| Atoms usually
have a certain number of electrons,
but sometimes, especially with unstable atoms, an atom will, for one reason
or another, give up one of it's electrons. This causes the atom to get
a slight positive charge as a whole, because usually the charge of the
protons
mostly cancels out the charge of the electrons. With some atoms it's even
possible to get the atom to give up ALL of it's electrons, making it an
ion.
When an atom is missing it's usual amount of electrons, it can rip electrons away from other atoms in order to make itself more balanced. Electrons have certain spaces built-in for them in an atom. When an electron breaks away from the atom, the 'hole' is still there, and will attract any free electrons around in order to fill it. |
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| The words 'n-layer' and 'p-layer' are abbreviations signifying which
layer has a negative electrical charge, and which has a positive one.
Sometimes, under certain conditions, you can get a normal atom to break off and give up some or all of it's electrons. The atom becomes unbalanced, and if you can catch those electrons and flow them through a circuit before the atoms reclaim them, then you've got a power source. The trick is to keep the reaction going. Batteries work that way - there's a reaction between the materials that breaks electrons free, and so you get electricity. |
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| Solar cells work on the same principle
of a battery, it uses light, photons,
to break off electrons, and with some very cunning materials engineering,
puts pretty much all the broken-away electrons in one area, and flows them
away out through a wire. The challenge is to increase the amount of sunlight
absorbed, minimize reflected sunlight, keep freed electrons from recombining
too soon to be used, and by doing all this, maximize the conduction of
electrons flowing through the cell.
There are many different materials used in solar panels, though the best ones seem to mostly use silicon-based materials. There are two types of silicon used in a single solar cell; two sheets of the materials are pressed together with metal contacts to make a cell. The top is usually mixed with elements so as to give it a negative charge (also called n-type material) and the lower sheet has a positive charge (also called p-type material). The general type of material is called a semiconductor. |
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| A single cell is not very powerful; it doesn't generate very much electricity at all. That's why cells are grouped into modules, and modules grouped into arrays. |  |
For more information, as well as an in-depth description of all the assorted forms of solar power, visit the U.S. Department of Energy's photovoltaics page (which is where we got all of these pictures).