Thursday, July 18, 2013

ISS Literature Review - Lim Yan Zheng

Solar panels are made using photovoltaic cells that converts light directly into electricity. A module is a group of cells connected electrically and packaged into a frame which is commonly know as a solar panel, which can then be grouped into larger solar arrays. Photovoltaic cells are made of special materials called semiconductors such as silicon, which is currently used most commonly.

Basically, when light strikes the cell, a portion of it is absorbed within the semiconductor material. This means that the energy of the absorbed light is transferred to the semiconductor. The energy loosens the electrons, allowing them to move freely.

PV cells also all have one or more electric field that acts to force electrons freed by light absorption to flow in a certain direction. This flow of electrons is a current, and by placing metal contacts on the top and bottom of the PV cell, we can draw that current off for external use, say, to power a calculator. This current, together with the cell's voltage, defines the power that the solar cell can produce.

Solar technologies are broadly characterized as either passive or active depending on the way they capture, convert and distribute sunlight. Active solar techniques use photovoltaic panels, pumps, and fans to convert sunlight into useful outputs. Passive solar techniques include selecting materials with favorable thermal properties, designing spaces that naturally circulate air, and referencing the position of a building to the Sun. Active solar technologies increase the supply of energy and are considered supply side technologies, while passive solar technologies reduce the need for alternate resources and are generally considered demand side technologies.

Sources: (2010, January 1) "About Solar Energy and Solar Power Systems." Retrieved July 13, 2013, from,

Toothman, Jessika, and Scott Aldous. (2000, April 1) "How Solar Cells Work"Retrieved July 13, 2013, from,

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