Modular battery-integrated bidirectional single-stage DC–DC converter for solar PV based DC Nano-grid application

Abstract

Attributed to the growing focus on energy savings and eco-friendliness, the solar PV-based DC Nano-grids for residential and commercial buildings are becoming more popular. On the other hand, solar photovoltaic systems (SPV) are intermittent and unreliable due to their dependency on external factors such as solar irradiance, ambient temperature, and unpredictable shadows. In addition, the power degradation occurs in SPV systems due to module mismatch losses caused by various factors like partial shading (PS), dissimilar aging effect, different power ratings, etc. The conventional PV system cannot handle all these issues, so it is essential to address them. This paper proposes a bidirectional modular PV battery system (BMPBS) that uses non-isolated buck and boost converter combinations. This system is capable of self-sustained generation, storage, and bidirectional power flow within the Nano-grid. The proposed BMPBS can handle losses due to module mismatch and intermittency in SPV with the help of battery storage system (BSS), making the overall SPV system reliable. It requires single-stage power conversion to extract maximum power from each PV module and BSS charging and discharging. Its modular design allows it to function across various voltage, power, and BSS choices. This paper discusses the operation, steady-state analysis, and dynamic analysis of the proposed BMPBS. The performance of the proposed BMPBS is validated using a state-of-the-art experimental setup with two PV modules, each having a rating of 90WP.