Grid-independent power supply for repeaters in mobile radio networks using photovoltaic/thermoelectric hybrid systems

At Fraunhofer ISE, a photovoltaic/thermoelectric hybrid system has been developed as a power supply for repeaters (e.g. mobile telephone repeaters) and integrated into a newly constructed repeater station. A modified thermoelectric generator from the Canadian Global Thermoelectric company has been used as the auxiliary generator. A microprocessor-controlled energy management system (EMS) allows fully automatic operation with minimal use of fossil fuels and appropriate battery operation management. As the auxiliary power supply can support the PV generator in supplying power to the load during periods with little sunlight, a very reliable power supply is achieved. Further, the dimensions of the PV generator and the battery capacity can be reduced without affecting the supply reliability. In Central Europe, for instance, the size of the PV generator can be reduced to a third of that needed for an exclusively PV system, if only 10% of the annual demand is met by the auxiliary generator. This allows a compact construction of the photovoltaic hybrid system and helps the numerous requirements on isolated telecommunications facilities to be fulfilled.