Design of the collector in solar air collector dryer (SACD) system is very important factor for high drying performance and the effective use of solar radiation. The main purpose of this study is to increase the thermal efficiency of the solar air collector (SAC) by adding a two-direction solar tracking feature sup ported by programmable logic controller (PLC) to the SAC. A movable SAC and fixed SAC with same dimensions were designed and integrating both collectors into the drying cabinet, generating two different SACDs. Semielliptical sliced products were dried at similar air flow rate and ambient conditions in both drying systems. The results indicated the highest SAC thermal efficiency was 91% in the SACD with solar tracking feature, while the lowest SAC thermal efficiency was 34% in the other SACD. In addition, the drying process in the solar tracking feature SACD was performed with an average drying efficiency of 66%, while the fixed SACD was performed with an average drying efficiency of 32%. Based on the results, the main role of PLC solar tracking feature in SACD system is to increase the average thermal efficiency by 42% and to double the average drying efficiency. (c) 2020 Elsevier Ltd. All rights reserved.