Selecting a suitable battery technology for the photovoltaic battery integrated module

Abstract

The use of batteries is indispensable in stand-alone photovoltaic (PV) systems, and the physical integration of a battery pack and a PV panel in one device enables this concept while easing the installation and system scaling. However, the influence of high temperatures is one of the main challenges of placing a solar panel close to a battery pack. Therefore, this paper aims to select a suitable battery technology considering the temperature of operation and the expected current profiles. The methodology for battery selection is composed of a literature review, an integrated model, the design of an application-based testing, and the execution of the aging test. The integrated model was employed to choose among the battery technologies, and to design a testing procedure that simulated the operational conditions of the PV-battery Integrated Module (PBIM). Two Li-ion pouch cells were tested at two representative temperatures while applying various charging/discharging profiles. After the testing, the LiFePO4 (LFP) cells showed better performance when compared to LiCoO2 batteries (LCO), where for instance, the LCO cells capacity tested at 45∘C, faded 2,45% more than the LFP cells at the same testing conditions. Therefore, LFP cells are selected as a suitable option to be part of the PBIM.