The purpose of this study is to develop and justify the parameters of new structures of seasonal batteries with phase transformation of the storage material, which allow to get rid of deformations and destruction of the contacting elements of the battery structure when the aggregate state changes. The design of a seasonal battery with a phase transformation of the storage material is based on a shell that allows to compensate for the expansion of the material when the aggregate state changes. Determination of the dependence of the energy parameters on the geometric parameters and thermophysical parameters of the constituent elements of the seasonal battery with phase transformation, which allow the battery capacity and power at different stages of discharge and charge. The study of phase transition processes made it possible to establish the characteristic stages of charging and discharging the battery: heating the material to the phase transformation temperature; heat transfer for phase transformation 0°C; heating the material after the phase transformation; cooling the material to the phase transformation temperature; heat removal for phase transformation 0°C (in some cases hypothermia up to 3-4°C is possible; cooling of the material after the phase transformation. The largest battery power values occur at the stage of cooling the material to the temperature of the phase transformation and heating the material after the phase transformation (25.62 kW ). The lowest power of the battery (13.56 kW) is observed heating of the material to the temperature of the phase transformation and cooling of the material after the phase transformation, which is explained by the low heat exchange of the accumulating substance in the solid state. Based on the conducted research, recommendations were made that the prospects for the development and optimization of the design of seasonal batteries with the phase transformation of the accumulating material.