Sun Tracking by Peak Power Positioning for Photovoltaic Concentrator Arrays

This paper describes the design, development, and evaluation of a microcomputer-based solar tracking and control system (TACS) for a photovoltaic (PV) concentrator array. The TACS combines the function of sun tracking with the function of load adjustment for peak array efficiency. The complete PV array is used as the sun sensor. The TACS minimizes tracking errors caused by dust and dirt on shadow-band tracking systems, and minimizes the effects of structural warpage and sag that may occur in large arrays. A single-board computer with a specially designed input/output board controls array positioning by an orderly method of stepped movements and finds the peak power point by scanning the current-voltage curve of the array. The TACS was tested using a small two-axis tracking concentrator array. Test results show a deviation in maximum power of less than 1% during the day after accounting for other variations.