In recent years, a good number of research works have been conducted to elucidate the different aspects of photovoltaic thermal (PV/T) technology. However, in order to take a technology to its maturity level, it is important to explore its internal physics and identify the factors that control system performance. With this view, in the present research, thermal and heat transfer characterization, and pressure drop phenomena inside a parallel-plate PV/T collector have been examined numerically to portray the thermo-fluid physiognomy of the system. A three-dimensional mathematical model of the PV/T system has been developed, and the model is used to build a computer simulation of the system in COMSOL Multiphysics® software. Hence, the simulation model has been validated by outdoor experimental results and was found to be in good agreement. Thus, the simulation program is employed to produce temperature distribution and heat flow plots throughout the flow channel, wherein results have been evaluated for two different channel materials, e.g., aluminum and copper. Results show that heat flowrate through both aluminum and copper channels is virtually the same. On the other hand, pressure drop, thereby pumping power required to maintain flow, is greater for an aluminum channel. The developed heat transfer simulation model can be extended for other PV modules with diverse designs and materials of the heat exchanger.