SOFC numerical simulations and experiments are a low cost method hi achieving adequate performance to penetrate the market. Most of the efforts are at the present,focused on components, single cells and stack performances and reliability improvements, while, at the same time, a lot of work is needed,for optimal system configuration design. Simulation and experimental results conducted on a system level must provide a goal and scope of the single components system research, including fuel processing,fuel cells and all the balance of plant (BoP) components. In the present work a preliminary numerical simulation of a SOFC system is conducted, in order to establish the optimal stack size for minimal cost of electricity (CoE) achievements.