Within various solar power generation technologies Photovoltaic ("PV") attracts considerable attention due to its potential of contributing a major share of renewable energy in coming decades. The most appreciated advantage of this hi-tech innovative technology is its free, abundant and inexhaustible source of energy. There is more than enough solar radiation available all over the world to satisfy a vastly increased demand for solar power systems. The sunlight which reaches the Earth's surface is enough to provide 2,850 times as much energy as we can currently use. On a global average, each square meter of land is exposed to enough sunlight to produce 1,700 kWh of power every year. The average irradiation in Europe is about 1,000 kWh per square meter compared with 1,800 kWh in the Middle East. With projected CAGR of 40% - 50%, solar will still only constitute 1% of global installed capacity and 7.2% of new capacity by 2011.
PV technology involves the generation of electricity from light. The basis of this process is the use of a semiconductor material which can be adapted to release electrons, the negatively charged particles that form the basis of electricity. The most common semiconductor material used in photovoltaic cells is silicon, an element most commonly found in sand. All PV cells have at least two layers of such semiconductors, one positively charged and one negatively charged. When light shines on the semiconductor, the electric field across the junction between these two layers causes electricity to flow. The greater the intensity of the light, the greater the flow of electricity is. A photovoltaic system does not therefore need bright sunlight in order to operate, and can generate electricity even on cloudy days. "Classical" solar cells based on single crystals are achieving today up to about 24% solar efficiency in the lab, about 20% in modules at a very high price, and 13% at average prices. Skeiron uses the latest technology, high efficiency panels reaching up to 20% efficiency. Today scientists are working on reducing the production price and future use of nanostructures, optical conversion materials, etc., in order to overcome the thermodynamic limit of single band gap photovoltaic of about 30%.
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