The expansion of renewable energy production and the increasing number of controllable large-scale consumers - especially electric vehicles and heat pumps - pose growing challenges for the distribution grid. At the same time, they are forcing a paradigm shift from a demand-oriented to a supply-oriented electricity market, so energy consumption is shifted to times when more renewable energy is available. Dynamic electricity tariffs can motivate customers to shift their energy consumption to periods when electricity is cheap, and renewables are abundant. However, this approach only considers the market perspective and does not motivate grid-friendly behaviour. To keep the grid stable, §9 EGG allow curtailing renewable power production, while §14a EnWG lets grid operators control flexible consumers like EVs or heat pumps. With reduced grid fees for controllable loads (Module 2), customers are incentivized to allow grid operators to throttle down their power consumption to 4.2kW. Additionally, variable grid fees (Module 3) aim to encourage load shifting based on grid conditions through price signals.

Bidirectional charging offers new revenue potential, which depends not only on market prices but also on taxes, levies, surcharges, and grid fees. This paper analyzes the Vehicle-to-Grid economic potential from the customer perspective, focusing on §14a EnWG Modules 1–3 and the effects of a hypothetical full grid fee exemption in the context of a potential Module 4. The analysis also focuses on how a new metering concept for temporarily stored grid electricity in bidirectional electric vehicles affects the potential benefits across different use cases. Unlike stationary batteries, it's difficult to accurately measure charging and discharging losses for electric vehicles. Therefore, this paper suggests using a fixed, average AC efficiency loss of 20% for exemption from surcharges, and analyses how this assumption affects the profitability of V2G operations. Additionally, photovoltaic electricity that is temporarily stored in the electric vehicle and later fed back into the grid can currently be interpreted as traded energy, which can lead to unintended refunds of taxes, grid fess, levies, and surcharges. To prevent such incorrect incentives, this paper introduces a "Trading Budget" approach and evaluates its impact on this effect.

The analysis is based on EBZ OptiTwin, a rolling mixed-integer optimization model designed to simulate energy flows in residential households. For this study it has been extended with a new metering concept developed in the project "BDL Next" for bidirectional electric vehicles. For the first time, this allows accurate measurement and separation of energy fed back into the grid, clearly distinguishing between different market categories such as trading conventional "grey" electricity or renewable "green" electricity with EEG remuneration.

Our study shows that dynamic grid fees can increase annual customer benefits from bidirectional electric vehicles (V2G) by up to €300. Much of the benefit can already be reached with unidirectional charging, so it’s not mainly due to bidirectional use. In contrast, the full grid fee exemption brings high savings only with bidirectional charging. There’s no real benefit for unidirectional charging in this case. Additionally, recognizing a fixed 20% efficiency loss makes regulatory treatment fairer compared to stationary batteries and can further increase V2G profits by up to €100 per year.