DC distribution for residential power networks-A framework to analyze the impact of voltage levels on energy efficiency

DC networks for residential consumers have gained attraction in recent years, primarily due to building-integrated photovoltaics and increasing electronic loads coupled with the decreasing prices of DC appliances. Unlike AC (110V, 60Hz, or 220 V, 50Hz), the existing standards for DC distribution are disjoint, ranging from 48V to 380V with distribution voltage selection affecting the system efficiency. In this work, we formulate a framework to analyze the impact of various voltages on residential system losses incorporating both distribution losses and power electronic conversion losses. Subsequently, we evaluate the system efficiency for a typical DC home at 48 V, 220 V, and 380 V DC and compare it with the 220 V AC using the developed analytical framework as well as through simulation. Results show that for a medium scale solar integrated house, the DC system at 220 V and 380 V is 4% and 10% more efficient than the AC 220 V system, respectively. Further, for 48 V DC, the system efficiency is higher than 380 V DC for wire size AWG-6 and beyond. While the efficiency depends on several factors such as conductor size, voltage selection, loads connected, and the solar capacity, the framework presented is the key in the quantification of losses and selection of suitable system components for DC home. (C) 2020 The Authors. Published by Elsevier Ltd.