In the present work, energy and exergy system analysis are used to estimate the thermodynamic performance of a SOFC system fuelled by methane. More precisely, the present work examines in detail the influence of the presence or absence of the reformer within the whole apparatus and the consequent energy and exergy losses due to the reforming process. The Reforming-SOFC-PP system consists of the SOFC stack, a reformer, an afterburner, two preheaters, a vaporiser and a mixer. Methane and steam are mixed in the mixer and are heated in one preheater up to the operational temperature of the reformer. On the other hand, the Direct-Methane-SOFC-PP consists of the SOFC stack and only two preheaters. The heat produced in SOFC was enough to heat the fuel and the air entering SOFC up to a temperature adequate for the efficient operation of the power plant. It was found that the exergetic efficiency for the Direct-Methane-SOFC-PP is very high (92.5%) compared with that obtained by assuming Reforming-SOFC-PP (66.9%). This, approximately 34%, difference is mainly because of the fewer devices that the Direct-Methane-SOFC-PP consists of, which leads towards the minimisation of the exergetic consumption. Under this respect, the non-reforming case could be considered as the upper limit for the efficiency's of the reforming case, and, obviously, every modification will result in lower efficiencies. Finally, it was stressed that the influence of the fuel utilisation on the cell output is positive in the direction of the maximisation of the energetic and exergetic efficiency.