The electricity generation of these power plants induces costs due to reinforcements of the distribution grid mainly caused by an inadmissible increase of the supply voltage. The additional transmission and distribution grid costs which depend on the installed capacities of wind and photovoltaic power plants are based on costs values derived by studies determining the required grid reinforcements due to increasing contributions of renewable energies to electricity supply (EC, 2011, Dena, 2010a, BDEW, 2011). The first section gives a more detailed description of the scenarios considered as well as of the cost assumptions.