In the present study, different thermal oil-based hybrid nanofluids (Al₂O₃+Ag+therminol-VP1, Al₂O₃+Ag+Paratherm-CR, Al₂O₃+Ag+Dowtherm-Q) has been used as a primary fluid in the passive indirect solar water heating (PISWH) system. The performance of the passive indirect solar water heating system has been evaluated by using three performance parameters i.e mass flow rate, effectiveness of the heat exchange and total entropy generation rate of the system for the laminar flow regime. The effect of geometric parameter such as tube diameter (25, 30, and 35 mm), solar collector inclination (θ=300,450,600) and different type of heat exchangers (Tube in Tube, Shell and Tube and Plate type) on the performance parameters has been studied. The study reveals that the mass flow rate increases with increasing diameter of tube and collector inclination angle. Whereas, the effectiveness decreases with increasing tube diameter and collector inclination angle. Moreover, the total entropy generation rate increases for increasing tube diameter and collector inclination. Therminol-VP1 hybrid nanofluid and plate heat exchanger show the best performance among oil-based hybrid nanofluids and heat exchangers.