Polycrystalline

Polycrystalline sometimes also called multicrystalline solar panels are the most common because they are often the least costly. They're the middle choice in the market ... Virtually as good as single cell silicon panels but generally with a more efficiency than thin film solar cells.

Polycrystalline cells can be recognised by a visible grain, a "metal flake effect". The photovoltaic cells are sometimes square in shape, and can have a surface that looks rather like a mosaic. That is because of all the different crystals that make up the module. The rationale polycrystalline solar panels are less expensive than monocrystalline solar cells, is due to the way in which the silicon is made. Basically, the molten silicon is poured into a cast instead of being made into a single crystal.

This material can be synthesized easily by permitting liquid silicon to chill using a seed crystal of the desired crystal structure. Additionally, other methods for crystallizing amorphous silicon to form polysilicon exist such as high temperature chemical vapour deposition ( CVD ).

In the cast process, silicon pieces are liquified in a ceramic crucible and then formed in a graphite mold to form an ingot. As the molten silicon is cooling a seed crystal of the specified crystal structure is introduced to assist formation. Although molding and using multiple silicon cells needs less silicon and decreases the producing costs, it also reduces the potency of the solar panels.

1366 Tech set up by former MIT professor has developed a machine that can produces polycrystalline solar cells about 30 times quicker than current technologies, which should mean lower priced polycrystalline modules in the near future.

Generally speaking, polycrystalline panels have an efficiency that is about seventy pc to 80% of an equivalent monocrystalline solar cell. The most highly effective polycrystalline panels are built by Mitsubishi Electric Corporation. In Feb 2010, Mitsubishi set 2 world records for photoelectric conversion potency in polycrystalline silicon photovoltaic ( PV ) cells, which was attained by reducing resistive loss in the cells. The conversion potency rates have been confirmed by the Nation's Institute of Advanced Industrial Technology and Science ( AIST ), in Japan.

Another one of the Earth records, which Mitsubishi Electrical has now renewed for the 3rd uninterrupted year, is a 19.3-percent efficiency rating for photoelectric conversion of a practically-sized polycrystalline silicon PV cell of 100 squared centimeters or bigger, with the PV cell measuring roughly 15cm x 15cm x 200 micrometers. The rating is 0.2 points higher than the organization's previous record of 19.1 %. The second world record, achieved with the same technologies in an ultra-thin polycrystalline silicon PV cell measuring approximately 15cm x 15cm x 100 micrometers, is an efficiency rating of 18.1 p.c, a 0.7-point improvement over the company's previous record of 17.4 percent.

Currently the solar industry is investing tons of money in R&D to find ways to increase manufacturing costs and augment overall efficiency of the solar modules. As you can see from the work done by Mitsubishi, these enhancements are primarily incremental in nature and are more on the producing side than on the efficiency side. .

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