Types of Solar Panels
There are three basic types of solar cell
Crystalline solar cells are wired in series to produce solar panels. As each cell produces a voltage of between 0.5 and 0.6 Volts, 60 cells are needed to produce an open-circuit voltage of about 40 Volts in a standard panel.
– made from a single large crystal, cut from ingots. Higher quality, more efficient, but also slightly more expensive. Somewhat better in low light conditions than other types.
– basically cast blocks of silicon which may contain many small crystals. This is probably the most common type right now. Slightly less efficient than single crystal cells, but once set into a frame with 60 or so other cells, the actual difference in watts per square metre is low.
Crystalline cells generally have a longer lifetime than the amorphous variety.
The diagram shows how the two types of panel are manufactured.
– technology most often seen in small solar panels, such as those in calculators or garden lamps, although amorphous panels are increasingly used in larger applications. They are made by depositing a thin film of silicon onto a sheet of another material such as steel. The panel is formed as one piece and the individual cells are not as visible as in other types.
The efficiency of amorphous solar panels is not as high as those made from individual solar cells, although this has improved over recent years to the point where they can be seen as a practical alternative to panels made with crystalline cells. Their great advantage lies in their relatively low cost per Watt of power generated. This is offset, however, by their lower power density; more panels are needed for the same power output and therefore more space is taken up. As a result they are probably the least common of the three types of solar cell.