Improvement Efficiency of Solar Cells Using III-V Dual Junction: InGap/GaAs

Abstract

Renewable energy is a very minor percentage of energy consumed in the world. Fossil fuels still dominate despite their drawbacks (degradation of the environment). Renewable energy is not yet cost competitive with fossil fuels. The conversion of energy from renewable sources, especially for inexhaustible and clean energy sources (solar cells), must be efficient to be viable for large scale use. Single junction cells (SJC) have a theoretical efficiency limit of 33.7%, called Shockley-Queisser limit (SQ). Because the cost of electricity produced from solar cells depends on their efficiency, improving their conversion efficiency is a key way to make them cost-competitive. The two most important efficiency losses in SJC are the inability to convert photons with energies below the band gap energy (Eg) into electricity and the thermalization of photon energies exceeding Eg. Dual Junction Solar Cells (DJSC) was proposed to avoid the efficiency losses and to overcome the SQ limit. Our simulation model, presented in a previous work, was used to calculate solar cells efficiency and to plot the current-voltage (I-V) characteristics and the power-voltage (P-V) characteristics curves. Our simulation results show that high conversion efficiencies can be achieved by DJSC, more than 43.5%.