"solar cell"  

•  A solar cell made from a mono crystalline silicon wafer is shown above. 
•  A solar cell (also called a photo voltaic cell) is an electrical device that converts the energy of light directly into electricity by the photo voltaic effect.
• It is a form of photoelectric cell (in that its electrical characteristics—e.g. current, voltage, or resistance—vary when light is incident upon it) which, when exposed to light, can generate and support an electric current without being attached to any external voltage source, but do require an external load for power consumption.
•  Photo voltaic’s  is the field of technology and research related to the practical application of photo voltaic cells in producing electricity from light, though it is often used specifically to refer to the generation of electricity from sunlight.
•  Cells can be described as photo voltaic even when the light source is not necessarily sunlight (lamplight, artificial light, etc.). In such cases the cell is sometimes used as a photo detector (for example infrared detectors), detecting light or other electromagnetic radiation near the visible range, or measuring light intensity.
• The operation of a photo voltaic (PV) cell requires 3 basic attributes:
• 1.  The absorption of light,  generating  electron-hole pair.
• 2.  The separation of charge carriers of opposite types.
• 3.  The separate extraction of those carriers to an external circuit.