Detailed Current Loss Analysis for a PV Module Made With Textured Multicrystalline Silicon Wafer Solar Cells

Abstract

We present a top-down method to quantify optical losses due to encapsulation of textured multicrystalline silicon wafer solar cells in a photovoltaic module. The approach is based on a combination of measurements and mathematical procedures. Seven different loss mechanisms are considered: 1) reflection at the glass front surface, 2) reflection at the metal fingers, 3) reflection at the textured solar cell surface, 4) absorption in the antireflection coating, 5) absorption in the glass pane and the encapsulation layer, 6) front surface escape, and 7) losses due to a non-perfect solar cell internal quantum efficiency. Losses for each of these mechanisms are obtained as a function of wavelength, and the corresponding current loss for each loss mechanism is calculated. Comparing simulated and measured results, the method predicts the module quantum efficiency with an error of less than 2% and the collected current with an error of less than 1%. In the presented example, the biggest loss (7.4 mA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) is due to the nonperfect quantum efficiency, followed by reflection losses at the glass front (2.2 mA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) and absorption in the glass and encapsulation layer (1.1 mA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ).