The planar solid-oxide fuel cells (PSOFCs) haveemerged as one of the promising candidates forfuture energy system because of their high energyefficiency, fuel flexibility, zero emission,modularity and high tolerance to the fuelimpurities.However, for large-scale commercialization of thePSOFC technology, there is a strong need ofdeveloping a reliable and highly efficient PSOFCpower system. Development of such a reliable PSOFCbased power system requires knowledge of the severalfeedback effects from the power electronics systemand the application loads that may impact the PSOFCstack and the system as a whole. Therefore, it isimportant to develop analytical methodologies toinvestigate and mitigate the effects of theseelectrical feedbacks on the performance of PSOFCsystems.On the whole, the dissertation focuses on i) themodeling and development of an effective PSOFC power-system design and system interaction analyses, ii)cost-constrained PES topology design for PSOFCS andiii) the design of cost effective optimal controllerand controlling strategy for mitigation ofelectrical impacts with higher system efficiency.