Integrating Electric Vehicles into the German Electricity Grid - an Interdisciplinary Analysis

This study analyses the integration of electric vehicles (EV) into the German power grid including different demand side management (DSM) approaches from a technical, economical and user perspective. For this an overview of the future German electricity market with the focus on EV integration is given. It is shown that for conservative EV penetration rates the effect on the electricity generation is marginal while the shortage in the regional and local electricity grid could be already significant. DSM in combination with smart grids can help to tackle this issue by controlled charging of EVs. One simple concept is to postpone the charging process by offering incentives to vehicle users e. g. with dynamic electricity tariffs. The common Time-of-Use (TOU) tariff defines in advance a dynamic tariff scheme according to the load forecast for the following days. This allows to release the local electricity grid and to increase the share of renewable energies: In times of high electricity generation by renewable energies and low electricity demand the price is low and vice versa. The impact of these dynamic tariffs on the charging process of EVs is shown in a techno-economic analysis for an exemplary urban high voltage grid by an optimising energy model. These strong impacts are however somewhat reduced by the acceptance and the low profits for the single user. At least for the users in a German field trial, environmental aspects played a major role in influencing the charging behaviour – this gives still hope for the future.