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Solar
Photovoltaic Technologies
PVs are kind of like magic. They turn sunlight directly into electricity with no moving parts, no combustion, no noise, and no waste products. PV modules (also called panels) typically have a peak power output of 50 to 300 watts. Modules can be assembled into arrays, which can vary from just two modules for a small residential system to hundreds of modules for a utility-scale system of 100 kW or more. The remaining equipment and structure in an installed PV system, including necessary services is called the Balance of System. The Solar Electric Power Association provides fact sheets on Solar Arrays and Balance-of-System
There are a few technologies competing for space on the distributed generation PV market.
Crystalline silicon
Crystalline silicon modules are used in almost all commercial PV systems. In this design, silicon (which starts out as sand) is mixed with a small amount of a substance with a different number of electrons (such as boron or phosphorus). When light hits the PV material, electrons are dislodged. This movement of electrons creates an electric current. Crystalline silicon modules have reasonably high conversion efficiencies (typically 12 to 14 percent) and are made from readily available materials. Unfortunately, they are expensive to manufacture.
Crystalline silicon (C-si) modules were the first widely deployed PV technology, and remains the workhorse of the PV industry with about 80 percent of the PV cell market to date. As such, it benefits from comparatively well-developed production and distribution economies that other, emerging technologies do not yet have. And while C-si has a greater efficiency per square meter than the nearest competitor, these cells are expensive to produce. Crystalline silicon modules cost about $5 to 6/per watt. More
information on Crystalline Silicon from the National Center for Photovoltaics.
Amorphous silicon
Amorphous silicon modules, crystalline silicon's closest competitor in customer-sited systems (although it has less than 10 percent of PV cell market) has lower solar conversion efficiencies but use considerably less material and their manufacturing processes are well suited for mass production. Costs for thin-film are about the same per watt as crystalline silicon, but because of lower efficiencies, a greater number of these modules are required, increasing installation costs as well as requiring more space for their installation. More information on Amorphous
Silicon from NCPV.
Building integrated PV
Because of its size and flexibility, thin film can be used in building products, such as roofing tiles and awnings, called Building Integrated Photovoltaics. Functioning as a both construction element and power generator adds value to the PV as it brings down the costs of construction.
For more details about these technologies, see the Solarbuzz site, which also provides an
extensive list of international cell and
component manufacturers.
For more information on Building Integrated Photovoltaics see the Department of Energy's Solar
Buildings site.
The PV Resources website lists
the “Top 25
Building Integrated PV Systems” representing the world’s
biggest building integrated photovoltaic systems.
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