High accuracy sun-tracking using CCD and field test for PV system

Tracking photovoltaic (PV) and concentrator photovoltaic (CPV) can enhance electricity output by either single or two-axis sun-tracking. In addition to solar irradiation, tracking accuracy is fundamentally important to the performance of PV/CPV system. We developed a technique using the CCD apparatus for accurate sun-tracking and monitor its outdoor performance on a two-axis tracking PV system. The apparatus consists of a closed-loop solar tracker based on light sensor and 9 PV modules. The processing speed of the apparatus is upto 0.03 s which sufficient for operating in outdoor test (10-30 s is required). The view angle is 7.6° and angular resolution is 0.008° by using a lens of 50 mm (aperture F2.8). The outdoor test for sun-tracking is performed on a period of six days with sunny and cloudy weather and satisfactory results were obtained with 92% of the distribution of offset angles smaller than 0.3°.