Solar panel development for high altitude and low earth orbit application

Abstract

Stable and reliable source of electrical energy is a requirement for efficient operation of satellites. Several sources of electrical power for satellites exist such as fuel cells, nuclear or battery stored Direct Current energy but of late concentration has been on solar cells as the advantages compared to the other sources are many. Solar cells are p-n semiconductor devices which convert light energy into electrical energy by photovoltaic effect. The biggest drawback of solar cell energy system is the low light to electricity conversion efficiency. Apart from powering satellites, solar cells and panels have found other numerous applications such as in water pumping systems, rural electrification, street lightning. Photovoltaic principle of solar cells started way back in 1839 when Alexandre Edmund Becquerel observed that electrical currents arose from certain light induced chemical reactions. A comprehensive understanding of this phenomenon became clear when the science of quantum theory was unveiled in the early parts of the 20th century. Most solar cells and panels available today in the market are silicon based made of single junction technology. The disadvantage with single junction technology is that the p-n junction is made of a single type of solar cell material which absorbs a fraction of light wavelengths from the spectrum of light. The disability of the single p-n junction to convert all the light energy to electricity accounts for the low efficiency for the solar cells. One way to go around the problem of efficiency is to use multi-junction solar cells. Multijunction solar cells are designed to absorb a large fraction of the light spectrum and convert them to electrical energy. They are made of multiple p-n junctions made of different solar cell materials which absorb different parts of light spectrum and convert them to electrical energy. In this thesis, a design of a multi-junction solar cell for developing space solar panel is presented. The multi-junction cell has been designed from simulation results of different solar cell materials simulated with space conditions. Ideas and recommendations for future work are also presented.