Heat pipe evacuated tube solar collectors (HPETCs) are utilized in solar water heating systems, however, their thermal performance drops due to the intermittency of solar radiation. To overcome this issue, in this study phase change material (PCM) embedded with Copper (Cu) porous metal is directly integrated within the HPETC. For the purpose of comparison, the performance of the proposed system was evaluated in parallel with a conventional HPETC system under similar conditions. The thermal performance of each system is assessed based on the variation of fin temperature, outlet water temperature, exergy, energy efficiency and cost analysis. The results showed that when the value of solar radiation is at its peak, an increase of nearly 21 °C peak temperature was achieved for the evacuated tube filled with PCM + Cu porous metal. After sunset, the fin temperature difference of 36.1 °C was found between the conventional evacuated tube and evacuated tube filled with PCM + Cu porous metal. Moreover, the maximum water outlet temperature difference of 8 °C, 10 °C and 11 °C were found between two systems around at 10 PM on April 9–11, respectively. The proposed system reported maximum energy efficiency of 85.64% while the conventional system reported maximum of 36.91% daily energy efficiency. Lastly, combined system has showed 11.57% and 9.43% saving in hot water production cost for lifetime (Lt) of 5 and 10 years at 5% interest rate, respectively.