This paper presents the results of an experimental study of a PV/diesel hybrid system without storage. Experimental results show that the sizing of a PV/diesel hybrid system by taking into account the solar radiation and the load/demand profile of a typical area may lead the diesel generator to operate near its optimal point (70-80% of its nominal power). The present paper shows that for a reliability of a PV/diesel hybrid system, the rated power of the diesel generator should be equal to the peak load. By the way, it has been verified through this study that the functioning of a PV/diesel hybrid system is efficient for higher load and higher solar radiation. (C) 2010 Elsevier Ltd. All rights reserved.