In this research, Latent Heat Thermal Energy Storage Systems (LHTESS) containing Nano Enhanced Phase Change Material (NEPCM) in the presence of novel shape finned heat pipe is numerically investigated from the viewpoint of discharging process. In recent years, LHTESS have been used to establish a balance between energy supply and demand. Since conventional PCMs are characterized with high latent heat and low thermal conductivity, these systems are capable of storing large amount of energy, but storage and retrieval processes cannot be achieved in the desired time duration. In this paper, CFD simulation and multi-objective Response Surface Method (RSM) optimization is used simultaneously to find the optimum configuration of novel shaped fin, which is then attached to a heat pipe and immersed into the LHTESS. The performance of finned heat pipe assisted LHTESS is compared to the LHTESS containing NEPCM, and LHTESS with other common fin structures. Since the immersion of finned heat pipe into the system decreases the amount of employed PCM, the maximum energy storage capacity of the LHTESS drops subsequently. Thus, energy storage capacity, as one of the objectives of optimization procedure of this research is studied quantitatively, which is proposed as the novelty here. Results indicate that employing maximum energy storage capacity as an evaluation parameter, leads to efficient design of LHTESS. Also it is inferred that immersing finned heat pipe into LHTESS as a heat transfer enhancement technique is superior to nanoparticles dispersion. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.