In this study, the performance of three kinds of solar collectors was analyzed according to operating conditions through theoretical method. The flat plate, U-tube, and heat pipe solar collector was used to compare the performance with operating condition.. As a result, the maximum efficiency of flat plate, U-tube, and Heat pipe solar collector was 61.3%, 59.7%, and 69.2%, respectively, when the water was used as the working fluid in the solar collector. The highest efficiency of heat pipe was 7.9% and 10.8% higher than that of flat plate and the U-tube solar collector. When the Al2O3 nanofluid was applied in the solar collector, the maximum efficiency of flat-plate, U-tube, heat pipe solar collector was increased by 17.9%, 16.9% and 11.3%, respectively, compared to that when the water was used.