The advantages and limitations of photovoltaic solar modules for energy generation are reviewed with their operation principles and physical efficiency limits. Although the main materials currently used or investigated and the associated fabrication technologies are individually described, emphasis is on silicon-based solar cells. Wafer-based crystalline silicon solar modules dominate in terms of production, but amorphous silicon solar cells have the potential to undercut costs owing, for example, to the roll-to-roll production possibilities for modules. Recent developments suggest that thin-film crystalline silicon (especially microcrystalline silicon) is becoming a prime candidate for future photovoltaics.

To date the majority of investigations into the performance of amorphous silicon photovoltaic systems have been limited to single sites, and therefore the conclusions from such studies are unlikely to be as generic as they might at first appear. This paper compares data collected from different systems across the world in Brazil, Hong Kong, Spain, Switzerland, and the United Kingdom. All systems have been operating for a number of years, and are employing double junction amorphous silicon devices of a similar age manufactured by RWE Solar.The data are analysed for performance variations reflecting the different climatic zones, and the variations are explained on the basis of operating temperature, incident irradiation and seasonal spectral shift.

Abstract. Hydrogenated microcrystalline Silicon (µc-Si:H) produced by the VHF-GD (Very High Frequency Glow Discharge) process can be considered to be a new base material for thin-film crystalline silicon solar cells. The most striking feature of such cells, in contrast to conventional amorphous silicon technology, is their stability under lightsoaking. With respect to crystalline silicon technology, their most striking advantage is their low process temperature (220°C). The so called "micromorph" cell contains such a µc-Si:H based cell as bottom cell, whereas the top-cell consists of amorphous silicon. A stable efficiency of 10.7% (confirmed by ISE Freiburg) is reported in this paper.At present, all solar cell concepts based on thin-film crystalline silicon have a common problem to overcome: namely, too long manufacturing times. In order to help in solving this problem for the particular case of plasma-deposited µc-Si:H, results on combined argon /hydrogen dilution of the feedgas (silane) are presented. It is shown that rates as high as 9.4 Å/s can be obtained; furthermore, a first solar cell deposited with 8.7 Å/s resulted in an efficiency of 3.1%.

Abstract. Hydrogenated microcrystalline Silicon (µc-Si:H) produced by the VHF-GD (Very High Frequency Glow Discharge) process can be considered to be a new base material for thin-film crystalline silicon solar cells. The most striking feature of such cells, in contrast to conventional amorphous silicon technology, is their stability under lightsoaking. With respect to crystalline silicon technology, their most striking advantage is their low process temperature (220°C). The so called "micromorph" cell contains such a µc-Si:H based cell as bottom cell, whereas the top-cell consists of amorphous silicon. A stable efficiency of 10.7% (confirmed by ISE Freiburg) is reported in this paper.At present, all solar cell concepts based on thin-film crystalline silicon have a common problem to overcome: namely, too long manufacturing times. In order to help in solving this problem for the particular case of plasma-deposited µc-Si:H, results on combined argon /hydrogen dilution of the feedgas (silane) are presented. It is shown that rates as high as 9.4 Å/s can be obtained; furthermore, a first solar cell deposited with 8.7 Å/s resulted in an efficiency of 3.1%.

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