Types of Photovoltaic Panels
The basic physics of photovoltaic (PV) operation can occur in
several different forms of semiconducting material. Silicon can have
three different forms crystalline, poly-crystalline, and amorphous.
Each of these will be discussed in the following paragraphs.
The crystalline form of Si is currently the most used. It is also
the most difficult to create. A crystal is a lattice of very pure
silicon. Each atom is regularly spaced in a highly organized
pattern. Each PV cell is made from the section of a single large
crystal. This is the same method used for manufacturing integrated
circuits for computers. The crystals for PV panels do not have to be
as pure and perfect as they do for computer chips but each cell is
still a single crystal.
There is also poly-crystalline PV cells. As the name might suggest
each, it is a PV cell is made from multiple crystals. It is easier
to grow the polycrystals so this process is cheaper than a
mono-crystalline cell. It is, however, less efficient. Electrons
travel best through an orderly crystal structure. In a
polycrystalline PV cell fewer freed electrons will reach the
electrodes as they are reabsorbed and the crystal boundaries. This
reduces the operational efficiency of the cell.
The final state of Si used for PV cells is its amorphous state. This
is generally considered to be a thin film technology. Thin films
are, not surprisingly,a thin film of material deposited on a
substrate instead of the relatively thick crystals required by the
crystalline forms of Si. In the amorphous state the silicon atoms
have no structure but are all jumbled together. It does not have to
be grown as with the crystalline structure which can lead to a
cheaper production process.
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