Photovoltaics
Renewable Energy Technologies
Photovoltaics are devices that convert light into electricity throught the photoelectric effect -- a quantum phenomenon in which an electron is ejected from an atom or group of atoms upon absorbing a photon. The most common type of photovoltaics are cells made from thin slices of bulk silicon ingots. However, photovoltaics have been created from a variety of semiconductor materials using a number of different manufacturing processes.
Efficiency
A photovoltaic's efficiency is the fraction of light energy falling on it that is converted to electricity, when it is connected to an electrical circuit. Since the flux of sunlight at sea-level on a clear day is approximately 1000 watts per square meter, the efficiency of a photovoltaic panel can be measured, roughly, by orienting it perpendicular to the rays of the mid-day sun and dividing the output power, in watts, by one thousand times the area of the panel, in square meters.
Currently-available photovoltaics range in efficiency from a few percent to just over fourty percent. 1
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