This paper presents the results of the conducted analysis on the on-grid photovoltaic installations designed for a single-family house by applying three different technologies (monocrystalline, polycrystalline and thin-film modules), compared to a simulation of the off-grid polycrystalline technology. As a result of the analysis conducted, the differences between the on-grid and off-grid systems could be determined. The simulation was made on the basis of the PV SOL program which allowed performing calculations concerning monthly and yearly yields during the period of 25 years, taking into account the average degradation of efficiency at 0.8% monthly. Additinoally, a return rate on investment was determined for different types of the analysed installations, taking into account an increase of electricity prices at 2.5% annually and a fixed subscriber’s fee (assumed as 38 euro monthly). Energy density (amount of energy acquired from 1m2 of the installation) and the amount of energy necessary to be purchased additionally from the electricity supplier to fully cover the demand for electricity for the analysed building were analysed as well.