Phase change materials are shown to be an effective means of limiting temperature rise in photovoltaic devices. A three-dimensional (3D) numerical model was developed to simulate the use of a phase change material linked to a PV system to control the temperature rise of the PV cells. The model can be used to predict temperatures, velocity fields, and vortex formation within the system. The predicted temperatures using the 3D model have been compared with experimental measurements for which the system geometry, material characteristics, and boundary conditions have been matched as closely as possible. The 3D predictions have also been compared with those from a previously developed and experimentally validated two-dimensional (2D) finite-volume heat transfer model conjugated hydrodynamically to solve the Navier-Stokes and energy equations. It was found that for the systems simulated with appropriate boundary conditions, the 2D model predictions compare well with those of the 3D model. Using the 3D model, the temperature distributions were predicted when the heat transfer to the PCM was enhanced by high thermal conductivity pin fins. The effects of the container boundaries have been analyzed.