This paper describes the dynamic behaviour of a high temperature electrolysis system through a transient model. The system is based on solid oxide electrolysis cells (SOECs), coupled with a wind farm in a power-to-gas configuration. The model takes into account mass and energy balances for the SOEC stack as well as for the different balance of plant components. A 1D approach has been implemented to study the system behaviour along the flow direction. The model is able to capture the physical behaviour of the SOEC system under transient operation including shifts in thermal regimes (e.g. endothermic versus exothermic), consumption of reactants and hydrogen production. Dynamics of pressurized SOEC systems are reported. The model is used to evaluate the storage option of energy produced from a wind farm in Italy. The evaluation includes the incorporation of the model with daily curves of an Italian wind farm and power consumption of local users.