Fuel cells are highly efficient energy conversion systems that have recently gained significant interest in terms of both science and applications. Exergy analysis is adopted here for a power plant involving SOFC with external steam reforming that is fuelled by modeled biogas/steam mixtures. The electrical efficiency has been estimated and the effect of various operational parameters on the process efficiency has been investigated. The optimal operation parameters of the integrated SOFC plant are specified by pinpointing and minimizing the existing losses, while a parametric analysis has been also performed to provide guidelines for practical design.