This work aims to evaluate the performance of a solar domestic hot water (SDHW) system including a latent storage material. The originality of our approach consists to place a composite made of compressed expanded natural graphite (CENG) and phase change material (PCM) directly inside a flat plate solar collector in order to replace the traditional copper-based solar absorber. According to this target, the study is composed of two steps: the composites preparation and characterization; and the analysis of the system to achieve optimal integration of the material in the process. The present paper is focused on the selection of the most promising composite to implement in the solar collector. In order to reach this objective, several composites based on CENG and various storage materials (paraffin, stearic acid, sodium acetate trihydrate and pentaglycerin) have been elaborated and characterized. The synthesis of all these measurements allowed us to select three composites whose characteristics match their integration into a solar thermal collector. (C) 2011 Elsevier Ltd. All rights reserved.