AN OPTICAL MODEL FOR THE ABSORPTION FACTOR OF TEXTURED CRYSTALLINE SILICON PV CELLS

摘要

An optical model is developed to determine the fraction of irradiance absorbed in a typical encapsulated crystalline silicon PV cell. It is found that the active area of an untextured PV cell has an absorption factor of 85.6%, while for a textured cell this absorption factor is as high as 90.3%. It is pointed out that free-carriers, in particular those introduced by emitter doping, contribute significantly to the absorption of long-wavelength solar irradiance. It was investigated to which extent the absorption factor can be controlled by the doping levels in the cell. Using a more shallow emitter reduces the absorption factor by only 1%. For photovoltaic/thermal applications there is room for a 3% increase in absorption factor by absorbing more irradiance in the back contact.