This paper presents a performance analysis of four types of air heating flat plate solar collectors: a finned collector with an angle of 75 degrees, a finned collector with an angle of 70 degrees, a collector with tubes, and a base collector. In this study, the first and second laws of efficiencies were determined for the collectors and comparisons were made among them. The results showed that the efficiency depends on the solar radiation and the construction of the solar air collectors. The temperature rise varied almost linearly with the incident radiation. The first law of efficiency changed between 26% and 80% for collector-I, between 26% and 42% for collector-II, between 70% and 60% for collector-III, and between 26% and 64% for collector-IV. The values of second law efficiency varied from 0.27 to 0.64 for all collectors? The highest collector efficiency and air temperature rise were achieved by the finned collector with angle of 75 degrees, whereas the lowest values were obtained for the base collector. The effectiveness order of the collectors was determined as the finned collector with angle of 75 degrees, the finned collector with angle of 70 degrees, the collector with tubes, and the base collector. (C) 2006 Elsevier Ltd. All rights reserved.