Roll-to-roll manufacturing of amorphous silicon alloy solar cells with in situ cell performance diagnostics

In order to meet the price target necessary for widespread use of solar cell products, Energy Conversion Devices, Inc., ECD, has developed and commercialized a continuous roll-to-roll manufacturing technology for the production of a-Si alloy solar cells. Since the early 1980s, we have advanced this technology from a small-scale pilot machine to a large-scale production machine. In 2002, ECD commissioned a 30 MW per year machine for United Solar Systems Corp. in Auburn Hills, Michigan. The RF PECVD a-Si alloy solar cell processor, designed and built by ECD, deposits triple-junction solar cell materials consisting of nine layers of a-Si alloys in a continuous roll-to-roll operation simultaneously on six coils of 130 μm thick, 0.36 m wide, 2.6 km long stainless-steel substrate at 1 cm/s. In order to minimize production losses due to undetected deviations of production conditions and carry on a continuous program of device optimization, we have developed and are incorporating in situ cell performance diagnostic systems.