Experimental evaluation of the influence of infiltration on the efficiency of solar flat plate collectors

PBE (Brazilian Labeling Program) is a national program in Brazil that aims to establish standard criteria to compare the energetic efficiency and quality of several devices, such as refrigerators, vehicles, and flat plate solar collectors. The vast majority of solar collectors tested by PBE fail in the topic of infiltration of water condensation. Arguably, the presence of water inside the collector decreases its efficiency, since part of the solar radiation is lost to heat the infiltrated water. However, the determination of the heat losses due to infiltration has not yet been proven in actual flat plate solar collectors, since it has not yet been properly measured. The aim of this study was to evaluate the influence of water infiltration in the efficiency of flat plate solar collectors, evaluating devices from three classes of energetic efficiency: A, B, and C. For the samples evaluated, it was observed that the influence of the amount of water infiltrated on the efficiency is not significant. Therefore, this criterion should not be used to promote the rejection of the collector.