Photovoltaics

Credit: Flickr user Acid Pix via Creative Commons
Credit: Flickr user Acid Pix via Creative Commons

The technology used in solar panels is known as photovoltaics or ‘PVs’. Solar panels are non-mechanical devices containing solar cells (PVs) that convert sunlight directly into electricity (1). The main types of PVs are crystalline-silicon (c-SI) and thin-film technology.

Crystalline Silicon (c-Si)

There are two kinds of c-Si cells; monocrystalline and polycrystalline.

Monocrystalline cells are created from a single crystalline structure (2). Efficient processing has reduced the cost of monocrystalline cells but the manufacturing process can be more wasteful and a little more expensive then polycrystalline cells (2). The individual cells on older monocrystalline panels may be circular in shape whereas in modern monocrystalline panels they are manufactured to be square to maximise the surface area, leaving no voids between cells (2).

Polycrystalline cells are manufactured by loading silicon rocks in to a mould and melting them to produce square ingots. This manufacturing process generates less waste and cost (2). Polycrystalline cells may be more cost-effective to produce but they tend to be slightly less efficient at converting energy (2). This may mean that more solar panels are required to produce the same amount of energy as monocrystalline cells. Generally, the differences between the two are slight and may only become a concern if space is limited (2).

Thin-Film Technology

Thin-film photovoltaics come in three main forms; cadmium telluride (CdTe); copper, indium, gallium, selenide (CIGS) and amorphous silicon (a-Si). The main difference between thin-film cells and crystalline silicon cells is that thin-film can be deposited or ‘painted’ in layers on many different types of material such as glass, flexible plastic and metal (2).

Cadium Telluride (CdTe)

This tends to be the more efficient of the thin-film technologies. It is often processed on glass making it inflexible which can cause problems during manufacturing and installation compared to other thin-film photovoltaics (2). Cadium Telluride photovoltaics tend to cost less than the crystalline silicone photovoltaics discussed above (2).

Copper, Indium, Gallium, Selenide (CIGS)

This thin-film technology is getting closer to crystalline silicon cells in efficiency but challenges still exist in manufacturing which tends to make these panels more expensive (2). CIGS are sensitive to moisture which can lead to these PVs to cease working if not appropriately sealed (2).

Amorphous Silicon (a-Si)

Whilst these panels are the lowest in efficiency and more expensive that c-Si panels they are also easy to manufacture and are lightweight, durable and flexible (2). These panels tend to be used in electronics and for use on the move such as foldable and rollable panels used in outdoor equipment like tents, backpacks and pocket sized panels to charge mobile devices (2)
Thin-film photovoltaics are a relatively immature technology being the least efficient and most expensive on the market but improvements are expected during the next 10 years (2).

References

  1. http://www.eia.gov/energyexplained/index.cfm?page=solar_photovoltaics
  2. Kernes, J. (2017) What’s the difference between solar panels? Machine Design. 89.1: 30-36. Business Source Elite. EBSCOhost. [Accessed 9 February 2017].