Defects in Solar Cells and Devices


Shunts in Crystalline Silicon on Glass (CSG) modules

O. Breitenstein, H. Straube


Within our cooperation with CSG Solar (Thalheim) we are investigating power loss mechanisms in CSG modules. Here the interpretation of lock-in thermograms is more complicated than for single solar cells, since the biases in the series-interconnected cells are floating. Therefore, in addition to lock-in thermography (see figure), we are using 2-D potential mapping to investigate the effect of a shunt on the whole module. Close-up thermograms of a cell in a CSG module (see figure) show a detailed structure that allows conclusions about area currents, edge shunting due to laser cutting, and thermoelectric heat transport (Peltier effect) from the contact holes to the p-n junction. We are also studying the basic heat conduction properties of thin film cells on glass and plastic substrate in lock-in thermography, as for these the expressions for standard cells are no longer valid.

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