This paper investigates an evacuated heat pipe solar collector (HPSC) experimentally. The main aim was to study the efficiency of the HPSC. An experimental apparatus for testing solar heat pipe collectors was designed and built at Vali-e-Asr University. By using the two-step method, copper oxide and deionized water was prepared. The structural and optical properties of the nanostructure were characterized by means of X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), scanning electron microscopy (SEM), and UV-visible analysis. Water or MgO-water nanofluid with varying concentrations was used as working fluids. The effect of the working fluid flow rates was also investigated and discussed. The effect of concentration of nanofluid was studied experimentally on the performance of solar heat pipe collector. The thermal performance of HPDC is determined through the experimental results by using this apparatus. The results reveal that the efficiency of the collector increases as the coolant flow rate increases. The efficiency of the heat pipe solar collector with MgO nanofluid is higher than ones with pure water. Also, performance enhances with the increase in the concentration of the nanofluid.