Shading effect and optimal tilt-angle of collectors in a collector array

In this work, shading effect and optimal tilt-angle of collectors in an array was investigated based on the mathematical method developed. Results show that the distance between collectors in two adjacent raws (D) has a significant effect on the annual collectible radiation, and the ratio of top vertical height of collectors (H) measuring from the ground to D should be larger than tan(23.45+λ). Results also indicate that, the optimal tilt angle of collectors is related to site latitude (λ), climatic conditions in sites, reflectivity of the ground (ρ) as well its position in the collector array, for the case of ρ= 0.2, the optimal tilt-angle of south-facing collectors in the first raw, β _1,opt, is close to the site latitude for most of areas in China except areas with poor solar resources, and the optimal tilt-angle of collectors in other place is about 4-5° lower than β _1,opt; whereas for the case of ρ =0, the optimal tilt-angle of all collectors in the array is almost identical and about 7-8° lower than the site latitude for most areas in China.