A Review of Battery Energy Storage Systems for Residential DC Microgrids and Their Economical Comparisons Udayanka G.K. Mulleriyawage and Weixiang Shen Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC 3122, Australia Abstract In residential DC microgrids integrated with renewable energy sources (RESs), prosumer’s power generation and load demand are not matched due to inherent sporadic nature of RESs. One way to address this issue is to add an energy storage system (ESS). The ESS is useful in fluctuation suppression, load following, time shifting, peak shaving, energy saving and emergency power. Moreover, an ESS will resolve overvoltage issue in utility grids due to exported surplus energy from residential RESs. Therefore, this paper will review battery ESSs that can be used in residential DC microgrids. Three major battery chemistries, i.e. lead- acid, lithium ion (Li-ion) and Zinc bromine (ZB) are reviewed. The analysis of the levelized cost of energy reveals that lead-acid batteries are economically less competitive compared with Li-ion and ZB batteries in residential DC microgrid applications. Keywords: residential DC microgrids, battery energy storage systems (EESs), prosumer and levelized cost of energy (LCOE). 1. Introduction The depletion of fossil fuels and environmental concerns are driving scientific society to conduct more research on renewable energy generation and its integration into existing electricity distribution systems. In this context, the microgrid notion comes into the picture. A microgrid is defined as a collection of distributed generators (DGs) and loads placed within an explicitly demarcated border that can be controlled as a single unit with respect to grids. The microgrid may connect or disconnect from grids to operate in either grid-connected or islanded mode [1]. Accordingly, a residential microgrid can be defined by limiting the border of a microgrid to a single house. AC electricity being the choice for residential electricity distribution for decades. However, DC electricity is gaining its ground, as there are many favoring factors such as the increased popularity of DC-based renewable energy sources (RESs), battery energy storage systems (ESSs) and home DC appliances including LED lighting systems, laptop computer, IPad, mobile phone and many other portable electronic devices. Furthermore, energy efficiency improvements which can be achieved by DC compared to AC distribution [2,3] and anticipated increase of electric vehicles (EVs) penetration [4] are likely to boost DC electricity demand. On the other hand, it is convenient and quite efficient to couple DGs such as photovoltaic (PV) panels and fuel cells (FCs) to a DC distribution system directly or through power electronic converters (PECs) [2]. In addition, high-frequency AC generated by wind turbines can be linked to a DC bus much easier compared to an AC bus, where it requires a synchronized AC voltage. Therefore, residential DC microgrids are in focus for the current study. Figure 1 Key Components of a residential DC microgrid An envisioned residential DC microgrid is illustrated in Figure 1. It consists of RESs (PV panel, wind power source, FC), AC or DC loads, a battery ESS, an EV, and a control system [3]. RESs and battery ESSs are interfaced to a common DC bus in parallel via PECs. To maintain power quality and voltage regulation at the common DC bus, a control system is required. A broad 2018 Joint International Conference on Energy, Ecology and Environment (ICEEE 2018) and International Conference on Electric and Intelligent Vehicles (ICEIV 2018) ISBN: 978-1-60595-590-2