© 2021 Elsevier LtdThe increase in the gap between energy supply and demand have led to human focus on energy storage. With this purpose, this study numerically investigates the melting process of phase change material (PCM) in a storage by inserting innovative fins, which are combination of rectangular and triangular fins. Left wall of storage is assumed to be at a constant temperature which is higher than the melting temperature of PCM. The impacts of various efficient parameters on melting process are evaluated, which are schematic of internal fins, height of triangular fins, hot wall temperature, and different types of PCM. Results showed that among various studied geometries of fin, the proposed one herein augments the melting rate by about 57.56%. As the number of fins increments, melting time decreases, which leads to higher energy charging rate. By arrangement of triangular fins with different heights (ascending or descending) the melting time can be further shortened. The temperature of hot wall is inversely related to melting time, i.e., the higher hot wall temperature is, the shorter melting time is. Among evaluated PCMs, paraffin wax 811 showed better thermal performance with lower melting time and higher stored energy in a certain period of time.