The intermittent nature of renewable energies may hinder their rapid growth. To overcome this challenge, novel energy storage methods or enhancements to existing ones are required. Thermal energy storage has been extensively studied as a potential solution to this issue. These systems can be used in conjunction with concentrated solar power, where molten salt is used as a heat transfer fluid. However, molten salt is the most expensive component of these systems. Therefore, in recent years, alternatives have been studied where only a single tank is needed, and a solid filler and encapsulated phase change material (EPCM) is used to substitute a part of the fluid. A promising alternative that has emerged in recent years is the use of structured solid filler materials made from waste materials such as ceramics or concrete [1]. A promising approach to advance the development of structured thermoclines is to integrate EPCM into this innovative type of system. The objective of this study is to develop a mathematical and numerical model that couples the EPCM, in both spheres and tubes, with structured thermoclines. The model involves a one-dimensional discretization of the structure containing filler material, while a two-dimensional discretization of spheres or tubes is applied in the EPCM regions. The energy equation is solved using an enthalpy method to account for phase change. Unlike other two-dimensional EPCM models in the literature [2], the innovative aspect of this model lies in its capability to account for volume changes of EPCM inside the spheres or tubes during the transition from solid to liquid states. This is achieved by integrating the mass equation, leading to changes in the apparent diameter of the EPCM domain while maintaining a constant diameter of the spheres or tubes. For the proper implementation of the model, it is validated against experimental data for both spheres and tubes [3], although the filler material for those systems is a packed bed. This study is innovative in its aspiration to integrate an existing technology (EPCM) into a novel thermal energy storage system (structured thermocline).