Assessment of the illumination dependency of Al2O3 and SiO2 rear-passivated p-type silicon solar cells

Abstract

This Letter discusses an important difference between positively charged SiO2 and negatively charged Al2O3 rear-passivated p-type Si solar cells: their illumination level dependency. For positively charged SiO2 rear-passivated p-type Si solar cells, a loss in short circuit current (JSC) and open circuit voltage (VOC) as a function of illumination level is mainly caused by parasitic shunting and a decrease in surface recombination, respectively. Hence, the relative loss in cell conversion efficiency, JSC, and VOC as a function of the illumination level for SiO2 compared to Al2O3 rear-passivated p-type Si solar cells has been measured and discussed. Subsequently, an exponential decay fit of the loss in cell efficiency is applied in order to estimate the difference in the energy output for both cell types in three different territories: Belgium (EU), Seattle and Austin (US). The observed trends in the difference in energy output between both cells, as a function of time of the year and region, are as expected and discussed. ((c) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)