Comparateur de bornes de recharge et systèmes de gestion Bidirectional charging - Comparateur de bornes de recharge et systèmes de gestion

Abbreviations

A = Ampere
AC = Alternating Current
API = Application Programming Interface
CPO = Charging Point Operator
DC = Direct Current
EMS = Energy Management System
eMSP = eMobility Service Provider (providing e-mobility card to users in order to charge across Europe on public charging stations)
HEMS = Home Energy Management System
GPRS = General Packet Radio Service
kW = kilowatt
kWh = kilowatt-hour
MID = Measuring Instruments Directive
OCPP = Open Charge Point Protocol
OCPI = Open Charge Point Interface
RFID = Radio-frequency Identification
TAB = Technical connection conditions, which define the technical standards for connecting to the electricity grid in Luxembourg (Technische Anschlussbedingungen)
VDC = Volt Direct Current
V2H = “Vehicle-to-Home” (from the vehicle to the house / building)
V2G = “Vehicle-to-Grid” (from the vehicle to the electricity grid)
V2L = “Vehicle-to-Load” (from the vehicle to power external electronic devices)
V2X = “Vehicle-to-Everything” (umbrella term covering all forms of bidirectional charging)

AC charging station

AC (Alternating Current) charging stations charge with alternating current. The power of an AC charging station can vary between 3.7kW and 22kW. The alternating current passing through the charging station must be transformed into direct current to charge the battery of an electric vehicle. It is transformed using an AC/DC converter located in the electric vehicle.

Access control

To protect access to charging stations, there are different types of access control, such as RFID badge readers, smartphone applications, QR-code scanners, etc. This prevents unauthorized users from charging for free.

Backend

A backend is a management platform on which the data from intelligent charging stations is hosted, with different functionalities depending on the service provider. For example, you can view your charging infrastructure, control the charging station in real time, manage access and users on the charging infrastructure, or bill the electricity costs associated with charging electric vehicles.

Bidirectional charging

Bidirectional charging enables both the charging and discharging of electricity from an electric vehicle (EV) battery using a bidirectional charging station.

Bidirectional charging stations are available in both alternating current (AC) and direct current (DC) versions. Not all electric vehicles support bidirectional power transfer in both AC and DC, unlike conventional charging.

There are several types of bidirectional charging:

V2G (Vehicle-to-Grid): This technology enables energy stored in an electric vehicle’s battery to be fed back into the electricity grid via a bidirectional charging station.

V2H (Vehicle-to-Home): This allows energy stored in an electric vehicle’s battery to be supplied to a home’s electrical system.

V2L (Vehicle-to-Load): This allows an electric vehicle’s battery to power external electronic devices, typically via a dedicated 230 V socket on the vehicle.

V2X (Vehicle-to-Everything): This is an umbrella term that encompasses all the above functionalities. It enables energy stored in an electric vehicle’s battery to be supplied to various destinations, including the electricity grid, a home, or external electrical devices. V2X includes V2G, V2H and V2L.

Billing

Billing systems support different pricing structures:

Simple tariff: Charging sessions are billed solely on the basis of €/kWh.

Multi-variable tariff: Charging sessions are billed using a combination of pricing components (€/kWh, fixed tariff, €/minute, transaction fees, parking duration). The tariff may also vary depending on the charging station’s power rating or the time of day.

Billing management

A billing management system collects and stores information (kWh, location, charge point, user identification, date, time, start of charge, end of charge) from a charging station via the OCPP (Open Charge Point Protocol) communication protocol. To transfer data to a platform, charging stations must have access to the Internet via Ethernet, Wi-Fi or GPRS (SIM card). Management systems, also known as ‘management platforms’, can interpret charging sessions according to the needs of system users. Generally speaking, a billing management system (backend or management platform) offers:

real-time visualization of the infrastructure
view all the load sessions that have taken place
extract charging session reports
configure badges for access to the infrastructure, or even badges that can be used at public charging stations (LU and EU)
charge for charging sessions on a per-user basis
reimburse charging sessions carried out at home by employees using company vehicles
make charging infrastructure publicly accessible (CPO as a service – Charging Point Operator – usually own and operate private or public charging infrastructure)
establish simple and/or complex tariffs for access to charging stations.

