The conference
is English

April 27-28, 2023
Aachen, Germany

Conference in the framework of the Battery Conference 2023


April 27-28, 2023 Aachen, Germany

Conference in the framework of the Battery Conference 2023

April 27-28, 2023
Aachen, Germany

Conference in the framework of the Battery Conference 2023

On the topic

Vehicle-to-Grid (V2G), Vehicle-to-Home (V2H), bidirectional charging, the car as electricity storage for grid stabilization (control energy), new grid services, CHAdeMO plug

It is becoming increasingly clear that more electrical storage facilities are needed for the energy transition. In particular, eliminating instantaneous reserve due to the increasing reduction of rotating masses in generators requires rapid alternatives. Furthermore, there is currently an enormous increase in storage due to the substantial increase in electric cars (battery vehicles). There, storages per electric car between 40KWh and 150 KWh are standard. What could be more evident than combining these two things? Economically, this makes sense and would save much money because, in this way, the grid expansion and grid reinforcement can be planned differently. Technically, the electric cars must not only be able to absorb energy (charging) but also feed it back into the grid for grid stabilization. One necessity for this is a communication infrastructure that applies to all. In addition, a higher-level management system must be set up to prioritize landing and discharging. With further growth in electromobility, however, intelligent charging will be mandatory because otherwise, the networks will be overloaded. Technically, bidirectional charging is already well advanced. What needs to be added are specifications and incentives from the legislator. In addition, it must be considered that only part of the existing electric cars is connected to the grid. Therefore, there must also be a monetary added value for the electric car owner if your battery is made available for grid stabilization.

There are many uses for the bidirectional charging of electric vehicles. In this context, an owner can gain an advantage through self-use as home storage. However, other possible uses by third parties require appropriate remuneration and guaranteed to charge states, which must be considered in the respective business model.

The Volkswagen Group has announced that all ID models will be able to charge bidirectionally in the future. An OTA update (version 3.0/3.1) is planned for 2022. Vehicles with the 77 kWh battery should be able to charge bidirectionally after the update.

FAQs | 10 questions to the organisers


Could you please give us a basic definition of Vehicle-to-Grid (V2G) and explain how this technology is changing the energy industry?

Vehicle-to-grid describes a system-serving discharge of electric vehicles. For example, the vehicles can deliver energy when there is a shortage of electricity, e.g. because not enough fluctuating renewable generators are producing electricity. Sometimes, however, the term vehicle-to-grid is also used in practice as a collective term for various concepts such as vehicle-to-home, vehicle-to-load and smart charging.


What are the key benefits of V2G for electricity grids and end consumers, especially in the context of renewable energies?

Vehicle-to-grid is particularly relevant when renewable electricity generation is not sufficient to cover the load. This can either be at short notice because, for example, clouds appear or there is an unplanned wind lull. In these cases, there is a need for quick flexibility in the power grid, which the e-cars can provide. But vehicle-to-grid can also play a role in periods of hours to a few days in order to transmit surplus electricity in times when not enough electricity is produced.

Smart charging is particularly interesting for the grids. Vehicles can be controlled in such a way that they reduce their consumption when the power grids are at their limits. Such bottlenecks can occur both in the distribution grid and in the transmission grid.


Which technologies and infrastructures are necessary to successfully implement and operate V2G systems?

Various actors have to work together to achieve this: Customers provide the vehicle, aggregators combine different vehicles and market them on the electricity market, energy suppliers can also help via dynamic electricity prices. The necessary technologies are bidirectional charging stations, bidirectional vehicles, (open) protocols such as ISO 15118-20 and OCPP 2.0, and intelligent IT systems from aggregators.


What advances have been made in V2G technology in recent years and how do these influence market penetration?

With ISO 15118-20 in April 2022, essential foundations were created, because before that only the CHAdeMO standard could charge bidirectionally. In addition, the battery capacity of vehicles is now sufficiently large that a buffer is available for vehicle-to-grid because the full capacity is no longer required for driving. Almost all OEMs, charging infrastructure manufacturers and integrators are currently working intensively on this topic.


How can V2G support the integration of electric vehicles into the overall efficiency of a building or city?

At the level of a building, for example, the grid connection capacity can be reduced because peak loads are served by vehicles or, in the case of smart charging, are at least significantly capped. At the urban level, the expansion of the distribution network can be delayed.


What business models and incentives already exist to encourage car drivers to participate in the V2G network?

