Planar-solid-oxide-fuel-cell stacks (PSOFCSs), in PSOFC-based power-conditioning systems (PCSs), are subjected to electrical feedbacks due to the switching power electronics and the application loads. These feedbacks (including load transient, current ripple due to load power factor and inverter operation, and load harmonic distortion) affect the electrochemistry and the thermal properties of the planar cells thereby potentially deteriorating the performance and reliability of the cells. In this paper, a detailed study on the impact of these electrical effects on the performance of the PSFOC is conducted. To analyze the impact of such feedbacks, a spatiotemporal numerical system model is developed on a low-cost Simulink modeling platform and the model under transient and steady-state conditions is validated experimentally. Using this validated model, parametric analyses on the impacts of transience, power factor, and distortion of the application load as well as low-frequency current ripple is conducted. Finally, using experimental data, we demonstrate the long-term impact of two most significant electrical feedbacks on the area-specific resistance and the corresponding loss of effective stack power.