The efficiency of current flat plate solar thermal collectors is relatively low. This demonstrates unequivocally the necessity for more study in the field to increase those collectors’ efficiency through the use of various strategies. Thus, the purpose of this study is to assess how various factors, such as tube configuration, kind of working fluid, and flow rate, impact a flat plate solar collector’s thermal efficiency. A single spiral copper tube measuring 15 meters in length was utilized to examine the impact of the tube arrangement while maintaining similarity to the standard design in all other configurations. Five alternative fluid flow rates, means 1, 1.5, 2, 2.5, and 3 lit/m, were tested experimentally under all circumstances. In order to evaluate the effect of the fluid thermal properties on the efficiency of the collector, water, CuO, and Al2O3 nanofluids with two different nanoparticle volume concentrations were utilized. According to the testing findings, the spiral-type flat plate collector is more efficient than the traditional type of collector. When the fluid flow rate was fixed at 2 lit/m, the maximum collector efficiency was achieved for all fluid types. Overall, throughout the experimental test, the efficiency for all working fluids at the optimal 2-lit/m fluid flow rate was 60.3% for water, 66.5% for CuO nanofluids, and 68% for Al2O3 to nanofluid at 0.4% nanoparticle volume concentration. The experimental test results are generally in good accord with the findings of other researchers.