Monocrystalline cells are being used for over 20 years. They are typically used in high reliability applications such as telecommunications. Well known brands include BP, Sharp and Siemens. Typically solar panel prices considered on per watt basis. Monocrystalline conversion efficiency of sunlight to electricity is much the same as for polycrystalline cells. However, they too experience a significant reduction in output at elevated temperatures, although the effect is not as large as for polycrystalline panels. A reduction of between 12% and 15% can be expected on a sunny day.
Panels made from amorphous cells have been used in portable items such as pocket calculators for many years, but it has only been since about 1998 that they have become available for rooftop applications in Australia. The best-known brands are UniSolar and BeyondPV. They have recently become very popular because unlike the other types, their output does not decrease in elevated temperatures. Indeed, one independent test showed a slight increase in output. This means that the actual output is likely to be close to the nameplate rating. Their conversion efficiency of sunlight to electricity is 9.3%, about half that of polycrystalline or monocrystalline panels. Thus an array of amorphous panels will require about twice as much roof space as an array with a similar rating using other types of panels. This can limit their application when the amount of unobstructed roof space is limited