Why Solar Panels Work

Why Solar Panels Work

The following is our best modern understanding of why solar panels work. The complicated explanation will be explained in depth so that any reader can understand the concepts behind solar power.

The extrinsic semiconductor material is silicon doped with phosphorus and boron. Silicon is also a photoconductor. Silicon becomes heated as it absorbs infrared radiation, visible light, and some ultraviolet radiation. As it becomes heated, its electrons become energised. Further, due to the photovoltaic effect, photons, or sunshine cause electrons to jump from their place. This leaves an electron hole. When the electrons find a new hole or the same hole to rest in, they produce electricity. The electricity conducts efficiently due to the p-n junction created during the doping process. We capture the electrons’ resting states as direct current (DC) electricity.

It may sound complicated, but we can simplify it.

Intrinsic vs Extrinsic Semiconductors

A semiconductor is a material that acts as both a conductor and an insulator.

A conductor is an element like bronze which is a metal. It can be used in a form such as a wire to create a path for electricity to flow. 

An insulator is a material like glass, which does not create a path for electricity to flow. It can absorb heat.

A semiconductor only conducts electricity while heated.

An intrinsic semiconductor material is a semiconductor material without impurities. An intrinsic semiconductor has low conductivity.

An extrinsic semiconductor material is a semiconductor material with added impurities. An extrinsic semiconductor material is highly conductive.

Doping

The process of adding impurities to the intrinsic semiconductor material is known as doping.

A material like silicon is a semiconductor. It has four valence electrons. This means, there are four electrons on each silicon atom’s outermost shell.

The easiest way to picture the shells of an atom is to think about Saturn’s rings. The valence shell is much like the outermost circle around the planet. The atom is the planet in this analogy.

Pentavalent atoms are atoms with five valence electrons. For example, phosphorus. The extra valence electron becomes a free electron. 

A free electron is simply an electron which is free to roam.

Trivalent atoms are atoms with three valence electrons. For example, boron. The missing electron creates a hole which can be filled by free electrons.

Adding more pentavalent impurities to an intrinsic semiconductor material increases the number of electrons, making it negatively charged.

Adding more trivalent impurities to an intrinsic semiconductor material increases the number of electron holes, making it positively charged.

Adding to one side pentavalent impurities and to the other side trivalent impurities a p-n (positive-negative) junction is created.

This p-n junction creates a path for direct current (DC) electricity to flow.

Photovoltaic effect

Electricity is electrons flowing in a circuit. Electrons surround silicon atoms in a solar PV cell. Sunlight shining on the cells causes the electrons to eject from their positions. This leaves behind an electron hole. When a different electron finds this hole and combines with it, energy is created. The electron moves and we capture this as electricity.

This phenomenon is called the PV effect. PV stands for photovoltaic.

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