An Experimental and Comparative Analysis of the Battery Charge Controllers in Off-Grid PV Systems

The study of the battery charge process as the only power storage agent in off-grid systems is of significant importance. The battery charge process has different modes, and the battery in these modes is dependent on the amount of charge. In order to charge the battery in off-grid systems, two charge controllers including Pulse Width Modulation (PWM) and Maximum Power Point Tracker (MPPT) are commonly used. The charge rate (C-Rate) is different in these two models. Therefore, it is necessary to study the state of charge (SoC) in the PWM and MPPT models considerably. In this study, by using these two charge controller models, C-Rate is examined on portable and power plant scales. This research indicates that the PWM charge controller has better performance on the power plant scale than on the portable scale. The charging quality of the MPPT model is about 31 % and 7 % on portable and power plant scales, respectively, proved to be higher than that of the PWM charge controller. The PV panel performance has increased by 2 %-5 % through the application of the MPPT charge controller, compared with the PWM model. As the overall achievement of the experiment, according to the limitations of the MPPT charge controller, the PWM charge controller can be proposed on power plant scales, whereas the application of the MPPT model is appropriate for specific purposes.

Keywords:

Charge mode , Charge rate (C-Rate) , State of Charge (SoC) , pulse width modulation (PWM) , Maximum Power Point Tracker (MPPT)