Due to the declining prices and the government subsidies, photovoltaic systems are becoming more and more attractive. Nearly every photovoltaic system is connected to the public electrical network and therefore, this master thesis deals with the taxation of network-connected photovoltaic systems. Firstly, the author gives a short overview of the photovoltaic technology and reviews different system types before presenting possible subsidies for installation of photovoltaic systems. Further, this thesis shows the aspects of income tax and value added tax related to photovoltaic systems in existing companies. Additionally, the author deals with the taxation of photovoltaic systems in agriculture and forestry. Depending on the total quantity of generated electricity and the electricity consumption (for private purposes and for purposes of the agriculture and forestry business), a photovoltaic system can be assigned to the agricultural and forestry business or to the private area, or even can constitute an agricultural and forestry subsidiary or an independent business. Additionally, the author also puts emphasis on the taxation of photovoltaic systems installed on or adjacent to privately used houses. The operation of a photovoltaic system on or adjacent to a privately used house with regularly electricity feed into the public network can constitute an economic activity in regard to income tax and value added tax. In this case, the ratio of the total electricity generated by a photovoltaic system to the total private electricity consumption should be crucial, but this opinion is untenable due to the current decision of the European Court of Justice. According to the European Court of Justice it is only relevant, that electricity is supplied to the network in exchange for income on a continuing basis.