Charging station nominal power

Private charging infrastructures (domestic connection for single-family homes) are in principle limited to 11 kW, which is recommended and sufficient for the home. A higher charging capacity (up to a maximum of 22 kW) requires an increase in the capacity of your domestic connection. You should also make sure that the power of the planned installation matches the technical specifications of your electric car.

Note that the comparison tool includes charging stations whose power rating can be adapted (from 22 kW to 11 kW).

Charging with surplus solar energy

Functionality for a charging station to charge an electric vehicle only when the solar production, in a self-consumption configuration, produces a surplus of electricity compared with the consumption required in the home. This feature allows you to charge your electric vehicle instead of feeding the surplus electricity back into the grid, ensuring that your vehicle is charged using local, sustainable electricity.

Collective smart charging management system

A collective smart charging management system manages all charging stations connected behind the same grid connection point in order to limit the simultaneous power demand to a level that does not exceed the capacity made available by the distribution system operator at the connection point.

The system can accommodate a number of charging points equivalent to the number of indoor and outdoor parking spaces eligible for Klimabonus subsidies for residential buildings. It also enables non-discriminatory connection of future users and the allocation of energy consumption to each charging point.

There are two types of systems:

Proprietary system: A proprietary system is designed for a specific charging station brand and generally operates only with that manufacturer’s charging stations, or even only with certain models. Some proprietary systems are integrated directly into the charging stations, while others rely on an external module supplied by the same manufacturer.
Open system: An open system enables charging stations from different manufacturers and different models to be integrated. These systems operate either via the Internet using OCPP Smart Charging or through a local external controller.

Most open systems require an IT rack that connects all charging stations to the same network switch via communication cables, allowing them to exchange information and manage the available electrical capacity behind a shared grid connection.

DC charging station

A DC (direct current) charging station charges with direct current. The power of a DC charging station can vary between 20kW and 600kW. Alternating current is transformed into direct current (AC/DC) in the DC charging station, delivering direct current directly in the electric vehicle’s battery.

Dynamic electricity tariffs

Dynamic electricity tariffs are pricing schemes within electricity supply contracts that adjust electricity prices in real time according to supply and demand, wholesale market prices or electricity availability.

These dynamic tariffs can be integrated into an Energy Management System (EMS) to optimise electricity consumption, for example by charging when market prices are low and reducing consumption during periods of higher prices.

Dynamic load management

Dynamic: this involves distributing a given amount of power fairly or unfairly (prioritisation) between several charging stations, considering the power currently available according to the building’s real-time consumption. For example, the building’s main circuit breaker is 100 A, which is equivalent to around 69 kW three-phase. With Dynamic Load Management, if the building consumes 60kW, there would only be 9 kW available for the charging infrastructure, which would be distributed between the various charging stations in use. If the building now only consumes 29 kW, there would still be 40kW available for the infrastructure. This system generally requires an additional smart meter as well as current transformers that can measure the current (A – Ampere) required by the building in real time, and this smart meter communicates the information to the charging infrastructure so that it can adapt according to the power available.

Electric vehicle communication (API)

This refers to an automotive manufacturer’s ability to communicate with an electric vehicle through its own Application Programming Interface (API). These manufacturer APIs allow third-party applications or management platforms to communicate directly with the vehicle in real time, for example to retrieve the battery’s state of charge, the vehicle’s location or to send remote commands.

Electrical protection devices for charging stations

Every charging station must be installed in accordance with good engineering practice and the technical connection requirements (TAB) established by Luxembourg’s distribution grid operators.

Some protection devices are integrated into the charging station, while others are not. In such cases, all required electrical protection devices must either be built into the charging station or installed in the electrical distribution board.

Required protection devices typically include:

Circuit breaker
Type A or Type B residual current device (RCD)
DC residual current monitor≥ 6 mA

Energy management system

Energy Management Systems make it possible to bring together different energy devices on the same platform / App for the purpose of energy optimisation. These include charging stations (AC and/or DC), storage batteries, photovoltaic panels and heat pumps.

