Optical performance of vertical axis three azimuth angles tracked solar panels

In this work, a new sun-tracking concept was proposed, and the optical performance of solar panels with such sun-tracking system was theoretically investigated based on the developed mathematical method and monthly horizontal radiation. The mechanism of the proposed sun-tracking technique is that the azimuth angle of solar panels is daily adjusted three times at three fixed positions: eastward, southward and westward in the morning, noon, and afternoon, respectively, by rotating solar panels about the vertical axis (3A sun-tracking, in short). The analysis indicated that the tilt-angle of solar panels, β_3A, azimuth angle of solar panels in the morning and afternoon from due south, φ_a, and solar hour angle when the azimuth angle adjustment was made in the morning and afternoon, ω_a, were three key parameters affecting the optical performance of such tracked solar panels. Calculation results showed that, for 3A tracked solar panels with a yearly fixed tilt-angle, the maximum annual collectible radiation was above 92% of that on a solar panel with full 2-axis sun-tracking; whereas for those with the tilt-angle being seasonally adjusted, it was above 95%. Results also showed that yearly or seasonally optimal values of β_3A, φ_a and ω_a for maximizing annual solar gain were related to site latitudes, and empirical correlations for a quick estimation of optimal values of these parameters were proposed based on climatic data of 32 sites in China.