KOSTAL Pressebereich
Hagen, 13/07/2021

The new bidirectional charging station from KOSTAL turns electric vehicles into controllable energy storage units

KOSTAL's new and revolutionary bidirectional BDL wallbox charging station for electric vehicles is now being put to the test by private customers and commercial operators.

KOSTAL's partner, BMW, handed over the first 20 BMW i3s, designed to work with charging and discharging technology, to private users for testing under real-life conditions on 9 July 2021. Over the next few weeks, 30 more cars of this model version will be added to corporate fleets. Here too, they will be able to prove their performance, sustainability and efficiency as they have been designed to make electromobility even more comfortable and cost-effective with fewer emissions.

This test run stems from the three-year joint research project "Bidirectional Charging Management - BDL", which has been supported by the Federal Ministry for Economic Affairs and Energy since 2019 under the auspices of the German Aerospace Center, in which KOSTAL developed the bidirectional charging station, the key component for charging and discharging the vehicle. The station ensures optimum and highly efficient interaction between the inverter of a photovoltaic system, or other connected energy sources, and the electric vehicle during charging and discharging processes as well as control options for an energy supplier.

For KOSTAL, as a long-standing automotive electrics and solar power expert, and for partners from the automotive industry, the charging infrastructure sector, the energy industry and research, the fundamental approach of the project is as all-encompassing as it is super-intelligent and ground-breaking. For the first time ever, vehicles, charging infrastructure and power networks are to be connected in such a way that 100% renewable energy and supply security increase at the same time. The transition to sustainable energy sources is increasing the number of electric vehicles, bringing with it not only a greater demand for electricity but also the need for intelligently control of electricity capacities. Because only with perfect regulation can optimum use be made of renewable energy sources, enabling us to sustainably increase quality of life.

While the task force at KOSTAL Industrie Elektrik GmbH is adding the bidirectional wallbox to the new system as an innovative conversion and control centre, the project consortium consists of the BMW Group, the provider of the electric vehicle, TenneT and Bayernwerk Netz GmbH, the energy system service providers responsible for transmission and distribution, and the scientific laboratories of energy research institutes Forschungsstelle für Energiewirtschaft e.V. (FfE) and Forschungsgesellschaft für Energiewirtschaft mbH, the Karlsruhe Institute of Technology and the University of Passau. Their work provides information about the energy system analysis, repercussions for the electricity market and grid, and user behaviour.

Two-way energy flows for more efficiency and flexibility

Bidirectional charging enables exceptional flexibility in the use of renewable electricity. With a conventional setup, electricity flows from the grid, another energy source (e.g. a wind turbine or combined heat and power plant) or a photovoltaic system, potentially with storage connected, via the charging station into the electric vehicle. This is how customers drive cost-effectively with environmentally sound electricity. - With the bidirectional wallbox and a discharge-compatible electric vehicle, it is also possible to feed the electricity available in the car battery back into the home's own consumption or into the grid. This increases the flexibility to make electricity available in a way that serves the grid or is relevant to end consumption, while also cutting costs. Since during the charging process every electric vehicle is a consumer in terms of the network, the grid and also in-home energy sources and their controlling components must be adapted to this consumer situation of the electric vehicle as mobile energy storage. As a system supplier, KOSTAL already offers all components related to charging with highly efficient performance and easy handling from a single source.

Perfect load management as an optimisation solution for feeding electricity back into the grid or for self-consumption.

Bidirectional charging opens up the possibility of adapting energy storage and feeding back electricity from the car battery to consumption cycles and grid restrictions from a profitability standpoint in order to achieve greater efficiency.

With a device-integrated energy management system in the wallbox, optimum charging and feed-in points can be managed so as to absorb peak loads. This flexibility is increased massively with a bidirectional wallbox. The best charging or discharging time can be determined from parameters including the future range required for the vehicle, the electricity tariff level at the planned charging time, the household’s electricity demand and the amount of self-produced (solar) electricity. So the charging time becomes something that can be calculated and optimised, is freely selectable and uses cars with short and long immobilisation times to balance the grid level.

With bidirectionality, the electric vehicle becomes a useful energy source in four different ways. Firstly, it lends itself to feeding into the grid (vehicle-to-grid) in order to participate in new energy trading models and contribute to grid stability. Secondly, in a fleet network, an electric vehicle takes on the role of a storage power plant for short-term use. Thirdly, when power is returned from the car battery to the home, increased home demand is covered by environmentally sound electricity (vehicle-to-home), and lastly, as a power bank it functions as a charging station for connected electrical devices such as smartphones or laptops (vehicle-to-load). What’s more, it can also take on the role of a mobile charging station to charge other electric vehicles (vehicle-to-vehicle).

The higher load on the vehicle battery for this application is not seen as an issue by the industry in that protection standards are met. Scientific analyses have found that the main criterion for battery replacement is the age of the storage unit, not the number of charge cycles.