Objectives:

manage energy devices
monitor energy consumption
allocate power, manage charging priorities, schedule deferred charging sessions.

Klimabonus 530 subsidy available from 1 October 2026.
Find out how much financial support is available at: aides.klima-agence.lu

Energy Management System (EMS):

Proprietary system: this is a system generally integrated into electrical devices (charging station, battery, inverter, heat pump) from the same manufacturer or with an external “HEMS/EMS” module specific to the brand.
Open system: this is a system capable of integrating electrical devices from different manufacturers, as far as brands are compatible with the system.

Integrated battery storage in the charging station

DC charging stations with battery storage are available on the market. These charging stations charge their batteries in alternating current at moderate power, and thanks to the accumulation of energy in the storage battery, they can deliver direct current electricity at high power directly to the battery of an electric vehicle.

Interoperability – Publicly accessible charging infrastructure

The interoperability of a charging station means that it can exchange data with any management platform using standardised communication protocols and can also receive remote commands from those platforms.

This openness is particularly important when a charging station is intended to be made publicly accessible using standardised payment methods, such as mobility cards, ad-hoc QR code payments or bank card payments.

Klimabonus subsidies

The tool clearly indicates whether a private charging station is eligible for Klimabonus financial support. Three levels of subsidy are available:

Basic charging station
Intelligent charging station
Bidirectional charging station
Find out how much aid is available depending on the type of charging station: subsidies.klima-agence.lu

Modbus RTU

Modbus RTU (Remote Terminal Unit) is a Modbus serial communication protocol designed for industrial automation systems.

In particular, it facilitates the exchange of data between various devices, such as sensors, actuators and controllers, connected to a shared communication channel.

Modbus TCP/IP

Modbus is a simple and widely used industrial communications protocol for sending data between industrial devices. Modbus TCP/IP is an adaptation of the well-established Modbus protocol for use over TCP/IP networks and allows Modbus devices to communicate via Ethernet, making it easy to connect devices over long distances or to connect to devices over a network.

TCP/IP is a data link protocol used on the Internet to allow computers and other devices to send and receive data.

TCP/IP stands for Transmission Control Protocol/Internet Protocol. It enables devices connected to the Internet to communicate with each other via networks.

Source: https://www.avg.com/fr/signal/what-is-tcp-ip ; https://www.ip-systemes.com/quest-ce-que-modbus-tcp.html#

OCPP 1.6

The Open Charge Point Protocol (OCPP) provides a uniform solution for the method of communication between the charge point and the central system. Thanks to this protocol, it is possible to connect any central system to any charge point, regardless of the supplier. A uniform standard avoids all kinds of coordination problems and is therefore an advantage for the entire electric vehicle market.

To ensure that all safety functions and features are present, version 1.6 is mandatory.

Payment system

A means of payment that is widely deployed in Europe, such as a bank card reader or a generated QR code. This has been introduced as part of the AFIR (Alternative Fuel Infrastructure Regulation) and the accessibility of public charging infrastructures.

Peak shaving

Peak shaving is an energy management technique that reduces peak electricity demand in order to avoid placing excessive strain on the electricity distribution network during periods of high demand.

This technique can significantly reduce electricity costs, particularly since the introduction of the new low-voltage electricity network tariff structure in January 2025.

Power management

Functionality enabling the user to reduce the power of a charging station either via a smartphone app or via another means accessible from the charging station. For example, when it is not necessary to charge at 11 kW, because the car is going to be parked in the same place for more than 8 hours, it is possible to reduce the power of the charging station to 5kW, for example, and charge more slowly. This avoids creating a peak in consumption on the network and reduces your electricity bill following the increase in low-voltage grid tariffs that came into force on 1 January 2025.

Prioritising charge points

This function allows you to prioritise one or more charge points. For example, I have a maximum power available for the charging infrastructure of 52 kW and there are 7 charging stations. I want one charging station to remain at 22 kW all the time – prioritising this station – and the rest of the power is distributed equally between the remaining 6 charging stations, i.e. 5kW each. Not all Load Management systems offer this functionality. However, it is available in both static and dynamic versions.

