Before revision:   In this paper we analyze the current situation of wind and photovoltaic (PV ) power in-feed in the German electric power system and their effect on the spot market \approx20 .
After revision:  tear and start-stop constraints. In this paper we analyze the current situation of wind and photovoltaic (PV ) power in-feed in the German electric power system and their effect on the spot market \approx20 .