Solar cell, crystalline silicon high efficiency

Single-Crystal Silicon. Silicon is still the dominant material in photovoltaic. It has good efficiency, which is 25% in theory and 15% in actual practice. Silicon photovoltaic devices are made from wafers sliced from single crystal silicon ingots, produced in part by CVD (see Ch. 8, Sec. 5.1). However, silicon wafers are still costly, their size is limited, and they cannot be sliced to thicknesses less than 150 im. One crystalline silicon wafer yields only one solar cell, which has an output of only one watt. This means that such cells will always be expensive and can only be used where their high efficiency is essential and cost is not a major factor such as in a spacecraft applications. 

The influence of interface area on Voc is utilized in high efficiency crystalline silicon solar cells with the so-called point contact concept to increase the open circuit voltage by suppressing area related recombination [149], Recently, the point contact concept has been applied also in pc-Si H solar cells using photolithography or self-organized zinc oxide etch masks [150], However, so far Voc improvement could not be demonstrated. For more details of preparation and application of ZnO etch masks the reader is referred to the original work [118]. 

Progress in state-of-the-art solar cell processing has allowed the use of highly defected crystalline silicon wafers in industrial type solar cell production without a major reduction in cell efficiency. One prerequisite for obtaining... 

Among the various materials, silicon, which accounts for more than 90% of solar cells today, is undoubtedly the key, especially if we consider a large-scale deployment. To accelerate the deployment of photovoltaic technology by development of high-efficiency crystalline silicon solar cells, the Institute for Materials Research (IMR), Tohoku University, organized a unique domestic workshop in 2004 and 2005 to discuss the approach from the view point of... 

Solar voltaic cells based on crystalline silicon have operated with a 30% efficiency for experimental cells and 15-20% for commercial units available in 2008, at a cost of around 15 cents/kWh, compared to 4-7 cents/kWh for fossil fuel-fired power plants and 6-9 cents for those fired by biomass. Costs of photovoltaic electricity have shown a continuous downward trend. Part of the high cost in the past has resulted from the fact that the silicon used in the cells must be cut as small wafers from silicon crystals for mounting on the cell surfaces. Significant advances in costs and technology are being made with thin-fllm photovoltaics, which use an amorphous silicon alloy. These cells are only about half as efficient as those made with crystalline silicon, but cost only about 25% as much. A newer approach to the design and construction of amorphous silicon film photovoltaic devices... 

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