Scheduled charging

Some load or energy management systems can activate deferred charging sessions. This makes it possible to optimise energy consumption according to the power available at specific times (off-peak hours versus peak hours).

Smart charging management

Charging management, better known as Load Management or Smart Charging, is an intelligent system that enables a defined amount of power to be shared between several charging stations via wired or wireless communication.

Wired communication: the charging stations communicate with each other via a network cable (Ethernet cable with RJ45 connectors). Each charging station is connected in a star configuration to a common (unmanaged) switch. In this configuration, the most common communication protocol is Modbus TCP/IP. There are also charging stations which communicate with each other in series (bridging from one charging station to another with a 2-wire RS485 cable); in this case, the most common communication protocol is Modbus RTU. In both cases, we are talking about locally managed Load Management.

Wireless communication (OCPP Smart Charging): the charging stations are all connected to the Internet, either via Wi-Fi or GPRS (SIM card). The charging stations are then integrated into a load management platform, and load management is carried out remotely via this platform. The platform sends charging instructions directly to the charging stations via the OCPP Smart Charging communication protocol. This system requires stable Internet communication.

Smart charging management for AC and DC charging stations

This is a smart charging or energy management system that can manage both AC and DC charging stations in the same electrical circuit.

Smart charging station

A smart charging station is a charging station that:

a) collects, records and transmits data relating to charging sessions, including a unique identifier, the start and end date and time of each charging session, the amount of energy consumed, and the charging power;

b) can receive and execute remote commands to start, pause and stop a charging session, as well as perform smart charging management;

c) is equipped with a communication module that enables data exchange with a central system via a secure and interoperable communication protocol.

Standardised communication protocols

These interfaces enable standardised communication between different energy devices (charging stations, smart meters, photovoltaic panel inverters, heat pumps, storage batteries, etc.). Here are a few standardised communication protocols:

LAN (Modbus TCP/IP)
RS485 (Modbus RTU)
OCPP Smart charging (Cloud)
EEBus.

Static load management

Static: this involves distributing a given amount of power equitably between each charging station in the same cluster. For example, I have 40kW of power and 4 charging stations. If two cars are charging simultaneously, the two charging stations can each deliver 20kW. If 4 cars are charging simultaneously, each charging station delivers 10kW. This type of system is often programmable on the charging stations themselves and requires no additional external controller. There is a MASTER charging station in which the maximum power available is programmed, and the other charging stations are SLAVES, which receive instructions from the MASTER charging station. In this case, we are talking about a system that is specific to the manufacturer and integrated into the charging station technology. However, some brands of charging stations require an external controller (additional module) which will itself control a certain number of charging stations.

V2X bidirectional charging station

A bidirectional charging station is a charging station that enables bidirectional charging, either in alternating current (AC) or direct current (DC).

For the purposes of Klimabonus subsidies, a bidirectional charging station is defined as a charging station that supports the ILNAS EN ISO 15118-20 communication protocol.

Financial support for bidirectional charging stations will end on 31 December 2026, as from 1 January 2027, all AC charging points (public and private) must comply with ISO 15118-20:2022, in accordance with the amendment to the AFIR Regulation (EU) of 18 June 2025.

V2X bidirectional charging station “ready”

A “V2X-ready” bidirectional charging station means that the manufacturer has already incorporated the necessary hardware, but that the charging station still requires a software update to enable bidirectional charging in the future, once the regulatory framework and technical conditions allow it.

V2X-ready bidirectional charging stations supporting the ISO 15118-20 communication protocol are eligible for the Klimabonus 153 subsidy.

V2X communication protocols

The communication protocols required for the optimal operation of bidirectional charging are:

Between the bidirectional charging station and the vehicle: ISO 15118-20:2022
Between the charging station and a management platform (backend) or an Energy Management System (EMS): OCPP 2.1

ISO 15118-20:2022 and OCPP 2.1 are open communication protocols designed to ensure interoperability between charging stations and management platforms. This enables any compliant charging station to be integrated into any compatible management platform and vice versa.

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