Thailand is a largest exporter of rubber products in the world. One third of them are ribbed smoked sheet (RSS) which have to use biomass for transforming them. Meanwhile, in Thailand, level of solar radiation is very high all year round. If solar energy is used for RSS transforming therefore renewable energy can play a vital role in the primary rubber industry. This research thus focuses on the feasibility study of solar energy use in drying. The mathematical model of drying is developed to study the effectiveness of water-air solar collector coupled with a drying chamber sandwich greenhouse located in Khon Kaen, Thailand. Heat from the greenhouse and the collector is used for drying at the day and night time respectively. A computer program is used to predict drying chamber temperatures as a function of various design parameters of the collector and drying chamber. From the simulation results, it was found that greenhouse could heat up the chamber temperatures in the range of 40°C to 60°C in the day time which is the appropriate temperature for drying rubber. At night time, the collector can heat up temperature over 10°C higher than surrounding.