Distribution and optimization of solar radiation in a solar greenhouse under the influence of wall shading

Abstract

In this study, an indoor solar radiation calculation model was established to investigate the horizontal beam and diffuse radiation distributions in a solar greenhouse and their optimization under the influence of wall shading. According to the model calculation results, both the indoor horizontal beam and diffuse radiation were influenced by greenhouse wall shading. The closer the location was to the corner, the lower the received global solar radiation on a horizontal surface. From 08:00 to 16:00 in winter, the position of the solar energy maximum on the greenhouse ground surface gradually moved from southwest to southeast. Then, the concept of the solar radiation utilization efficiency was proposed to explain the indoor horizontal solar radiation distribution differences between the span and length directions. Finally, the horizontal solar radiation variation was studied via dimensionless analysis of greenhouse building parameters. A sloped soil surface was proposed to improve global solar radiation received by the soil surface. On the basis of the dimensionless analysis results, when the length-height ratio was less than 4, ranged from 4 to 10, or greater than 10, there was an obvious shade effect, a weak shade effect, or a negligible shade effect, respectively. At soil slopes of 2.5°, 5°, 7.5°, and 10°, the hourly mean value of the total solar radiation on the soil surface from 08:00 to 16:00 increased by 6 %, 11 %, 15 %, and 20 %, respectively, compared with the original value.