In recent years, photovoltaics (PVs) is the main driver of the renewable energy market growth in Poland. The number of photovoltaic installations, most of which are rooftop prosumer systems, is consistently growing. Therefore, the determination of the applicability and feasibility of photovoltaic systems under different climate conditions is of great significance. This study presents the performance analysis of four prosumer photovoltaic installations situated in the Eastern part of Poland, Lublin Voivodeship. The influence of various tilt angles, ranging from 19° to 40°, and azimuths (south, east, south–east, and east–west) on the final yield have been determined under one year of operation (2022). The average yearly final yield was found to be 1022 kWh·kW−1, with the highest value obtained for the installation oriented towards the south, equal 1079 kWh·kW−1. Then, the PV systems were simulated by the use of four specialized photovoltaic software: DDS-Cad 16, PVGIS 5.2, PVSOL premium 2022, and the PVWatts Calculator 8.2.1. A comparative analysis of the measured and simulated data in terms of the final yield was carried out. The data obtained from PVGIS and PVSOL demonstrated the highest degree of overall alignment of 92% and 91%, respectively. The most significant underestimation was noticed for the DDS-Cad software, which was equal to 77%. The most accurate predictions stand out for the system oriented to the south, while the weakest was found for the E–W installation.