Simple Solar Cell Explanation

 The solar cell. 

 Solar cells use differing materials with three basic properties, a positive material (P-type),like boron or aluminum (known as group 13 elements in the periodic table),  and a negative material like phosphorus, arsenic, or antimony (you guessed it... the N-type), with silicon (insulator) in the middle.

pure silicon

The process for adding these materials together is considered doping, in a semiconductor like silicone. The material is added as the crystal is grown to be included in the lattice of the crystalline structure. Normally silicon crystals have a repeating pattern to their lattice structure which leaves no room for electrons to pass and makes it a good insulator. By doping the lattice structure is interrupted to attach either an element that has excess (in the case of a n-type element) or is lacking electrons in the valence shell of its atomic structure (p-type). (dig deep... I know 6th grade science was a long time ago) In case you don't remember the valence shell is the outermost layer of an atom.(don't feel too bad, I had to look it up again myself)

N-type silicon (Si) doped with arsenic (As)

  So the couch potato,(excess and just sort of hanging out) electrons in the n-type can be knocked loose by incoming photons to be caught by the p-type silicon holes (openings in the valence shell). So in this way electrons can be collected by taking advantage of the voltage difference in the two materials created by the sunlight (photons) passing into the doped silicon lattice structure.


 To form an electrical circuit for energy to flow you have to have a voltage difference, electricity flows downhill, higher to lower. The solar cell takes advantage of this by having a P-type, and N-type node separated by silicon to create a positive and negative side that you can attach conductors to, to collect the electricity produced by the action of the photons knocking the electrons out of their loose valence bonds (N-node) into the holes in valence level of the p-node side. 

 This is just very simple explanation of the basic operation of a solar cell, there are many other kinds of materials used for the construction process I have not listed here. Not to mention several ways to combine the principles I have listed here to produce different kinds of solar panels. With differing construction methods and materials, different bandwidths of light can be accessed to produce electricity in different lighting conditions. Or increase efficiency by combining different bandwidth producing elements into one panel to increase overall efficiency.  To date I have heard of panels containing up to three different "cells" in one panel to collect photons the prior "layer" was unreceptive to. But you wont likely be finding them at a yard sale any time soon!!