This research work presents a study of Low-Voltage (LV) distribution system integrated with Photovoltaic (PV) and Battery Energy Storage (BES) for an urban area in developing country. This work purposes to search an optimal topology and sizing of PV-BES for supplying the consumers. A mixed integer quadratically constrained programming (MIQCP) is developed at first to find out the optimal topology with minimization of conductor use and phase balancing improvement. Next, a maximum PV penetration is sized by using Genetic Algorithm (GA) and Fmincon solver. The sizing strategies are established to determine a BES capacity according to time-varying solar radiation and demand curves. The results obtained on an example of LV test system show the validity of novel algorithm for optimal topology, PV size and centralized BES capacity.