More self-sufficiency for the home through the use of bidirectional wallboxes

With the help of the bidirectional wallbox from KOSTAL, it is possible to temporarily store self-generated energy (e.g. from a solar system) in an electric vehicle. This can then be fed back to cover the household's electricity requirements as needed. If the daily demand of a home is 11 kW per day, for example, a 55 kW electric vehicle can return its charge to the household during planned immobilisation times and thereby cover the household's energy demand for days on its own. This cuts electricity purchase costs and use is made of the cheap solar power that was previously used to charge the vehicle instead of more costly line current. And at the same time, CO2 emissions are reduced considerably. - A profitable venture in every respect.

With bidirectional charging via the electric vehicle, not only can private home users enjoy increased self-consumption, but emergency power capacities also become available – when all the specifications of the grid operator are taken into account – and with tariff-optimised processes, charge cycles can deliver greater profitability.

The commercial vehicle fleet is parked up... and at the same time offers high electricity efficiency

With bidirectional charging stations, companies will in the future be able to charge their vehicle fleet at times of lower load levels and discharge the vehicles connected to the bidirectional wallbox in the network during the highest load peaks. This cuts peak loads and at the same time supplies the in-house operation with environmentally sound and cost-effective electricity. Optimised fleet charging also allows expensive grid electricity purchases to be reduced because, if necessary, vehicles from the fleet can feed electricity back in order to charge higher-priority vehicles without exceeding the maximum amount of drawn power.

The BDL wallbox from KOSTAL – the unique future-oriented charging station

The formula of the BDL wallbox is brilliant: powerful, compact, lightweight, intelligent. – With its BDL wallbox, KOSTAL is establishing a charging station that elegantly combines a tried and tested approach with a revolutionary new one. The housing concept is similar to that of the proven highly efficient all-round inverter PLENTICORE plus. Already a brilliant product in itself, it features clean lines, robust weather-resistant design and compact construction and its housing qualities now add a touch of class to the BDL wallbox. At just over 20 kg, the BDL wallbox is a lightweight that can be installed quickly and easily by just one specialist. Charging and discharging takes place at a powerful 11 kW and a feed-in mode complying with the VDE AR N 4105 standard is guaranteed. In discharge mode, a maximum of 10.5 kW can be fed back into the grid. The BDL wallbox has a DC output in the voltage range of between 250 and a maximum of 475 volts with a DC current of up to 33 amps. Its large dimensions ensure fast charging cycles and high availability.

The operating principle of the BDL wallbox is simple and perfect at the same time: it charges the electric vehicle using adjoining energy sources such as a PV system or other energy sources connected to the solar system’s inverter. When operating in reverse, feed-back via the BDL wallbox is possible and the device establishes a connection between the AC grid, vehicle, building and backend.

The bidirectional charging station is equipped with all the future-oriented communication interfaces that are associated with highly flexible and hugely efficient continuous operation. Via PLC, Ethernet, GSM, RS485 and RFID, all network connections and authentication requirements can be optimally managed. The operator backend is operated via OCPP. Software updates are easy to perform via the LTE connection. This ensures that the wallbox is always up-to-date and has the latest function modes.

Particular attention is paid to the other interface protocols Modbus and EEBUS as these are used to collect the relevant parameters for increasing efficiency and to allow them to be exchanged between households and energy suppliers. Operating in real time, the energy management system continuously optimises the generation and use of electricity, lowering costs while maximising benefits. In conjunction with a smart energy meter (KOSTAL Smart Energy Meter), all energy flows in the home are measured and are available as data for analysing and modifying the system.

The charging station can be connected to the electric vehicle using the internationally standard CCS Combo plug. This plug allows charging in direct current mode, making possible a wide range of applications for a whole host of different vehicle types.

Energy flexibility for electric vehicles attains a new dimension with the bidirectional BDL wallbox from KOSTAL. For more sustainability. For greater benefits and the greatest possible efficiency. Simply making smart connections.

KOSTAL Industrie Elektrik GmbH

KOSTAL is an independent family-owned company founded in 1912. With 20,000 employees worldwide, it develops, manufactures and distributes automotive and industrial applications. KOSTAL generated around €2.6 billion in turnover in 2020.

In addition to automotive electrics, the KOSTAL Industrie Elektrik division has a history spanning more than 20 years, specialising in the development and production of grid-connected power electronics, such as PV inverters, which communicate via networks. As a system supplier for the entire AC and DC portfolio up to 22 kW, including bidirectional DC charging, KOSTAL provides all energy system components from a single source. The extensive, diverse portfolio also includes individual advice, the development of special customer solutions for applications far removed from off-the-shelf products and a comprehensive service package. Customers benefit in particular from KOSTAL's detailed knowledge of the overall system and the interaction between on-board charging, off-board charging and photovoltaics in the electromobility and solar power sectors. KOSTAL's philosophy is to realise the greatest possible interoperability between PV system, wallbox and electric vehicle in an optimum and highly efficient way.