At solar-cell manufacturer Würth Solar (Schwäbisch Hall, Germany), current production yield of modules using cadmium-indium-gallium-selenide (CIS) technology is 90% and rising. The company has produced the modules at its Marbach, Germany pilot installation since 2000. It has long collaborated with system integrator AIT Göhner (Stuttgart, Germany), and has recently implemented a data tracking system to enhance quality.
At solar-cell manufacturer Würth Solar (Schwäbisch Hall, Germany; www.wuerth-solar.de), current production yield of modules using cadmium-indium-gallium-selenide (CIS) technology is 90% and rising. The company has produced the modules at its Marbach, Germany pilot installation since 2000. It has long collaborated with system integrator AIT Göhner (Stuttgart, Germany; www.ait-vision.com), and has recently implemented a data tracking system to enhance quality.
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In producing CIS cells, the likelihood that a 120 × 60-cm module will have the desired output of approximately 80 W is not apparent until the end of the coating process. Therefore, quality data must be collected earlier in the process to determine the origin of defects. Each glass plate is assigned to an individual inspection station by means of Data Matrix code identification and quality data are recorded every third or fourth step of the production process.
The code is applied by laser engraving, which is difficult to read on glass because of the low contrast between the engraving and surrounding surface. After testing various vision systems, Würth Solar selected the In-Sight 5400 and 5100 ID readers from Cognex (Natick, MA, USA; www.cognex.com ), which proved able to detect barely visible codes and decode them at distances greater than 7 ft. The lasering is followed by 19 processing steps including the application of the base coating and subsequent laser structuring, which gives the plates their cellular shape.
A quality inspection is vital at this juncture, as the key production step immediately follows the washing of the plates. In this step, a CIS coating is applied to the plates. The company plans to install additional vision systems to increase production output from 600 to 1100 solar modules per day.
