This study presents a thermal resistance network (TRN)-based mathematical model to evaluate the thermal performance of an Evacuated Tube Heat Pipe Solar Collector (ETHPSC). The model accurately predicts key performance parameters such as outlet water temperature, evaporator and condenser wall temperatures, useful power, and thermal efficiencies. Parametric analysis reveals that the collector achieves a peak efficiency of 60% under 900 W/m2 solar irradiation with a 20 ℃ inlet temperature and a mass flow rate of 30 kg/h. The study also shows that increasing the water inlet temperature reduces collector efficiency, while higher flow rates affect the outlet temperature with minimal impact on efficiency. Model predictions show strong agreement with experimental data, particularly at lower flow rates. These findings highlight the model’s effectiveness for optimizing ETHPSC design and operation across varying climatic and operational conditions.