The aim of this work is to study the effect of truncation of an integrated solar collector with full CPC reflectors on the optical and thermal performances. The design with untruncated concentrator has a strong connection with a previous study where an old ICS system was designed and experimentally tested and it was already studied in a previous work. The upper part contained two symmetrical parabolic sections with focal axes tilted by theta = 48 degrees from the vertical plane. The lower part was constituted by three involute reflectors. Its cylindrical storage tank covered the triangle formed by the three involute parts centers. In order to reduce its size while keeping an acceptable level of the average temperature, minimize its manufacturing cost and facilitate its installation, truncation is suggested. A numerical model based on the detailed geometric characteristics of the full CPC was developed to plot the corresponding profile that was took as reference to switch to a truncated CPC deduced from the latter mathematical equations. A theoretical study was then carried out to predict the optical and thermal behavior of the system and simulate several parameters such as the concentration ratio and the height of the upper concentrating stage. The results are presented and discussed. The developed numerical tool within this work can be considered as important for a future study of the optical performances regarding the angle of acceptance for optimization. (C) 2016 Elsevier Ltd. All rights reserved.