Sungrow Power Indonesia is planning to develop several PV Farm equipped with battery located in eastern part of Indonesia. In doing so, Sungrow has appointed Tractebel to do a consultancy service of feasibility study for these projects. One main part in Feasibility Study is power system study which will be done by TE’s partner, Quadran Solusi Enjinering (QSE). QSE is tasked to do battery verification and power system study of Likupang, Kefamenanu, and Rote. Intermittency and resource availability are two of the main challenges in PV farm operation. Its power fluctuation can disrupt the grid frequency, which can be a problematic case for a safe and reliable grid operation. Furthermore, its power which is naturally generated only during the day, cannot be used to fulfill the peak demand which usually happen in the night. Hence, BESS is installed to solve these problems so that its intermittency will not affect system performance and its energy can be shifted to supply the demand during the night. To ensure a smooth operation of soon to be constructed PV+BESS, grid impact study for the plant interconnection to the power system is essential, by conducting the study we will be able to determine the optimum BESS sizing and to assess the technical feasibility of the Solar power plant interconnection from the electrical aspect.