What is the current market for solar-cell/photovoltaic (PV) manufacturing sector?

The combined PV equipment and materials sector generated $3.7 billion in 2006, with the polysilicon-driven materials side accounting for most of the total, according to SEMI. By 2010, the association forecasts the overall market will top $10 billion, with thin-film tools grabbing an increasing share of the pie.


How long will a system last?

The average lifetime of a PV module can be in excess of 20 years, crystalline silicon modules in particular have a very long life span. In addition, they require very little maintenance. Other system components will have a varied lifespan, for example batteries in stand-alone systems can last between 2 and 15 years depending on type.


What applications are there for PV?

PV technology has many applications, both for stand-alone systems and for integration onto buildings. PV may be used in applications such as monitoring stations, radio repeater stations, telephone kiosks and street lighting to name just a few examples. There is also a substantial market for PV technology in the leisure industry, with battery chargers for boats and caravans, as well as for powering garden equipment such as solar fountains.

In more recent years, PV has become more widely used in urban areas, where it can be integrated into new buildings or mounted onto existing buildings. This is a rapidly growing market. PV technology is ideally suited to the urban environment, providing pollution and noise free electricity without using extra space.

PV technology is also widely used in the developing world. The technology is particularly suited here, where electricity grids are unreliable or non-existent, with remote locations often making PV power supply the most economic option. In addition, many developing countries have a high level of solar radiation levels year round.


Does PV technology need bright sunshine to work properly?

The electrical output of a PV cell is dependent upon the intensity of the light to which it is exposed. So PV cells will tend to generate more electricity on bright days than when skies are overcast. However, photovoltaics do not need to be in direct sunlight to work, so even on overcast days a PV cell will be generating some electricity.


What types of materials are used in making a photovoltaic cell?

The most widely used material for PV cells is silicon, a semiconductor. The silicon is "doped" (that is, it has a certain amount of impurities placed into the silicon crystal) with either boron or phosphorus to give it the properties needed to be a PV cell and give up electrons when exposed to light. The photons of light (photons are actually small particles of light) "knock" the electrons out of the outside band of the silicon atom and that is what creates the PV effect.


What is thin film technology?

Another approach to producing solar cells that shows great promise are thin films. Commercial thin films today are principally made from amorphous silicon; however, copper indium diselenide and cadmium telluride also show promise as low-cost solar cells. Thin-film solar cells require very little material and can be easily manufactured on a large scale. Manufacturing lends itself to automation and the fabricated cells can be flexibly sized and incorporated into building components.


What is the history of PV technology?

In 1839, Edmond Becquerel noticed that, in addition to heat, the sunlight that is absorbed by certain materials can produce small quantities of electricity. This curious phenomenon was limited to measuring light levels in photography until the 1950s. Then, the combination of improved purification techniques for semiconductors, the advances in solid state devices beginning with the development of the transistor in 1947, and the needs of the emerging space program, led to the development of photovoltaic cells. In 1954, a 4% efficient silicon crystal photovoltaic cell was demonstrated. By 1958, a small silicon array was used to supply electrical power to a U.S. satellite.


What is photovoltaic (PV)?

PV is a basic type of solar electric technology. The photovoltaic (PV) process converts sunlight, the most abundant energy source on the planet directly into electricity. The equipment required for this process has no moving parts and as a result requires minimal maintenance. In addition, the electricity is generated with no emissions and no noise.

A PV cell consists of two or more thin layers of semiconducting material, most commonly silicon. When the cell is exposed to light, electrical charges are generated and this can be conducted away by metal contacts as direct current (DC).

The electrical output from a single cell is small, therefore multiple cells are connected together to provide a more useful output. Cells connected in this way are encapsulated (usually behind glass) to form a weatherproof module or panel.

Multiple modules can likewise be connected together in order to provide sufficient power for common electrical appliances.


What is an analog signal?

An analog or analogue signal is any variable signal continuous in both time and amplitude. It differs from a digital signal in that small fluctuations in the signal are meaningful.


What is an ASIC?

An application-specific integrated circuit (ASIC) is an integrated circuit (IC) customised for a particular use, rather than intended for general-purpose use. For example, a chip designed solely to run a cell phone is an ASIC. In contrast, the 7400 series and 4000 series integrated circuits are logic building blocks that can be wired together to perform many different applications. Intermediate between ASICs and standard products are application specific standard products (ASSPs).


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