Assessment of the influence of environmental factors on the energy yield of a PV/T plant

Photovoltaic/thermal (PV/T) collectors can deliver electricity and useful heat from the same surface, but their output is strongly shaped by outdoor conditions, so their electrical and thermal outputs are driven by several weather factors acting at the same time. In this paper, we analyse a rooftop PV/T system operating in Mediterranean summer conditions using a set of complementary tools, Pearson and Spearman correlations, pair plots, time-based maps, wind rose and polar plots, and a daily-peak analysis where wind vectors are overlaid on irradiance and temperature conditions. The results show that solar irradiance is the main driver of both electrical and thermal power, with correlation values of 0.99 and 0.95, respectively. Ambient temperature mainly increases together with irradiance during the day, but it still causes electrical losses; electrical power typically drops by about 5 to 10 W when ambient temperature rises from 300 to 315 K. Wind speed has a secondary stabilising role, while wind direction alone shows a weak linear link in this dataset, mainly because most recorded winds are below 4 m/s. Over the monitoring period, the system produced more than 1.1 MWh of heat, about 4.5 times the electrical yield. These findings underline the value of analysing climate effects in a coupled way and provide a basis for wind-aware modelling and control of PV/T systems in real operating conditions.