Solar water desalination is still one of the most efficient techniques in water and wastewater treatment. In the present study, an evacuated tube collector (ETC) was used as the basin of the solar still. A cube-shaped glass condenser was attached on top of the ETC for vapor condensation. The main purpose was to investigate the effect of condenser geometry, including volume, surface, and wall thickness on distilled water production. The optimal conditions to produce a maximum volume of distilled water were determined using response surface methodology (RSM), based on the Box-Behnken design (BBD) model. All selected operating factors significantly affect the volume of water produced by solar desalination. The maximum volume of produced water was 7.231 kg.m−2.day−1, which was obtained at the condenser volume of 2940 cm3, the condenser wall thickness of 4 mm, and the condenser surface of 3360 cm2. R2 and Radj2 values in the selected model were 0.9934 and 0.9815, respectively. The validation experiment confirmed the high accuracy of the BBD model for predicting the optimal conditions to achieve the maximum amount of produced water.
