From uncontrolled to bidirectional: analysing charging strategies for electric vehicles

The electrification of transport is a cornerstone of Germany’s energy transition, with electric vehicles (EVs) offering both decarbonization benefits and challenges for distribution grids. From 2025, § 41a of the Energy Industry Act (EnWG) will mandate that suppliers provide dynamic tariffs indexed to wholesale prices, complementing § 14a EnWG on load-dependent network charges. These regulatory measures aim to incentivize demand flexibility, yet their economic impacts on household EV charging remain unquantified. This study evaluates four charging strategies (uncontrolled, market-driven, smart, and bidirectional) from a household perspective. Using a mixed-integer linear optimization framework and using dynamic electricity prices, time-variable grid fees, and mobility profiles. Results show that uncontrolled charging under fixed tariffs produces the highest costs, while smart charging significantly reduces expenses and bidirectional enables negative net electricity costs under favourable conditions. Seasonal differences further highlight that winter price volatility increases both savings potential and exposure to cost variability. Overall, the findings suggest that dynamic tariffs and grid fees can enhance the economic case for smart and bidirectional charging, but their effectiveness depends on consumer acceptance and infrastructure availability.