There are various models on the market. Dynamic electricity tariffs are well known, where customers pay the intraday auction or day-ahead price for their electricity consumption, for example. More advanced business models optimise on different markets and integrate vehicles with other flexibility sources, such as storage or flexible loads. A number of players are currently active in this area, and you will also meet them at our conference.


What challenges and obstacles still stand in the way of the widespread introduction of V2G systems?

In Germany, the lack of smart meters is particularly important, as without them integration into the electricity markets is almost impossible. In addition, there is the challenge that currently high fees have to be paid for electricity purchased, which exceed possible income from electricity trading. This is referred to as double taxation.


Can you give some examples of successful V2G implementations in different regions or countries?

Previous approaches have often been in the form of projects, which we have already seen at our conference. Implementation in the sense of a commercial product is only just beginning, but we already have a good example here with Renault and Mobility House. Dynamic electricity tariffs, such as those offered by Octopus, Tibber and some others, also play an important role here.


How could governments and energy companies support V2G initiatives and drive the scaling of this technology?

In particular, governments should remove the current obstacles such as the lack of smart meters and double taxation. Beyond that, however, I advocate that the government should only create suitable framework conditions so that the best solutions can be found on the market. Energy companies, on the other hand, should focus on commercialisation so that the market can actually be activated and the corresponding potentials can be raised.


To what extent do you expect V2G to change the way we generate, store and distribute energy in the coming years, and what developments can be expected in the field of V2G technology in the near future?

Vehicle-to-grid and smart charging are a stroke of luck with regard to the energy transition, because potentially huge storage potentials are available here. I believe that, as in other markets, we will see a supply curve where some players can offer a lot of flexibility at low prices and others call for higher prices. Overall, this flexibility allows us to build large amounts of renewable generation.

For bidirectional charging to work, the following groups/companies must enter into agreements: electric car owners, electric car manufacturers, charging infrastructure manufacturers, service providers, electricity grid operators, legislators, and standardization bodies.

Depending on the application, different actors can benefit. In addition, the control unit must be connected to various data sources depending on the application.

Technical basics

To charge the battery from the mains, a rectifier is required to convert the alternating current into a direct current. Furthermore, when charging the battery, the current must be regulated using a charge controller so that the battery is not overcharged. If the car battery is to supply power to the grid, an inverter is required to convert the battery’s direct current into an alternating current. There are bidirectional inverters supporting both functions, i.e., rectifiers for charging and inverter for discharging to the grid.

Electric cars can be connected directly to a 230V household socket for charging. This was often done with the first vehicles when there were no wall boxes. The car is charged directly with an alternating current (AC). In AC charging, the rectifier is therefore built into the vehicle, and it depends on the vehicle manufacturer how the rectifier is dimensioned. The rectifier can charge at a maximum of 2.3 kW on a household outlet. Many electric cars can also be set at a three-phase socket. In this case, the charging power is higher, usually 10 kW, often 20 kW, or even up to 40 kW (63 A per three-phase current phase), and the rectifier in the car must be designed accordingly. When connected to a standard socket, charging is uncontrolled from the outside. Only the charge controller in the car decides whether and how much to charge.

If charging is also to be controlled from the outside, the vehicle must be connected to a charging station (wall box or charging column). This is often the case at higher power levels and public charging stations. The charging station can then tell the charge controller in the car how high the power should be. In AC charging, however, it is only a control unit and cannot change the power flow itself.

Plugs for AC charging in North America and Japan are mainly type 1 plugs. In Europe, the most common plug is type 2, also known as the Mennekes plug. Both plugs have two additional pins where information about the maximum charging power and the charging power to be set at the moment is transferred. However, it only allows data communication from the charging station to the vehicle, not back, and can also not be supplemented with further information.

In DC charging, the rectifier and charge controller are located in the charging station. This means the charging station contains power electronics and can adjust the power flow independently. However, this makes a DC charging station much more complex and expensive than an AC charging station.

Since the size and weight of the rectifier play a much smaller role than in the vehicle itself, it is possible to realize much larger charging capacities of over 100 kW. When and how much charging takes place can then be determined by the charging station.

If the battery in the vehicle is to be used for other purposes, such as bidirectional charging, the charge controller must know when and how much the battery will be charged and discharged. For this purpose, a data connection must be from a control unit to the charge controller. In addition, a control unit must also know how far the battery is currently charged and when the user plans to drive the vehicle and wants a charged battery. For this reason, a connection must exist from the car back to the control unit.

