THE EFFECT OF LOW IRRADIANCE ON THE HARMONICS IN STAND-ALONE PHOTOVOLTAIC SYSTEM

Abstract

Photovoltaic (PV) systems have been increasingly used in the generation of electrical energy, either as a means of providing electricity in areas where there is standalone systems, or by providing electricity to the grid connected systems. In this study the effect of low irradiance has been investigated on the harmonic components for standalone PV systems. Pyranometer was installed for controlled data acquisition system and used to collect the spectral irradiance data. It is clear that total harmonics distortion (THD) is very sensitive to be changed in solar irradiance condition. The THD values are high up to 130 % in the morning and evening hours when the solar irradiance is low and also when the solar irradiance is affected by sudden changes like passing clouds. But when the solar irradiance is high during the day, the current THD value gets reduced below the value of 10%. Also, fluctuating solar irradiance resulted in reduction of active power generated by off-grid PV system reducing the overall efficiency of the solar system.