In the field of renewable energy sources photovoltaic systems, especially thin-film modules, are one of the most promising technologies. This resulted in a rise of the demand and consequently in a time-delayed growth of the amount of used modules, which need an appropriate recycling process. An adequate processing is supposed to separate the actual modules (active layers and contacting including both glass substrates) from the other components (frame, wiring, etc.). The former subsequently end up in a hydrometallurgical process. In this the precipitation is one possibility for a recovery step to separate the metals of the CIGS layer dissolved by leaching with sulfuric acid from the solution. In order to design the experiments, an enquiry on the configuration of the thin-film modules, already existing recycling technologies and certain basics of the inorganic chemistry is required. The aim of this master thesis is to determine the applicability of the precipitation with preceding leaching with sulfuric acid for the retrieval of valuable metals, which uses zinc oxide as precipitant. The testing of this reagent is performed in various dosing amounts and separation steps.