An Experimental Method to Directly Obtain a Photogenerated Current at   Each Junction within the Triple Junction Solar Cell
  In this paper we will report an experimental approach for directly determining the photogenerated current at individual junctions within the triple junction solar cell. The method is based on the measurement of different current-voltage curves; one with the usual illumination system, normally AM0 or AM1.5G, and the other curves with a light source, having a different spectral emission. The fitting of all current-voltage curves simultaneously, not individually, permit us to determine the photogenerated current of three junctions. It is necessary to have three characteristics or more. An example, with experimental current-voltage data points, is shown in this work. The main advantage of this new technique is its simplicity and its easy implementation at any laboratory with an electrical characterization solar cell system and a solar simulator. The method has been tested over a large quantity of TJ solar cells. 
Nelson Veissid, Ricardo Augusto Santos de Abreu