Amorphous silicon (a-Si or a-Si:H) solar cells belong to the category of silicon thin-film, where one or several layers of photovoltaic material are deposited onto a substrate.
Some types of thin-film solar cells have a huge potential. These technologies are expected to grow rapidly in the coming years as they mature. In 2011, amorphous silicon solar cells represented about 3% of market.
The word “amorphous” literally means shapeless. The silicon material is not structured or crystalized on a molecular level, as many other types of silicon-based solar cells are.
Most pocket calculators are powered by thin film solar cell made out of amorphous silicon. For a long time, the low power output of amorphous silicon solar cells limited their use to small applications only.
This problem is partially solved by “stacking” several amorphous solar cells on top of each other, which increases their performance and makes them more space-efficient.
In laboratory conditions, scientists have pushed efficiency rates to 12.5%. The efficiency of amorphous silicon solar cells that are manufactured in high-volume processes ranges from 6% to 9%. Oerelikon set the world record for stable amorphous solar cells to above 10% in 2009.
- Requires much less silicon. Amorphous silicon is a direct-bandgap material, and therefore only require about 1% of the silicon that would`ve been used to produce a crystalline-silicon based solar cell.
- The substrates can be made out of inexpensive materials such as glass, stainless steel and plastic.
- Theses are the two major reasons why amorphous silicon solar cells have a great potential to one day become cheaper than mono- and polycrystalline solar cells.
- Can be made flexible and lightweight. A flexible thin-film module enables us be much more creative when it comes to applications. They can be placed on curved surfaces and will probably in the future be incorporated into clothing! Strength and flexibility is determined by the surfaces or substrates the thin film solar cells are attached to.
- Thin-film solar cells perform relatively well under poor lighting conditions and are not affected as much by shading issues.
- Amorphous silicon can be deposited onto substrates at temperatures below 300°C, which makes the technology a good candidate for flexible substrates and roll-to-roll manufacturing techniques.
- Amorphous thin-film solar cells have lower efficiency rates. The technology is new, and efficiency rates are thought to increase with technological breakthroughs in the near future.
- Thin-film solar panels tend to degrade faster and not last as long as mono- and polycrystalline solar panels.
- You would have to cover a larger surface with amorphous silicon solar panels than crystalline-based solar panels for an equal output of electrical power.
The bottom line is this: Amorphous silicon solar cells show a lot of promise. They are lighter, more flexible, and potentially less expensive to produce. On the other side, the technology has to mature to compete against mono- and polycrystalline solar.