Critical Evaluation of Offline MPPT Techniques of Solar PV for Stand-Alone Applications

This paper critically presents the analysis of the performance of offline maximum power point tracking techniques such as voltage-and current-based MPP technique, look-up table method, and curve fitting-based MPP technique. Based on the analysis presented in the paper, authors have selected offline voltage-based MPPT technique for using in their modeling and simulation study for stand-alone applications. An offline voltage-based MPPT technique which is capable of tracking MPP has been selected because of numerous advantages it offers such as simple and low cost of implementation. The modeling has been done in MATLAB (R) / SIMULINK simulation environment, and MPPT technique is developed and implemented by taking a variable resistance as a load. To remove the limitation of the momentarily interruption in power delivery to the load due to measurement of the open circuit voltage (V-oc), a pilot PV panel of same rating to that of main PV panel is used in the paper to calculate V-oc. It resulted in an increase in efficiency as more energy can be delivered to the load as the main panel is never disconnected to calculate Voc. The simulation results are presented and discussed in the paper, and the results shows that the MPP is tracked under changing atmospheric conditions such as variation in temperature and insolation. The study presented in the paper will help the researchers/engineers/professionals in the industry to implement the MPP technology at large scale thus making India a self-reliant country on tapping solar energy resources.