Solar water heaters are good tools for saving fuel. The main component of these water heaters is collectors, which are responsible for absorbing solar energy AND transferring it to the working fluid with the least heat dissipation. The present study is an EXPERIMENTAL study of the performance of the solar SEMIspherical collector with 1 m2 of absorber area at different volumetric flow rates. Water was used as the working fluid with the volumetric flow rate between 0. 005-0. 0166 kg/s, AND the experiment was conducted in the ASHRAE 93 stANDard conditions. The results showed that the efficiency of SEMIspherical solar collector increased as the flow rate of the working fluid increased, such that the highest efficiency, which is 67 %, belonged to mass flow rate 0. 0166 kg/s. In addition, the difference between outlet AND inlet temperatures decreased due to the system being closed during the test. In addition, according to the experiments, the reduction of radiation AND wind speed did not have any significant effect on the efficiency AND outlet temperature of the collector. Finally, parameters such as inlet AND outlet temperature of collector, ambient temperature, ambient radiation intensity AND their effect have been investigated empirically on the collector efficiency graph.