A Battery Capacity Configuration Method of a Photovoltaic and Battery System Applied in a Building Complex for Increased Self-Sufficiency and Self-Consumption

Abstract

Photovoltaic (PV) systems have been growing in popularity as an energy conservation and carbon reduction approach. Generally, battery storage is integrated with a PV system to solve the intermittent and fluctuant problems of solar resources, enhancing the relative independence of the PV–battery (PVB) system. In consideration of the economic benefits and system efficiency, it is necessary to investigate battery capacity allocation methods. A battery capacity configuration method was established in this study to increase the self-sufficiency rate (SSR) and self-consumption rate (SCR) of the system for a building complex by exploiting the battery resources. The PVB system designed for the building complex is divided into two categories: distributed and centralized storage. The SSR and SCR significantly increase with the increasing battery capacity for both schemes. The SCR of centralized storage is always higher than that of distributed storage, considering different battery and PV capacities. However, the SSR of distributed storage scheme was found to be slightly higher than that of the centralized storage scheme when the energy generated by PV is half of the energy consumed by the building load. For instance, when the battery capacity is four, SSR values for optimal distributed and centralized storage schemes are 47.62% and 47.19%, respectively. For the distributed storage scheme, there is a slight difference between the optimal allocation ratios achieved by SSR and SCR, considering that they have the same total battery capacity. In addition, the effects of converter loss, complementarity in load curves, and centralized batteries were analyzed to achieve greater SSR and SCR. The comparison results of this study can be used as a guide for battery capacity design in the PVB systems of building complexes.