Thin Film Solar Cells
The high demand for crystalline silicon PV cells has outstripped production, which has caused an increase in the prices of crystalline cells. As a result, a number of PV cell manufacturers have begun using less expensive semiconductor materials including amorphous silicon (a-Si), cadmium telluride (CdTe), copper indium diselenide (CIS) or copper indium gallium selenide (CIGS). These materials are good light absorbers and are fairly thin. Among these, CdTe is the most prominent technology being followed currently, followed by a-Si and CIGS.
They are known as thin-film because they are deposited in very thin layers on stainless steel, glass or a flexible substrate. The thickness of the film is less than 1 micron. Like c-Si, thin-film PV cells are combined into modules and laminated to protect them from the elements. They are less expensive than c-Si cells, but their demonstrated energy conversion efficiency is only around 8%. The advantage of thin-film technology is that it can be applied over large areas, providing more opportunity to generate electricity in cloudy conditions.
The production process of thin-film solar panels is different when compared to crystalline silicon panels. The most common thin-film manufacturing process is chemical vapor deposition. In the chemical vapor deposition process, gases react inside a chamber to form a condensate that settles uniformly onto a glass substrate. This method reduces the utilization of costly materials and energy as compared to conventional crystalline technologies, thereby dramatically reducing the total cost of PV modules.