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The Very High Efficiency Solar Cell (VHESC) program is developing integrated optical system–PV modules for portable applications that operate at greater than 50% efficiency. We are integrating the optical design with the solar cell design, and have entered previously unoccupied design space. Our approach is driven by proven quantitative models for the solar cell design, the optical design, and the integration of these designs. Optical systems efficiency with an optical efficiency of 93% and solar cell device results under ideal dichroic splitting optics summing to 42·7 ± 2·5% are described. Copyright © 2008 John Wiley & Sons, Ltd.

Amorphous silicon based solar cells were deposited by dc plasma decomposition of silane and hydrogen. As the deposition rate increases, the processing time decreases and becomes comparable to the time required to heat the glass superstrate to the deposition temperature. This allows de-coupling of the temperature of the growing film that determines the hydrogen out-diffusion processes from that of the gas, which influences the formation of multiple silicon containing molecules that increase the light induced degradation of the material. Consequently, reducing the initial temperature of the superstrate is shown to maximize the initial performance while maintaining the stability obtained at higher deposition chamber temperatures.

Since the fabrication of the first amorphous silicon solar cell in 1974 and the introduction of the first commercial products in 1980, shipments of amorphous silicon solar cells have grown to about 40 MW in 2001. The majority of these products have been fabricated on tin oxide coated glass in a monolithic series-connected configuration. In the current paper, the author describes the manufacturing process used to fabricate amorphous silicon monolithic series connected PV modules and also reviews the performance, reliability and stability of the modules. Issues such as manufacturing costs and environmental impacts are also discussed. Further research, development and engineering are required to assure that a-Si photovoltaics will play a major role in future world energy production.

Electrochemical corrosion effects can occur in thin-film photovoltaic (PV) modules that are fabricated on tin-oxide-coated glass when operating at high voltages and at elevated temperatures in a humid climate. The current study shows that this corrosion is associated with a delamination of the tin oxide layer from the glass, which is caused by sodium accumulation near the interface between the tin oxide and the glass and by the ingression of moisture into the PV module from the edges. This corrosion in thin-film PV modules can be significantly reduced by altering the growth conditions of the tin oxide or by using zinc oxide as a transparent conductive oxide electrode. Copyright © 2003 John Wiley & Sons, Ltd.

The growth rate of a-Si increases with dc plasma current with a single slope at high flow rates but with a reduced slope above a certain power for lower flow rates when using a showerhead type gas delivery system. This is in contrast to saturation of the growth rate under gas depletion conditions previously reported. The change to a smaller slope for lower flow rates at higher powers can be understood in terms of a transition to reactive radical dominated growth. We show that a-Si single junction cell performance deteriorates under gas depletion conditions.

The status of a-Si solar cell technology is reviewed. This review includes a discussion of the types of solar cell structure that are being used in commercial products. An overview of the development efforts under way involving new materials, such as alloys and microcrystalline films, and their impact on device performance is given. The status of stability in a-Si solar cells and projections for costs for large-scale manufacturing facilities are reviewed. The development of markets for a-Si photovoltaics is also discussed. >