Design and Implementation of Solar PV–Battery Backup System using Next Generation PV Modules and LFP Energy Storage System

Abstract

In rapid urbanization and increasing energy demands in metropolitan infrastructure systems such as the Chennai Metro Rail Corporation (CMRL), there is a strong requirement for dependable and environmentally sustainable backup power solutions. Conventional backup systems based on diesel generators and lead-acid batteries are becoming less suitable because of their demerits like high maintenance requirements, shorter operational lifespan, and considerable carbon emissions.  This paper presents a solar photovoltaic (PV)–battery backup system which has a capacity of supplying a 25 kVA critical load for a period of 2 hours during grid power outages. The proposed system discussed in this paper has a configuration consists of a 15 kWp Interdigitated Back Contact (IBC) monocrystalline PV array, a 55–60 kWh LiFePO₄ battery energy storage system (BESS), an MPPT-based solar charge controller, and a 25 kVA hybrid inverter.  Conversion efficiency is increased to a range of 22 to 24% with the choice of IBC Modules, as they help in reducing the front-surface shading losses. The use of LFP Batteries extends the battery life cycle of 2000 to 6000 cycles approximately, thereby providing an improved safety and thermal stability. A calculated arrangement of IBC Solar Panels is found to meet the average energy requirements of a metro rail station. The proposed system is compared with other technologies like NMC Batteries, Lead-Acid Batteries and Polycrystalline PV-based systems, to highlight the superiority of the former in efficiency, reliability and durability. The detailed analysis has confirmed the scalability and practicality of the proposed system as an alternative backup solution for metro rail applications.