the car and charger need to agree when energy may leave the battery, how much power is available and when that flow must stop.

ISO also published Amendment 1 in 2026, covering AC distributed-energy-resource services, Megawatt Charging System services and an improved security concept. Procurement documents should name the required edition and amendment rather than treat “ISO 15118 ready” as a single, universal capability.

Communication is only one part of V2G. The vehicle must permit discharge. The charger and installation need suitable two-way power electronics, protection and metering. The backend needs to coordinate charging and export, while an energy provider or aggregator may handle market participation. Local network rules and commercial agreements must also allow it.

How AFIR relates to ISO 15118

The EU Alternative Fuels Infrastructure Regulation (AFIR) requires qualifying publicly accessible recharging points built or renovated from 13 April 2024 to be capable of smart recharging. AFIR does not require every charger to provide V2G, nor does it make ISO 15118 the only route to smart charging. It does increase the value of chargers and management systems that can exchange data and respond to external instructions.

What CPOs should check before procurement

• Which ISO 15118 version is supported in hardware and active firmware?
• Which vehicles and charging modes have been tested?
• Who provides the Plug & Charge contracts, certificates and lifecycle management?
• Can the CPMS use the required smart-charging data, and which OCPP version does it support?
• What extra equipment, metering, protection and grid approval would bidirectional operation require?

These questions separate a useful upgrade path from a feature label that cannot yet be operated.

How amina C2 and M2 fit

amina C2 fits CPO deployments where quick installation, dependable connectivity and direct backend integration matter. It combines LTE Cat 1 bis, dual-band Wi-Fi, local OCPP 1.6J, RFID and over-the-air updates. Its hardware is prepared for ISO 15118-20, Plug & Charge and bidirectional charging, while the final service depends on the surrounding vehicle, firmware, CPMS and energy setup.

amina M2 applies the same hardware-readiness to sites where energy must also be measured and managed locally. Its MID-certified meter, Ethernet, Modbus RTU and local load balancing suit apartments, workplaces and fleets where billing, reimbursement and site capacity are part of the operational brief.

Both products follow the same principle: focused charging hardware should work with specialist software and energy partners, without forcing the operator through an unnecessary proprietary layer.

Frequently asked questions

Does ISO 15118 mean a charger supports V2G?

No. ISO 15118-20 provides the communication needed for bidirectional power transfer. The vehicle, charger power electronics, installation, backend and grid arrangement must also support it.

Does ISO 15118 replace OCPP?

No. ISO 15118 connects the vehicle and charger. OCPP connects the charger and CPMS. Advanced charging services often need both links.

Can Plug & Charge work with OCPP 1.6?

The Open Charge Alliance provides an application-note route for Plug & Charge certificate messages over OCPP 1.6 DataTransfer. It does not include ISO 15118 smart-charging functionality. OCPP 2.0.1 provides native support for ISO 15118-2 functions, while OCPP 2.1 extends this to ISO 15118-20 and bidirectional charging.