Development of an embedded solar tracker for the enhancement of solar energy utilization

An embedded two-axis solar tracking system using Laboratory Virtual Instrumentation Engineering Workbench to write the operation and control algorithms was developed for enhancing solar energy utilization. The system consists of a real-time processor, two motion-control modules, two step drives, two step motors, feedback devices, and other accessories needed for functional stability. The real-time processor allows the solar tracker to be used as a stand-alone, real-time system that can operate automatically without any external control. The system combines two different solar tracking methods: the optical method and the astronomical method. Cadmium Sulfide (CdS) sensors are employed to continuously generate feedback signals to the controller, ensuring high-precision solar tracking even under adverse conditions. The CdS sensor is a resistor whose electric resistance decreases with increasing incident light intensity. A database of solar altitude, azimuth, and sunrise and sunset times is provided by this solar tracking system. Other solar trackers operating in an astronomical method may access and use this database over the Internet. Solar position and sunrise and sunset times in the database were compared with those of the Astronomical Applications Department of the U.S. Naval Observatory. The differences were found to be negligible. Copyright (C) 2011 John Wiley & Sons, Ltd.