The present study is a continuation of the authors' previous investigations on productivity estimation of portable solar stills utilizing thermoelectric modules (Esfahani et al., 2011; Rahbar and Esfahani, 2012). In this study, a new improved design portable asymmetrical solar still has been designed, fabricated and tested over six typical summer days (between 27/08/2014 and 07/09/2014) under the real climatic conditions of Semnan (35 degrees 33'N, 53 degrees 23'E), Iran. The effect of thermoelectric cooler (TEC) on productivity and performance of the still has been experimentally investigated. The results declared that although the surface of TEC is approximately 2.8 times smaller than that of the glass, its productivity is 3.2 times greater. Furthermore, the start point of distillation on TEC was earlier than that of the glass by 3 h due to its lower temperature. The minimum and maximum daily productivity of the studied solar still was approximately 225 and 500 ml in the solar intensity of 20,500 and 25,500 J/m(2), respectively. (C) 2016 Elsevier Ltd. All rights reserved.