In this study, the electrical performance degradation of photovoltaic modules (UDTS-50) functioning for a period of 11 years in a region of the Sahara (URER-MS ADRAR) is analyzed. This paper is devoted to an experimental study of current-voltage characteristics of several PV modules exposed to the extreme weather conditions in desert area. The electrical performance degradation and failure modes are estimated from series of current-voltage characteristics performed in the field. Experimental results show that some PV modules degrade up to 12% compared to their initial state. The performance analysis of the others tested modules revealed some defects, such as cracked cells and physical material defects. The identification of the origin of degradation and failure modes and how they affect the photovoltaic modules is necessary to improve the reliability of photovoltaic installations. (C) 2014 Elsevier Ltd. All rights reserved.