Investigation on the Angle and Spectral Dependence of the Internal and the External Quantum Efficiency of Crystalline Silicon Solar Cells and Modules

To improve energy yield predictions and to fully understand the physical behavior of solar cells, it is necessary to investigate the effects caused by a change in the angle of incidence. All relevant angle-dependent effects are presented in this paper and angular correction factors are introduced. A new analytical model is presented, which includes internal reflection, free carrier absorption, and other parasitic absorption processes. The angular effects were exemplarily studied for the case of a very simple planar solar cell sample and a standard module sample. With an effective angle approach, the variation of the internal quantum efficiency in the standard solar module could be emulated and the results were verified with the help of a ray tracing tool developed for this purpose. The influence of the different angular factors on the current density of a standard module at an incidence angle of 70° is finally presented.