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Bitterfeld-Wolfen, Germany

Straube H.,Max Planck Institute of Microstructure Physics | Straube H.,Sovello AG | Wagner J.-M.,Max Planck Institute of Microstructure Physics | Wagner J.-M.,University of Kiel | And 3 more authors.
Journal of Applied Physics | Year: 2011

We describe the measurement and modeling of lock-in thermograms for three differently processed crystalline silicon on glass thin film silicon solar modules. For the purpose of defect impact evaluation, a bias series of lock-in thermograms for a single cell in each module is measured. The resulting images around maximum power point bias show pronounced Peltier heat redistribution inside the cell, which needs to be taken into account for quantitative evaluation of the thermography results. This is done using a finite differences electronics simulation of the current flow inside the module and convolution of the heat distribution patterns with the thermal blurring. The procedure makes it possible to extract relevant cell performance parameters like the area diode dark saturation current and nonlinear edge shunting current densities as well as to evaluate the relative impact of these on the efficiency under simulated illumination. © 2011 American Institute of Physics.

Reimann C.,Fraunhofer Institute for Integrated Systems and Device Technology | Muller G.,Fraunhofer Institute for Integrated Systems and Device Technology | Friedrich J.,Fraunhofer Institute for Integrated Systems and Device Technology | Lauer K.,CiS Research Institute for Micro Sensors and Photovoltaics | And 5 more authors.
Journal of Crystal Growth | Year: 2012

The String Ribbon technology provides multi-crystalline silicon wafers for low cost and high efficiency solar cells (16% efficiency on untextured cells). This paper deals with the systematic characterization of standard String Ribbon wafer material produced by the Sovello AG. The investigations of the grain structure, the dislocation density (EPD), the minority carrier lifetime τ and the interstitial iron content Fe i show a clear correlation between lifetime, EPD, and interstitial iron concentration. High lifetime areas consist mainly of Σ3 twinned grains with low EPD and low interstitial iron content in the range of 4×10 11 atoms/cm3. The dislocation and interstitial iron distribution is non-uniform over the ribbon width. © 2012 Elsevier B.V.

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