Optical performance of vertical single-axis tracked solar panels with seasonal adjustment of tilt-angles

To investigate the optical performance of vertical single-axis tracked solar panels with the tilt-angle of solar panels being seasonally adjusted (4T-V-A tracked solar panels, in short) as compared with fixed and full 2-axis tracked solar panels, a mathematical procedure to estimate the daily collectible radiation on fixed and tracked panels is suggested based on the monthly horizontal radiation. Calculation results showed that the optimal date on which tilt-angle adjustments were seasonally made was about 23 days from the equinoxes, the seasonal optimal tilt-angles of a 4T-V-A tracked solar panel for maximizing seasonal energy collection strongly depended on site latitudes, and the corresponding maximum annual collectible radiation on such tracked panel was about 97% of solar radiation annually collected by a dual-axis tracked panel, slightly higher than that on those tracking the sun about south-north axis inclined at a yearly fixed tilt-angle from the horizon. Empirical correlations for a quick estimation of seasonal optimal tilt-angle of vertical single-axis tracked solar panels were also proposed based on climatic data of 32 sites in China.