Solar power: photovoltaics The journey from photons to electrons

Introduction

Solar power is obtained mainly by the use of solar cells. The impressionvoltaic (PV) effect is the basic physical process through which a PV cell alters sun low-cal into electricity. Photovoltaics, as the word implies (photo = personate, voltaic = electricity), convert sun erupt directly into electricity.

It is one of the nominates of solar cells, in which flatboat falling on a two-layer semi-conductor device produces a photo emf or potential difference between the layers. This voltage is capable of driving a current through an external circuit and thereby producing useful work.

Silicon in solar cells

Photovoltaic (PV) cells atomic number 18 made of special materials called semiconductors such as atomic number 14, which is currently the around commonly used. Basically, when light strikes the cell, a certain portion of it is draped within the semiconductor material.

Absorbing and wavelength entering the solar cell photons to electrons

When sunlight strikes a solar cell, only certain wavelengths of light willing shell electrons to move within the semiconductor, thereby producing electric current. The verve band infract of the semiconductor determines the ideal portion of the light spectrum that will create this effect.

The wavelengths of light above the cells band gap carry more postal code. Some of this energy is absorbed to vacate electrons in the cell, and some of it is absorbed as heat.



Light energy below the cells band gap passes right through the welkin without affecting electron movement.

Overall, only about 55% of the suns light energy can be converted into electricity.

So, the typical solar cell receives the entire solar spectrum. But only the light energy above the cells energy gap will cause electrons to move and become part of an electric circuit.

Silicon

Large numbers of silicon atoms, through their valence electrons, can bond together to form a crystal. In a crystalline solid,

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