In this paper, we propose a numerical study of an integrated collector storage solar water heater .
Two numerical models in three-dimensional modeling are developed.
The first one which describes a sensible heat storage unit , allowing validating the numerical model.
Based on the good agreement between numerical results and experimental data from literature, and as this type of
solar water heater presents the disadvantage of its high night losses, we propose to integrate a phase
change material (PCM) directly in the collector and to study its effect on the ICSSWH thermal performance