The presented work represents one part of the accurate studies led in a French Integrated Research Project supported by the CNRS. The context of this study is related to the integration of a combined photovoltaic-thermal ( PV-T) collector as a component of buildings' facades. This concept is developed so as to determine the best integration strategy - to make the most efficient use of a solar energy-collecting surface in terms of both electrical conversion and air heating, taking into account the fact that thermal effects help to maintain the PV module operating temperature at an optimal level for photovoltaic conversion. To achieve these objectives, one of the key issues is to understand and analyze the coupled physical mechanisms governing the thermal behavior of combined PV-T collectors. In this paper, models describing conduction and radiation heat transfer in a PV module, which govern the thermo-aerodynamics in the air channel, are detailed. For the fluid flow modeling, a low Reynolds number model is applied, and particular attention is paid to the best choice of associated parameters. In the case of a vertical channel heated at one side, a parametric study is performed as a function of the channel width, wall heat flux, and dimensionless turbulent intensity. A preliminary application of the coupled radiation - the natural convection heat transfer problem corresponding to a photovoltaic-thermal collector configuration - is proposed.