In this paper it is presented a mathematical analysis of the energy efficiency for the Multiport Power Converter (MPC) used in series and parallel Hybrid Power Source (HPS) architectures type on the plug-in Fuel Cell Vehicles (PFCVs). The aim of the analysis is to provide general conclusions for a wide range of PFCV operating regimes that are chosen for efficient use of the MPC architecture on each particular drive cycle. In relation with FC system of PFCV, the Energy Storage System (ESS) can operate in following regimes: (1) Charge-Sustaining (CS), (2) Charge-Depleting (CD), and (3) Charge-Increasing (CI). Considering the imposed window for the ESS State-Of-Charge (SOC), the MPC can be connected to renewable plug-in Charging Stations (PCSs) to exchange power with Electric Power (EP) system, when it is necessary for both. The Energy Management Unit (EMU) that communicates with the EP system will establish the moments to match the PFCV power demand with supply availability of the EP grid, stabilizing it. The MPC energy efficiency of the PFCVs is studied when the ESS is charged (discharged) from (to) the home/PCS/EP system. The comparative results were shown for both PFCV architectures through the analytical calculation performed and the appropriate Matlab/Simulink® simulations presented.