Thermal management of photovoltaic panels (PVPs) with phase change materials (PCMs) is prevalent since PCMs keep the PVP temperature within a certain temperature range while undergoing reversible charging/discharging cycles throughout a day. Even though there is a vast number of numerical works that deal with the modelling of PVP/PCM under various conditions, the majority of the models neglects the convection within the liquid PCM. The current study aims to present the limitations of the PVP/PCM numerical models which are based on heat conduction. A numerical code is developed in C + +, and a survey is conducted under constant and variable boundary conditions. The maximum, average and time-wise variations of the PVP temperatures are presented for conduction and convection dominated models. Results reveal that the conduction and convection dominated models diverge from each other as the PCM thickness is increased. For 10 cm of PCM, the difference between the conduction and convection dominated models is nearly 50% regarding the maximum PVP temperature. Further comparisons are represented regarding the interface growth and liquid fractions to provide an in-depth understanding.