In this paper, an innovative longitudinal triangular fin was proposed to improve the solidification performance of shell and tube latent heat thermal energy storage (LHTES) device. At first, the solidification behaviors (solid fraction, temperature distribution and solidification time) of two different layouts of innovative fins (Fin-B, Fin-C) were compared with the traditional rectangular fin (Fin-A). Then, the dynamic temperature response of the fins with superior performance were analyzed. In addition, the influences of the fin geometrical parameters, initial temperature and fin materials on the solidification performance were studied and discussed. The results showed that the innovative longitudinal triangular fins can significantly improve the solidification performance of PCM in LHTES, and the Fin-C had better heat transfer efficiency and superior solidification performance among the three types of fins. The solidification time of Fin-C-I decreased 38.30% significantly compared with the traditional rectangular Fin-A. Generally, the solidification time decreased by decreasing the initial temperature, or increasing the thermal conductivity and the fin heights. However, the effect of the bottom width of triangular fin on the solidification performance can be neglected. To achieve a faster cooling rate, the recommended temperature difference between the inner wall and PCM was over 20 K. (C) 2019 Elsevier Ltd. All rights reserved.