This paper presents a thermodynamic analysis of the drying of bananas inside a small-scale prototype solar updraft tower in Belo Horizonte, Brazil. A model based on the first and second laws of thermodynamics was developed, using the ambient conditions and airflow parameters data obtained in the experimental prototype. The exergy rates were determined, and it was concluded that the incident solar radiation plays an important role on the drying process of bananas, the higher the solar radiation, the higher the exergy rates. The exergetic efficiency was compared to that obtained without products inside the solar updraft tower, and it was found that the exergetic efficiency increased from about 20% to 27% with load. (C) 2017 Elsevier Ltd. All rights reserved.