Photovoltaic energy conversion electric power

Discovery of amorphous silicon and its dopability has already had a tremendous impact on industrial applications of amorphous materials. Amorphous Si is now used fairly extensively as a photovoltaic material. In photovoltaic applications, solar photons excite the electrons across the gap and the resulting electron-hole pairs, are driven towards the respective electrodes in order to prevent their recombination. Electron is driven through an external resistance to generate the electrical power. The efficiency of conversion of solar energy to electrical power is characterized by an efficiency factor, r, which is given by. 

Ideally, all photons with a wavelength of about 900 nm or shorter should be harvested and converted to electric current. This limit is derived from thermodynamic considerations showing that the conversion efficiency of any single-junction photovoltaic solar converter peaks at approximately 33% near the threshold energy of lAeV.1 2 There are numerous ways to convert the solar radiation directly into electrical power or chemical fuel. The silicon solar cell is the most efficient in this respect. Nevertheless, the capital cost of such devices is not attractive for large-scale applications. 

There are several approaches to the conversion of sunlight into electrical or chemical energy. The first method is the direct transformation into electricity by means of photovoltaic cells. These are based on a purely photophysical process, and they have been used successfully in many small-scale applications to provide electrical power for artificial satellites, for... 

The photovoltaic devices are the most modern. They are semi-conductor or. in other words, solid-state components, and they incorporate the principle of the conversion of radiant energy directly into usable electrical power. The photovoltaic phenomenon is founded upon the basic photoelectric equation of Albert Einstein, namely ... 

Due to the incorporation of VRLA products into such new applications as HEV and photovoltaics/wind/hydro-electric energy conversion, or RAPS (remote-area power sources), the development of cycling algorithms involving a relatively narrow SoC window has emerged. While it is beyond the scope of this review to cover this topic in great depth, a general overview will be presented. 

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