Solar drying devices are mainly divided into the natural convection solar drying, the forced convection solar drying, the mixed mode drying and the joint drying [3]. The natural convection solar drying, also named as passive drying, means that hot air finishes the drying process by natural circulation, with simple structure, cheap price and low efficiency. The forced convection solar drying, also called as active drying, means forcing hot air to circulate for finishing the product’s drying process, with complex structure, high efficiency and high equipment cost. The mixed mode solar drying refers to the mode combining the natural convection solar drying with the forced convection solar drying, and is a kind of more popular drying mode. The joint drying refers to the mode combining solar energy with other heat energy, for example, the solar drying with heat storage device, solar energy-hot pump joint drying, solar energy-heat pipe joint drying, etc. with the maturing and development of solar drying technology and other energy technology, the joint drying obtains rapid development and has become a new drying mode.