Abstract: A photovoltaic cell (Ci) comprising at least one sub-cell of a first semiconductor (1) and a sub-cell of a second semiconductor (2) connected by means of three electrodes (T1, T2, T3). The second semiconductor is typically silicon, while the first semiconductor is a material with wider band-gap deposited closer to a surface of incidence of electromagnetic radiation. The first electrode (T1) is on the forward face of the photovoltaic cell (Ci), while the second electrode (T2) and the third electrode (T3) are on the rear face of said photovoltaic cell (Ci). Both the second electrode (T2) and the third electrode (T3) are connected to the second semiconductor (2). The regions on both sides of the area of contact between the first semiconductor and the second semiconductor have the same type of majority carriers. Thus, a photovoltaic cell (Ci) is achieved with a high conversion efficiency that is capable of being integrated into devices with two terminals.

Abstract: An energy storage system is provided. The energy storage system includes a vessel made of a refractory material and containing a phase change material, a thermally insulating cover at least partially surrounding the vessel, an emitter, made of a refractory material, having a first side arranged to be heated by the phase change material and a second side intended to radiate thermal power, at least one photovoltaic cell arranged to receive the thermal power emitted by the second side of the emitter, and electric means for heating the phase change material.