THE PRESENT STATE AND FUTURE-PROSPECTS OF HIGH-EFFICIENCY PHOTOVOLTAIC CELLS FOR SOLAR POWER-SYSTEMS

Solar power systems for industrialization of space and future other advanced missions must face tremendous challenges. This concerns mainly energy conversion efficiency and weight. Based on the utilization of GaAs and related III-V compound semiconductors, recent breakthroughs in the solar cell efficiency promote the photovoltaic option as a serious candidate. This paper reviews the present state of research in this field, showing a strong increasing effort in the action on high efficiency tandem cells. After a rapid description of the multispectral concept, mainly focused on the estimate of the achievable practical efficiency limit, recent published data are presented : In the case of GaAs-based tandem photovoltaic structures, efficiency values in the range of 30% have been obtained in space solar simulators, exhibiting a substantial improvement of the energy conversion performance under concentration. The utilization of photovoltaic concentrators in solar power systems is briefly discussed. Alternatively, a cost-competitive use of III-V multispectral cells in planar array modules is shown to be possible in the future. thanks to progress in the deposition of these materials on low cost light substrates.