The performance of a 15 kWp roof mounted, low angle tilted photovoltaic installation over the year 2019 has been analyzed in terms of the role of solar irradiation, ambient and module temperature, clouds cover and wind speed. The studied photovoltaic system operates under warm summer humid continental climate with the considerable influence of temperate oceanic zone. The role of significant changes of weather conditions in warm and cold part of the year has been shown. The negative impact of external temperature increase on the modules efficiency has been observed. The experimentally determined temperature coefficient of efficiency of the modules is equal to -0.06%/°C. Relatively high sum of insolation registered in the location in 2019 together with a lack of shade assure annual energy yield of 1098 kWh/kWp, energy density 188 kWh/m2, capacity factor 12.53% and performance ratio 82%.