Overview:

Product Description:

Traditional PV cells are made from silicon (Si), which, after oxygen, is the second most abundant element in the Earth’s crust.  However, PV-grade crystalline silicon must be highly refined to a purity of 99.9999%.  Melted silicon is ‘grown’ into ingots, or rods, by dipping a seed into the melted silicon and allowing it to cool slowly.  These ingots are then sliced or sawn into thin Si wafers, wasting 20% of the valuable silicon as sawdust. The refining process and sawdust waste add considerably to the embodied energy of crystalline silicon, but with a wafer lifetime of 25 years, the embodied energy will be regained several times over.

Two types of crystalline silicon technologies are currently used in photovoltaics: monocrystalline and multicrystalline. Both types arrange their Si molecules into a crystal lattice formation, which provides the structure. Impurities, however, are more common in multicrystalline silicon leading to lower efficiencies, uniformity, and cost.

Crystalline Si basics:

• 4-year energy payback period  (C. Bankier and S. Gale, Energy Bulletin)  This payback time may be reduced if the module frame is made of recycled materials. (aluminium)
• Highly temperature-sensitive
• Typical monocrystalline cell efficiency = 15 – 17%
• Typical multicrystalline cell efficiency = 13 – 15%

Australian manufacturers of Crystalline Si PV Modules:

• BP Solar
• Origin Energy

Availability:

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