There are three main types of solar panel:Monocrystalline, Polycrystalline and Amorphous. Sometimes this webbing sling can be quiteconfusing, but its actually quite simple, since it refers to the structure ofthe silicon that is used in the modules. The vast majority of commercially available PV systems use one of thesethree types of panel. Themost widely used panels are monocrystalline also known as single crystalsilicon. They are called such because they are cut from a single piece ofcontinuous crystal which is formed into a cylinder. The cylinder is cut intowafers which are then mounted on a board in modules. Because they are cut froma single piece of crystal, they come in a single colour, usually dark blue.
These panels have the best power output at around 140-170 Watts per squaremetre of panel installed. Because they are so efficient this tends to make themmore expensive than the other two types of panel but the good news is that theyare therefore very well suited to customers who have limited space on theirroofs or who want to generate as much electricity as possible. Polycrystallinepanels were introduced in around 1981. They are undoubtedly the cheapest of thethree types, but they are also less efficient at around 120 135 W per m²installed. The reason why they are less efficient than monocrystalline isbecause rather than being available as a single piece of crystal, they are madeof melted crystal which is poured into a mould. They are usually made fromleft-over bits of crystal from other manufacturing. Because they come from amould they can be cut into a square shape, rather than the hexagonal shape ofmonocrystalline cells, which helps to reduce excess space.Amorphouspanels are even less efficient than polycrystalline and have generally used insmall electrical appliances such as electric calculators, however becauseamorphous panels do not degenerate in extreme heat, unlike monocrystalline andpolycrystalline panels, they have often been used in areas subjected to hightemperatures. Increasingly,there are other types of solar panel moving on to the market. One of the latestforms, and increasingly becoming popular is BIPV or Building IntregratedPhotovoltaic.
This can be applied in the form of thin-film solar PV which is athin film of PV material laid upon a silicon substrate. One of the benefits ofthin film is that it can be laid on flat roofs integrated into a flexiblepolymer roofing membrane.Over the years the efficiency of BIPV hasbeen increasing dramatically and it is popular because it can be integratedinto the architecture of buildings, for example in the form of glass panels inwindows and roof membranes. Existing buildings can also be retrofitted withBIPV and the overall advantage is that this material replaces existing buildingmaterials, thereby reducing costs, as well as helping to generate electricityand thus saving on energy bills. Understandably therefore, BIPV is very popularwith builders and architects.ý1eeHýzýý*useholderswhen the excess is exported to the national grid. Additionally, with regard tocost, analysis by Queens University in Kingston, Ontario, indicates that inmany areas the PV solar panels are approaching price parity with moretraditional forms of electricity.