Influence of Selected Weather Conditions on the Photovoltaic System Efficiency in Central Poland – Case Study

The article details the data obtained from monitoring the photovoltaic (PV) system in 2021–2023, equipped with a module for measuring basic weather parameters. The PV system under consideration, with a peak output of 3.2 kW p , is connected to the electricity grid and is mounted on the flat roof of the building. The annual relative yields of the generated energy were about 10% less than estimated, and their monthly distributions were asymmetric. In the “sum - mer” months (i.e., from April to September), the PV system generated, on average, about 75% of the whole year’s energy. The histograms of the PV system’s active power output showed that, on average, about 40% of the time, the PV inverter operated in underloaded mode. For selected weather conditions measured on site, a regression analysis was conducted with the active output power of the PV system. The main objective of the work was to develop a com - prehensive method for analysing PV plant monitoring data and the impact of weather conditions on its performance. The proposed method was realized as a case study for central Poland but can be implemented anywhere.