Green Energy – How Solar Panel Works

2 Apr

Solar Cell

Photovoltaic’s is the direct conversion of light into electricity at the atomic level. Some materials exhibit a property known as the Photoelectric Effect that causes them to absorb Photons of Light and release electrons. When these free electrons are captured, an Electric Current results, that can be used as electricity.

The Photoelectric Effect was first noted by a French physicist, Edmund Becquerel, in 1839,

Solar Panel

who found that certain materials would produce small amounts of electric current when exposed to light. In 1905, Albert Einstein described the nature of light and the Photoelectric Effect on which Photovoltaic Technology is based, for which he later won a Nobel Prize in physics. Solar cells are made of the same kinds of semiconductor materials, such as Silicon, used in the microelectronics industry.

Solar Array

For solar cells, a thin Semiconductor Wafer is specially treated to form an electric field, positive on one side and negative on the other. When light energy strikes the solar cell, electrons are knocked loose from the atoms in the semiconductor material. If electrical conductors are attached to the positive and negative sides, forming an electrical circuit, the electrons can be captured in the form of an electric current (electricity). This electricity can then be used to power a load, such as a light or a tool.

A number of solar cells electrically connected to each other and mounted in a support structure or frame is called a photovoltaic module. Modules are designed to supply electricity at a certain voltage, such as a common 12 volts system. Multiple Modules can be wired together to form an Array. Photovoltaic Modules and Arrays produce Direct-Current (DC)electricity. They can be connected in both series and parallel electrical arrangements to produce any required voltage and current combination.

Mechanism of Solar Cell

In a Single-Junction PV Cell, only photons whose energy is equal to or greater than the band gap of the cell material can free an electron for an electric circuit. In other words, the photovoltaic response of Single-Junction Cells is limited to the portion of the Sun’s Spectrum whose energy is above the band gap of the absorbing material, and Lower-Energy Photons are not used. A Multijunction Device is a stack of individual Single-Junction Cells in descending order of band gap. The top cell captures the High-Energy Photons and passes the rest of the Photons on to be absorbed by Lower-Band-Gap Cells.

Much of today’s research in Multijunction Cells focuses on gallium arsenide as one (or all) of the component cells. Such cells have reached efficiencies of around 35% under concentrated sunlight. Other materials studied for Multijunction Devices have been amorphous silicon and copper indium diselenide.

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One Response to “Green Energy – How Solar Panel Works”

  1. Janet August 1, 2013 at 8:26 pm #

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