The present work aims to investigate a honeycomb system with PCM for solar energy applications. The solution is to combine the qualities of PCM and the honeycomb structure, in fact it spreads out the heat all over the PCM improving the effective thermal conductivity of the system. Transient regime numerical simulations are created for different pores per unit of length (PPU). The Solid-liquid PCM is paraffin wax. A numerical model with honeycomb structure is compared with a porous medium model. The porous medium is modelled with the extended Darcy-Brinkman law and to evaluate the heat exchange between the solid and the fluid zones a Local-Thermal Equilibrium assumption is used. By the results of the direct honeycomb model the characteristics such as permeability, inertial resistant coefficient, effective thermal conductivity and interfacial heat transfer are evaluated and then compared with the porous medium model. Numerical simulations were carried out using the Ansys-Fluent code. Results in terms of melting time, temperature fields, and stored energy as function of time are presented.