What is Photovoltaic?

Photovoltaics refers to the direct conversion of solar energy into electric energy using solar cells made of silicon. This probably the most environmentally-friendly way of generating electricity. Photovoltaics is considered a renewable form of energy.

Convert the sunlight into electricity

Photovoltaic cells convert the sunlight into electricity. A typical example of a device powered by photovoltaic cells is a solar powered calculator. This type of device only needs a small amount of electrical power to work and can even be used in a room with artificial light (bulbs / fluorescent light).

The term photovoltaics is made up of the Greek word “photos” for light and the last name of Italian physicist Alessandro Volta. Each energy module consists of crystalline silicon cells. The targeted doping of the silicon produces different charge layers. The so-called “photovoltaic effect” is created when sunlight hits the solar cells. This builds up direct voltage that is discharged as a direct current. Depending on the application, the direct current can either be used immediately or converted into alternating current, or it can also be fed into the public grid.

Sunlight detaches electrons

In a photovoltaic cell, sunlight detaches electrons from their host silicon atoms. Tiny packets of light energy called photons are captured by electrons, and impart enough energy to kick the electron free of its host atom. Near the upper surface of the cell is a “one-way membrane” called a PN-junction. The PN-junction is formed by diffusing tiny quantities of phosphorus to a depth of about one micrometer into a thin wafer of silicon.

When a free electron crosses the PN-junction it cannot easily return, causing a negative voltage to appear on the surface facing the sun (and a positive voltage on the rear surface). The front and rear surfaces can be connected together via an external circuit in order to extract current, voltage and power from the solar cell.

 

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