Phase change materials can be considered as innovative heat transfer media that allow to accumulate energy for a charge period and to produce energy for a discharge period. Such materials are widely used in building elements, electronic cabinets and other technical systems. At the same time, the heat conductivity of known phase change materials are very low and for an intensification of heat transfer it is possible to include in the considered systems the porous structure or solid matrix. The present research deals with numerical analysis of charging period of phase change material in a square cavity filled with phase change materials and heated from the bottom wall. For an augmentation of energy transport the vertical heat-conducting partitions are added to this cavity. Using the enthalpy porosity model, numerical analysis has been performed for different numbers of vertical partitions illustrating also the evolution of the charging period. It has been shown that a rise of the vertical partitions number results in reduction of charging period with suppression of convective energy transport mode. Moreover, evolution of phase change material melting reflects a strengthening of this process due to heat conduction enhancement with high volume of solid partitions of high thermal conductivity.