Solar modules cell width

Fig. 8.11. Monolithic series-connection of silicon thin film solar modules by a sequence of deposition and laser scribing steps. The current flow is indicated by the dotted arrow. For calculation of resistive and optical losses the active cell width ioa and dead area width Wd are needed...

The aperture area of a solar module is defined by the inner boundary of total laser scribed area. For every kind of series-connection, the active solar cell area is reduced by the area of the interconnection structure. Area losses increase if the cell width is reduced. On the other hand, electrical losses in contact layers become more severe with increasing cell width due to increasing cell current. Hence, optimization of the cell width must consider both area losses (dead area) due to patterning and series resistance losses due to TCO sheet resistance. These power losses can be described by the loss factors /, which is the sum of the loss factors /d (area losses) and /tco (resistive losses in front TCO) [69] ... 

Fig. 8.12. Calculated active area (gray) and aperture area efficiencies (black) of a-Si 11/jLif- Si 11 tandem solar modules as function of cell width for different TCO sheet resistance values Rtco 5 0 (dashed), 10O (solid), and 20 0 (dotted)...

For the production and upscaling of practical solar cells on large areas, modules have to be constructed from individual cells. The relatively high sheet resistance of the Sn02 F coating (usually about 10 Q/D), used as the current collector, limits the width of individual cells to less than 1 cm. 

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