Nowadays, there is a growing interest in using of renewable energy sources, especially solar energy which can be converted into electricity by photovoltaic panels. In addition to traditional stand-alone photovoltaic systems, more and more new or modernized buildings are equipped with integrated photovoltaic systems (BIPV). The main aim of this paper is to compare two models used to calculate amount of electric power generated by photovoltaic panel. Analysed models were implemented into well-known simulation programs, ESP-r and TRNSYS
