Abstract Thermal energy storage can play an important role to reduce the mismatch between energy demand and supply. This work presents two cascading systems with the aim to increase energy density and storage efficiency. Furthermore, the influence of the system volume on the energy density is depicted compared to only including the volume of the storage material. Both cascading cycles indicate an increase in energy density and storage efficiency on a material level compared to a direct use. When considering also the auxiliary components of the system, the energy density can decrease under the value of the direct use system. Thus, it is very important to gaze at the whole system for the calculation of energy densities.