If a charging station is used, it may contain a control unit for bidirectional charging. However, with AC charging using the widely used type 2 plug, there is only an analog data connection from the control unit in the charging station to the charge controller, which, moreover, can only control the charging of the battery. For these reasons, bidirectional charging with AC charging is currently only very rarely available. On the other hand, with DC charging, the power electronics are in the charging station. Furthermore, a data connection to the vehicle could be dispensed with because the charge controller, which determines the direction of the current, is located in the charging station and can be connected to the control unit there. However, the protection electronics in the vehicle must know about the discharging, and the state of charge and end time should also be able to be transmitted from the car to the control unit. Therefore, a data connection in both directions is also necessary for practice for DC charging.

However, a sufficient data connection is only available with the CHAdeMO connector. The CAN bus protocol has been extended for discharging to the grid and allows a data connection from the vehicle to the charging station. In contrast, the CCS plug uses the same data communication as the Type 2 AC plug and is not readily suitable for bidirectional charging. In the future, the CCS system, in conjunction with ISO 15118, will also offer the possibility of regenerative charging.

Today, however, bidirectional charging is only possible with the CHAdeMO plug. There are already the first e-vehicles in Europe that can feed back into the grid.

One elegant way to bypass the tangle of connectors for data transmission is to use a wireless data connection via radio. The new V2X (Vehicle-to-Everything) standard can be used here. This is used for traffic networking and includes communication via radio between vehicles and between cars and infrastructure. The latter can also be used for data transmission between vehicles and charging stations. The first vehicles are already using V2X. Now, a company commercially offers a bidirectional charging station with a CCS connector and implements the necessary data transmission with V2X.

There are several standardization activities in the VDE that concern bidirectional charging. It states: “The DKE/AK 353.0.401 “Bidirectional charging” working group is responsible for aligning the standardization process in the best possible way and for adapting the results in the best possible way for standardization.

Many necessary standardization activities exist for the “bidirectional charging” field of action. For example, the IEC 61851-1 standard contains the basic communication principles for controlling charging processes in electric vehicles. In addition to standards, VDE application rules are decisive for connecting charging facilities such as charging stations or wall boxes.

The electric car’s battery can serve as a substitute for home storage, especially in conjunction with a photovoltaic system (vehicle-to-home, V2H). This is worthwhile if the vehicle is frequently connected to the charging station during the day. It can effectively serve to increase the self-consumption of the photovoltaic system. In the evening, after sunset, some energy in the battery can be used for household purposes. Given the sharp rise in electricity prices, this model is particularly attractive.

In principle, one could even imagine using the vehicle battery for emergency power in the event of a power outage. As with home storage, however, the inverter in the bidirectional charge controller would have to be capable of islanding. Car manufacturers are also working on offers for this.

If grid operators, electricity traders, or operators of virtual power plants want to use the electric car’s storage capacity, the owners’ benefit must become apparent. Business models must consider appropriate remuneration for the power. Likewise, vehicle owners must be guaranteed a minimum amount of energy and, if necessary, complete charging at a specified time. This must be taken into account in the respective business models.

Most applications can only be implemented if many such vehicle storage units are controlled together as swarm storage units. A correspondingly reliable data connection from a central control unit is therefore necessary in most cases.

It must be considered that not all vehicles in such a swarm are always connected to the power grid. Statistical probabilities must be used here. In particular, the use of vehicle fleets of operators can be interesting in this context since the times of use are much better known and predictable.

Electric cars can be used in large numbers in the future to regulate and stabilize the power grid. Since they will exist in large numbers in the future, this would be the most significant benefit to the power grid. So, the charge controllers could supplement the instantaneous reserve, which takes effect at the first moment of load fluctuations and stabilizes the grid frequency. Currently, this is still done by large rotating masses of generators in large power plants. In the future, this function will have to be performed by devices with power electronics.
An operator of a virtual power plant could form swarm storage with electric vehicles as an aggregator and sell the power on the balancing energy market.

Primary control, in particular, is attractive for use with batteries. The power called up is proportional to the deviation of the grid frequency from the setpoint. However, it rarely deviates seriously, so little, if any, power needs to be supplied most of the time. Furthermore, the market for primary control is so attractive that it is already possible to profit from batteries.