Sun Tracking Based on Hybrid Control with High Accuracy and Low Consumption

Abstract

The concentrator photovoltaic (CPV) system needs a dual-axis sun tracking system with high precision to track the sun position. This is because the power generated by small solar multijunction cells with concentrators lens drops dramatically once the pointing angle position error exceeds maximum acceptance angle of less than 1°. In this present paper, a sun tracking unit based on optimized Hybrid control has been realized to improve the tracking accuracy and reactivity of a dual-axis tracking unit in CPV systems. The hybrid control system including two strategies based on closed-loop algorithm to communicate with LDRs sensors as well as an open loop algorithm based on astronomical equations is implemented and tested. The circuit of the hardware part related to the hybrid sun tracker has been carefully designed in such way the sun tracking continues along azimuth axis and the elevation axis in both clear and cloudy sky throughout the day. We first report the results of experimental analyses and comparison of tracking accuracy between the closed and open loop. Based on these results, the strategy of hybrid solution is proposed and implemented. The results of drivers consumption of the developed hybrid solar tracker indicate a low power consumption with a total energy of 3.66Wh along altitude axis and 3.03Wh along azimuth axis in the day. The tracking accuracy of hybrid control is less than ±0.4° along the two axes.