These include zero greenhouse gas emissions, no residual waste, zero noise, and low operating risk. With technology advancement in recent decades, solar cells have more than doubled in efficiency and are only a fraction of the price of the first generation cells – making solar PV energy more adaptable for commercial and residential use then ever before.

But as the PV industry grows, so does the confusion in the general market place on the type of PV cells available. The most common PV products in the commercial market are amorphous silicon, polycrystalline, monocrystalline and back contact modules, with respective working efficiencies of 5-7 per cent, 8-11 per cent, 12-13 per cent and 16-20 per cent.

Amorphous silicon is one of a number of thin film technologies. The module is made by depositing silicon on to low cost substrates like glass or plastic. The silicon has a non-crystalline structure and is typically cheaper to produce than the other PV technologies mentioned in this article. However, as the work efficiency of an amorphous module is limited to approximately 5-7 per cent - one third of the efficiency of back contact modules - the cost benefits need to be weighed against higher installation costs and space restrictions - especially with residential grid connect systems.

Polycrystalline, monocrystalline and back contact cells are all made by silicon wafers - but using different methods. Polycrystalline cells are made by pouring molten silicon into a mould, allowing it to set, and then slicing it into wafers.

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Polycrystalline cells are easy, cheap and less labour intensive to cast compared with monocrystalline cells, however, the casting process deforms the silicon crystal structure, and the working efficiency drops to two-thirds of the efficiency of monocrystalline cells. In the meantime, almost half the silicon is lost as sawdust in the production process.

A monocrystalline cell is formed by drawing a large cylindrical crystal from a molten silicon bath (instead of pouring and casting). This process is slow and must be carefully controlled. The wafers are then trimmed to a square shape to increase cell packing density. These cells have a near perfect crystal structure that offers excellent cell performance. Monocrystalline modules have a high efficiency of 12-13 per cent and are particularly good at working at low light levels.

Back contact monocrystalline modules are made of monocrystalline cells. Unlike other conventional cells that either print or embed the strings on the front surface, back contact cells are designed with all the electrical contacts on the back surface. This revolutionary concept (unique to Sun Power solar modules) increases the surface contact of the cells to solar isolation to the greatest extent, and enables the cells efficiencies to reach more than 20 per cent.

Thus a system with predefined capacity will take less space using back contact modules than by using conventional modules. This means installation costs can be greatly reduced, and the opportunity for future capacity upgrades increased. In addition, the elimination of strings gives the module a polished, flawless surface appearance that makes it the best choice overall for aesthetic consideration.