How EVs in Germany are balancing the power grid

Electric cars in Germany now help stabilize the national power grid

Pilot Project "OctoFlexBW" Demonstrates How Private EVs Can Support Grid Stability

In the pilot project OctoFlexBW, transmission system operator TransnetBW and energy supplier Octopus Energy successfully harnessed flexibility from private electric vehicles to support redispatch operations. The focus was on establishing a seamless, energy-market-compliant process chain—from sending the necessary signals to controlling consumption units in households—as well as on metering and billing.

The project bundled over 700 battery-electric vehicles from private households and integrated them into the redispatch process. This was made possible by linking TransnetBW's DA/RE platform (short for Data Exchange/Redispatch) with Octopus Energy's KrakenFlex flexibility platform. Using this system, the transmission operator could generate demand signals when grid congestion was forecasted and transmit them via standardized interfaces to the aggregator. There, the signals were converted into specific control commands for connected charging points, allowing charging processes to be temporarily shifted or reduced to ease grid strain.

A key finding of the project is that this form of flexibility provision can be fully integrated into existing redispatch processes. According to the partners, all necessary process steps—including the transmission of planning data on flexibility availability, standardized communication along established Redispatch 2.0 procedures, and energy-market-compliant settlement of actual load adjustments—were successfully implemented, tested, and automated.

The project also provides robust data on available flexibility volumes. With a fleet of around 700 vehicles, a daily flexibility capacity of approximately two megawatt-hours was achieved. Scaled up to a much larger fleet, the potential becomes substantial: one million electric vehicles could provide several gigawatt-hours of flexibility per day, covering a significant portion of Germany's current redispatch needs.

For users, the system is straightforward—they simply set a desired charging level by a specific time (for example, a full charge by 8 a.m.). Within these parameters, the aggregator optimizes charging based on electricity prices and grid conditions. The project partners report no noticeable loss of convenience for participants, who also benefited from lower electricity rates. This combination of economic incentives and minimal disruption is seen as crucial for broad acceptance and scalability.

Building on these results, the partners advocate for further development of redispatch regulations, which currently rely on a cost-based mechanism compensating power plant operators for adjustments. Looking ahead, a market-based supplement—dubbed "Redispatch 3.0"—could unlock decentralized flexibility. In such a model, aggregators would actively offer flexibility, with price signals determining deployment. However, this would require appropriate regulatory frameworks, particularly for cost recognition by grid operators, as well as accelerated digitalization of grid infrastructure, such as the rollout of smart metering systems.

The project also fits into a broader energy transition context. As electrification expands in transport and heating, the potential for controllable loads in low-voltage grids grows significantly. Beyond electric vehicles, heat pumps, home storage systems, and other flexible consumers could contribute to managing grid congestion. Their integration could not only reduce redispatch costs but also decrease reliance on fossil-fuel power plants, which are currently often used to stabilize the system.

With the OctoFlexBW project now complete, the partners are already planning their next moves. In the follow-up initiative, DataFleX, additional vehicles and further technologies—such as home energy storage systems—will be integrated, while processes will be scaled up even more. The team is also assessing how the model could be adapted to other grid levels, additional control areas, or even European platforms.