This paper analyses the photovoltaic parameters of the most promising CdS/CdTe solar cells for large application prepared by close space sublimation (CSS) and high vacuum evaporation (HVE). CdS/CdTe solar cells that have an efficiency of~10 % have been studied by current-voltage, capacitance-voltage and quantum efficiency measurements. The current-voltage characteristics show that the addition of small amounts of Cu or Te to back contacts by thermal evaporation improves contact properties by p+-doping the CdTe surface and creating a pseudo-ohmic contact. The cell deposited by CSS seriously suffers in FF compared to the cells prepared by HVE. For both types of the cells above mentioned measurements reveal that the efficiency of CdS/CdTe solar cells fabricated by CSS is limited by a light-dependent shunt resistance and by a high series resistance, but concerning of the cells fabricated by HVE - by the formation of a thick layer of CdS1-xTex at the interface.