In many countries, a large part of the energy consumption in buildings is used for heating and increasingly also for cooling. New, sustainable solutions are urgently needed to address this problem. For this purpose, a prototype of a new heat storage and energy generation system for buildings was developed and investigated. In this energy pole both energy generation and energy storage are performed. Furthermore, the pole can be used for cooling. Energy is generated by heating a solar thermal absorber through incident solar radiation. The energy generated can be stored in tanks integrated in the pole. Energy is stored in two different units: one filled with water, the other with a phase change material. The experimental investigations focused on the suitability of the energy poles for the heating and cooling of buildings. Thermal simulations are of particular importance for the further development of the energy pole, as they enable predictions of the energy efficiency of different designs under varying boundary conditions as well as cost-efficient investigations of adjustments in the design. In this paper, experimental results and the modelling of the prototype in a thermal building simulation program are presented, focusing on the energy storage. The validation using measurement data from the prototype shows that even though the thermal behavior of phase change materials as well as the entirety of the physical processes in the energy pole are difficult to model correctly, a good representation was achieved.