Thermal Management of GaAs and Si Solar Cells for Laser Power-Beaming Applications in Space and Earth Orbits

This investigation aims to develop mini solar arrays comprising commercially available 1 cm 2 silicon vertical multijunction (VMJ) and space-rated GaAs solar cells for incorporation into small modular satellites for laser power-beaming applications in space exploration and Earth orbits. The performance of the photovoltaic (PV) cells is investigated using different laser wavelengths and power densities to identify optimal operational conditions to maximise power generation and minimize thermal load. GaAs thin film solar cells are preferred for space applications due to reduced thickness and weight compared to Si counterpart. Initial device simulations reveal the maximum output power density for the Si VMJ and GaAs devices is achieved at wavelengths of ca. 850 and 725 nm, respectively. However, due to charge carrier thermalisation at these laser wavelengths, significant heat is generated within the solar cells leading to an increase in device temperature of ca. 170 K and 70 K for Si VMJ and GaAs, respectively, under 1 kW/cm 2 input power and ambient conditions. A number of passive and active cooling techniques, such as heat pipes, metamaterials and thermoelectric, are studied to generate further power output and harness the excess heat.