Composite materials based on expanded natural graphite (CENG) and various phase change materials (PCM) have been developed for low temperature solar applications (323-373 K). The integration of such composite materials directly into the solar collector could allow new storage functionality. A numerical model has been developed to describe the materials behaviour. Composites properties are presented and discussed. (C) 2008 Published by Elsevier B.V. on behalf of The Institution of Chemical Engineers.