•Transforming continuous fin into discontinuous fins enhances heat transfer in PCM.•The use of discontinuous strip fins can improve the energy release time by up to 89%.•89% time improvement was achieved by an optimum distribution of the strips fins.•89% time improvement was achieved when only 2% strip fins were employed.•Fin material is one of the effective parameters in discontinuous fins.•Using nanoparticles alone cannot lead to a significant improvement in phase change time. Energy storing is one of the most vital needs in the energy industry. This paper aims to solve the problem of long energy release time in phase change material (PCM) energy storage system. In the present study, continuous longitudinal fin that had been traditionally used in literature is transformed into a new three-dimensional distribution of discontinuous strip fins. Effects of the geometric distribution of the strip fins, fins material and adding nanoparticles (NPs) to the PCM on heat transfer enhancement and energy discharge time are investigated by testing 17 different cases. According to the results, the use of discontinuous fins can improve the energy release time up to 89% and 84% comparing to continuous copper and aluminum fins, respectively. Moreover, the results indicate that effect of fin material on the thermal performance is insignificant in cases of continuous fins. The results confirmed that the optimal distribution for cases of discontinuous aluminum fins with and without NPs is different. Besides, the maximum of saving discharge time is 77.8% and 59.5% for combination of NPs with copper and aluminum discontinuous fins, respectively. Besides, the results show that the application of nanoparticles alone cannot lead to a significant discharge time improvement.