This paper reviews recent progress and applications of CNT nanofluids in energy harvesting system especially solar collectors. In addition to reviewing the efficiency of solar collectors which use CNT nanofluids, the paper also discusses the preparation methods, factors for enhancing thermal conductivity and optical properties of CNT nanofluids. Finally, the challenges and future trends related to the application of CNT nanofluids in thermal solar collector is discussed. (C) 2017 Elsevier Ltd. All rights reserved.