PERFORMANCE INVESTIGATION OF PHOTOVOLTAIC SYSTEMS UNDER PARTIAL SHADING CONDITIONS

Abstract

Among all renewable energy sources, solar energy is considered most popular source due to its superior quality and abundant availability. The solar energy is used as an input energy with solar thermal energy systems and solar photo voltaic (SPV) systems. SPV systems have easy installation, require less maintenance and free from environmental issues. PV systems are composed of PV cell and a typical PV cell can produce very less power and to increase the power production, cells are configured to form modules and modules are arranged to constitute arrays. As power produced by PV array depends on the environmental conditions, it is therefore important to investigate the PV performance in terms of reliability and accuracy in simulated environment to predict the power production. To predict the performance of PV module, a reliable and accurate simulation design of a PV generator afore its implementation in real practice is required. The output voltage and current depend on the solar irradiance, ambient temperature, and load. To investigate the effect of cell failure, module mismatch, partial shading on PV array and to analyze maximum power point tracking (MPPT) techniques afore its use in real practice, it is a prerequisite to simulate the complete electrical characteristics accurately and efficiently. Lumped circuit models are widely used for assessing cell performance and for complete characterization of PV modules. Single-diode model and Double-diode models are the lumped models which are extensively used as equivalent electrical circuit for a PV module. The complete physical characteristics of PV modules are represented by equivalent electrical circuit models and its parameters i.e. photo current (Iph), saturation current (I0), series resistance (RS), shunt resistance (RP) and ideality factor (a1). These parameters are not given in manufacturer’s data sheet specifications. Extraction of PV module parameters includes the evaluation of equivalent circuit parameters in order to simulate the output characteristics of PV module at varying irradiance and temperature.