Austrian solar prize for bidirectional charging stations for e-cars

There are over 5 million cars in Austria. If all of them were equipped with a battery of 40 kWh (kilowatt hours), this would result in a total storage capacity of 200 GWh (gigawatt hours) - that is more than the national electricity consumption of an entire day. As part of the 'Car2Flex' research project, an Austria-wide pilot application for the bidirectional operation of electric vehicles in conjunction with car sharing was implemented. At these first bidirectional charging stations, e-cars can not only charge electricity but also feed it back into the grid when needed. The project partners of 'Car2Flex' received the "Austrian Solar Prize" for this on October 5, 2024.

We congratulate all partners of the 'Car2Flex' project on this well-deserved award. Bidirectional charging allows electric cars to be used as buffer storage. This can enable the further expansion of renewable energy production, support the integration of electromobility into the energy system and stabilize the power grid at the same time, explains Andrea Edelmann, Chairwoman of the Green Energy Lab research initiative.

Bidirectional charging - how "Car2Flex" works

In the "Car2Flex" project, the capacities of the traction batteries of electric cars are used intelligently. Thanks to the innovative charging station, e-vehicles can be both charged and discharged to serve as buffer storage for households with PV systems or even to relieve the power grid. This means that electric cars can be charged with surplus electricity from photovoltaics (PV) during the day and feed electricity back into the grid in the evening. Users can use the Car2Flex app to define the extent to which their battery is available as a grid-supporting power storage unit. For fleets and car-sharing vehicles, this can be defined by the operator.

Vehicles as mobile buffer storage

During the day, the electric cars are charged using the in-house photovoltaic system on the roof of the residential buildings. Depending on the booking situation, the vehicle battery is also available as "mobile storage" for the power supply of the residential complex, for example for lighting the stairwell or operating the lift system. An intelligent control system ensures that at least 40 percent of the battery charge is always available for spontaneous trips, and there are also financial incentives for early vehicle bookings to improve planning: up to six hours before the planned start of the trip, use costs just EUR 7.50 per hour (instead of EUR 9.90). This simplifies the energy management of the vehicle battery and shows how user behavior can be positively influenced by incentive systems.

Electric cars could store up to 200 GWh of electricity

By charging electricity when there is an energy surplus and feeding it back into the grid when there is an increased demand for electricity, the vehicles can significantly reduce the overall load on the system.

In this way, they also support the further expansion of renewable energy production, such as solar and wind power, which are very volatile due to changing conditions. These fluctuations in power generation could be balanced out by the widespread use of bidirectional charging and the use of traction batteries as buffer storage. This would also benefit all electricity customers, as it would reduce the costs of stabilizing grid interventions. In 2023 alone, these cost electricity customers 141.6 million euros.

Short-term power shortages can thus be bridged

Sometimes we have too little electricity generation throughout the day to cover momentary peaks in consumption. This results in short-term bottlenecks on the consumer side. In future, we will be able to use the electricity from the vehicle batteries to compensate for the lack of electricity in the grid and will not need to commission large fossil fuel power plants, says Georg Lettner, project manager of Car2Flex.

The 'Car2Flex' project is being carried out as part of the Green Energy Lab research initiative and is funded by the Climate and Energy Fund as part of the "Vorzeigeregion Energie" program. Project partners include the technology companies Schrack and Fronius as well as the energy supply companies EVN, Burgenland Energie and Energie Steiermark.

Austrian Solar Prize for bidirectional charging stations for e-cars

Bidirectional charging - how "Car2Flex" works

Vehicles as mobile buffer storage

Electric cars could store up to 200 GWh of electricity

Short-term power shortages can thus be bridged

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Bidirectional charging - how "Car2Flex" works

Vehicles as mobile buffer storage

Electric cars could store up to 200 GWh of electricity

Short-term power shortages can thus be bridged

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