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Photovoltaics, or PV for short, is a technology that converts light directly into electricity. Photovoltaics is also the field of study relating to this technology and there are many research institutes devoted to work on photovoltaics. Due to the growing need for solar energy, the manufacture of solar cells and solar photovoltaic array has expanded dramatically in recent years.

Photovoltaic production has been doubling every two years, increasing by an average of 48 percent each year since 2002, making it the world’s fastest-growing energy technology. At the end of 2007, according to preliminary data, cumulative global production was 12,400 megawatts.  

Roughly 90% of this generating capacity consists of grid-tied electrical systems. Such installations may be ground-mounted (and sometimes integrated with farming and grazing) or building integrated. Financial incentives, such as preferential feed-in tariffs for solar-generated electricity and net metering, have supported solar PV installations in many countries including Germany, Japan, and the United States.

Solar photovoltaics provided 0.04% of the world's Total Primary Energy Supply (TPES) for the year 2004, at a rate of growth to reach 0.40% by 2010. Photovoltaic cells produce electricity directly from sunlightAverage solar irradiance, watts per square metre. Note that this is for a horizontal surface, whereas solar panels are normally propped up at an angle and receive more energy per unit area.

Photovoltaics is best known as a method for generating solar power by using solar cells packaged in photovoltaic modules, often electrically connected in multiples as solar photovoltaic arrays to convert energy from the sun into electricity.

To explain the photovoltaic solar panel more simply, photons from sunlight knock electrons into a higher state of energy, creating electricity.Photovoltaics can refer to the field of study relating to this technology, and the term photovoltaic denotes the unbiased operating mode of a photodiode in which current through the device is entirely due to the transduced light energy.

Virtually all photovoltaic devices are some type of photodiode.Solar cells produce direct current electricity from light, which can be used to power equipment or to recharge a battery. The first practical application of photovoltaics was to power orbiting satellites and other spacecraft and pocket calculators, but today the majority of photovoltaic modules are used for grid connected power generation.

In this case an inverter is required to convert the DC to AC. There is a smaller market for off grid power for remote dwellings, roadside emergency telephones, remote sensing, and cathodic protection of pipelines.Cells require protection from the environment and are packaged usually behind a glass sheet. When more power is required than a single cell can deliver, cells are electrically connected together to form photovoltaic modules, or solar panels.

A single module is enough to power an emergency telephone, but for a house or a power plant the modules must be arranged in arrays. Although the selling price of modules is still too high to compete with grid electricity in most places, significant financial incentives in Japan and then Germany triggered a huge growth in demand, followed quickly by production.

Although module prices rose and plateaued, it is expected that costs and prices will fall to 'grid parity' in many places around 2010.Many corporations and institutions are currently developing ways to increase the practicality of solar power. While private companies conduct much of the research and development on solar energy, colleges and universities and institutes also work on solar-powered devices. Most research is being carried out in Germany, Japan, USA and Australia.

Solar power has received less research funding than other sources, but is seen as the most likely largest source of electricity in 15 years in the United States. The most important issue with solar panels is capital cost (installation and materials). Because of much increased demand, the price of silicon has risen and shortages occurred in 2005 and 2006.

Newer alternatives to standard crystalline silicon modules including casting wafers instead of sawing , thin film (CdTe, CIGS, amorphous Si, microcrystalline Si), concentrator modules, 'Sliver' cells, and continuous printing processes. Due to economies of scale solar panels get less costly as people use and buy more — as manufacturers increase production to meet demand, the cost and price is expected to drop in the years to come.

As of early 2006, the average cost per installed watt for a residential sized system was about USD 6.50 to USD 7.50, including panels, inverters, mounts, and electrical items. In 2007 investors began offering free solar panel installation in return for a 25 year contract to purchase electricity at a fixed price, normally set at or below current electric rates.A new photovoltaic "thin film" technology being pioneered by Californian company Nanosolar allows cells to be mass produced by printing them on to aluminium film at a fraction of the cost of existing techniques.

At December 2007 the company claims it can achieve costs of USD $0.99 a watt which would be comparable to coal produced electricity. Commercial production of roll-to-roll thin film technology, commenced on 2007 in Cardiff Wales, by a company called "G24 Innovations", owned in part by the Ecole Polytechnique Fédérale de Lausanne (EPFL), which is the source for some of its technology (Dye-sensitized solar cells).

It claims that its products "...incorporate raw materials that are both inexpensive and effectively limitless..." and that it has a current production capability of 30MW.A less common form of the technologies is thermophotovoltaics, in which the thermal radiation from some hot body other than the sun is utilized. Photovoltaic devices are also used to produce electricity in optical wireless power transmission

 
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