Design and Construction of a Sun Tracker System with Analog-Digital Combination Control Method and Feasibility of its Using in Solar Crop Dryers

To increase energy efficiency of solar collectors, reduction in their effective area due to sun motions in the sky can be prevented by tracking of sun path. In this regard, a prototype active sun tracker system, based on microcontroller and electro-optical sensors was designed and constructed. Driving motors were of the stepper motors. Sensors selected from solar cells and system control method was combination of analog-digital controls. In order to evaluating system, the output voltage of a solar module in fixed and tracking states, both in laboratory and real conditions was used. The results showed that the tracking system was more effective in collecting solar energy than fixed one. This system tracked the sun with ±2.5° precision and kept the collector perpendicular to sun radiation. Also the output power during the day, excluding drops in dawn and dusk that was the result of radiation crossing through a thick atmosphere layer, remained approximately fixed. Finally a suggested design of this system for using in crop dryers presented.