An investigation on daylight in PV greenhouse for mushroom vertical cultivation in Kunming, China

Abstract

Recently, there has been an increasing emphasis on generating energy from renewable sources, resulting in the installation of photovoltaic (PV) modules on the roofs of agricultural greenhouses. The optimal combination involves integrating a photovoltaic greenhouse with vertical growing of edible mushrooms. This synergistic approach allows for increased planting capacity and enhanced exploitation of solar radiation. However, there is very little progress in the evaluation of spatial light for such photovoltaic planting systems. This study examined the amount of daylight accessible in a photovoltaic greenhouse for mushroom vertical cultivation in Kunming, China. The spatial intensity of daylight was simulated with RADIANCE, a software application that simulates solar and light rays by ray-tracing. The findings indicated that the average disparity in sunlight intensity between each layer of the shelf of edible mushroom, when arranged in an east–west or north–south orientation, was below 9% at noon. However, the latter configuration resulted in a more even distribution of daylight in the greenhouse. The shading percentage remains relatively consistent during the four significant days of spring equinox, summer solstice, autumn equinox, and winter solstice. On the summer solstice, the shadow range is primarily concentrated in the greenhouse due to the elevated position of the sun. This leads to a lack of consistent lighting across different heights within the greenhouse. As the solar altitude angle decreases, the intensity of light decreases but the light inhomogeneity increases. These findings have the potential to be used as design techniques for supporting vertical planting in PV greenhouse planning.