Solar electric or PhotoVoltaic (PV ) panels
A Photo Voltaic (PV) panel converts incident solar radiation into DC electricity. There are a few variants.
Poly Crystalline Panel
Probably the most widely used PV panel today. The silicon wafers originate from silicon blocks, which themselves are moulded from excess silicon recovered during the manufacture of microchips, as opposed to the now superseded, mono crystalline panels that were composed of wafers from a single silicon crystal.
This new approach to wafer production gives a slightly cheaper raw material, however this is at the cost of efficiency as it is harder to get an even distribution of the doping elements, which are the rare earth metals with the highly efficient conductive properties.
This price vs efficiency trade-off has been largely market driven as the cost of systems becomes more competitive across the different manufacturers.
½ Cell Panels
These are a fairly recent innovation, brought about by halving the silicon wafer, resulting in the electrons have a shorter distance to travel before they are picked up in the lower-resistance wires thus increasing efficiency. The trade-off here is that there are more gaps between the wafers, and those gaps add up and result in a slightly increased panel size.
Bi-Facial Panels
These panels have a clear backing sheet to the panel, allowing some of the reflected radiation to be used and thus increasing the power delivery of a given size of panel. There is more benefit if the panels are free standing e.g., in a ground array, rather than tight to a roof where reflected radiation to the back of the panel is greatly reduced.
Unframed Panels
These panels comprise just the glass sheet and the silicon wafers, allowing them to be fitted into standard glazing systems. Some offer a wider spacing between wafers allowing more light through making them suitable for car ports and conservatory roofs. Because of the low manufacturing numbers, availability is limited and the cost per watt tends to be higher.
Black, All Black and coloured panels
Natural aluminium frames with a white backing sheet are the cheapest to manufacture however the aesthetics are not proving popular and there has been a widescale move to black panels in black anodised frames, and to black frames with a black backing sheet, resulting in an all-black panel, with some manufacturers even colouring the surface wires black to try to produce a truly all-black panel.
It is also possible to colour the silicon to give red, green and blue finishes although there is a significant loss of performance and an increased cost per watt.
