This paper describes a baseline solution of a Power Conditioning and Distribution Unit (PCDU) for Electrical Propulsion (EP) systems. The solution adopted uses two high efficiency, low-mass power regulators; a solar array regulator (SAR) based on the classical Sequential Switching Shunt Regulator with Maximum Power Point Tracking (MPPT) capability followed by a step-up converter to achieve the desired regulated bus voltage. This paper focuses on the first part of the PCDU, the Sequential Switching Shunt Maximum Power Regulator (S3MPR). This electrical architecture has been adapted and recently proposed for the Electric Propulsion power system of the European and Japanese Mercury Mission (BepiColombo). A scaled-down electrical model of the proposed system has been manufactured in order to prove the concept.