This work focuses on the development of a control and diagnosis-oriented model of a Solid Oxide Fuel Cell (SOFC) integrated system module (ISM). Fuel cell researchers and developers are currently investing significant resources on such fuel cell-based energy conversion systems, as a consequence of their adaptability to a variety of applications and power size. In this configuration, heat exchanges among components are difficult to manage and, consequently, reliable model-based tools are required to enhance the design phase. Therefore, the main heat exchange mechanisms (including radiation, here modeled via view-factors-based approach) are evaluated by simplifying 3-D geometries, as well as assuming the outlet temperature from each component as its state variable. The resulting lumped parameters model was proven effective in achieving the required compromise between accuracy and computational time, particularly in view of its real-world deployment for advanced balance of plant (BoP) analyses, as well as within control and diagnostic model-based tasks. Moreover, the entire SOFC ISM model is generic and can be suitably applied to different layouts, through the characterization of main model parameters. Simulation results are in agreement with experimental data collected on a non-conventional micro-CHP system, named HoTBox (TM), tested under nominal operating conditions within the EU funded project DIAMOND.