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Title:
 
Loss Analysis and Efficiency Potentials for CIGS PV Modules without and with Metal Grid: Experimental Results Analyzed by Simulation
 
Author(s):
 
R. Wächter, G. Kaune, T. Repmann, K. Orgassa
 
Topic:
 
Photovoltaic Modules and BoS Components
Subtopic: PV Module Design, Manufacture, Performance and Reliability
Event: 37th European Photovoltaic Solar Energy Conference and Exhibition
Session: 4BO.14.6
ISBN: 3-936338-73-6
 
Price:
 
 
0,00 EUR
 
Document(s): presentation
 

Abstract/Summary:


The transparent conductive oxide (TCO) front contact of a CIGS thin-film PV module is commonly the main source of series resistance in the module, causing ohmic losses and limiting the cell width. Applying an additional metal grid on top of the front contact is becoming an established way to reduce these losses and at the same time permit using wider cells. However, a grid also introduces new losses and affects several other loss mechanisms in the module. To get the most from a metal grid, it is therefore essential to understand the changes in individual loss mechanisms and their relation to the grid and module properties. The present work analyzes the different losses in CIGS PV modules without and with metal grid. A PVMOS cell simulation using parameters determined from measurement results of such modules forms the basis for the quantification of individual electric loss components, while optical losses are determined from transmission/reflection measurements of individual layers. It is shown that the effective loss from grid shadowing is overcompensated by reduced overall electric losses and the higher short-circuit current resulting from a thinner and less conductive TCO layer. The wider cells and consequently reduced number of inactive cell interconnects also form a significant contribution to the higher efficiency of modules with metal grid. Grid modules have successfully been introduced into production at NICE Solar Energy and demonstrated an increase in module power of about 6%, in good agreement with the calculations presented here.