1. Silicon solar cells
Silicon solar cells are classified into three types: monocrystalline silicon solar cells, polycrystalline silicon thin-film solar cells, and amorphous silicon thin-film solar cells.
Monocrystalline silicon solar cells have the highest conversion efficiency and the most mature technology. The highest conversion efficiency in the laboratory is 24.7%, and the efficiency in mass production is 15% (18% as of 2011). It still dominates in large-scale applications and industrial production. However, due to the high cost of monocrystalline silicon, significantly reducing its cost is difficult. To save silicon materials, polycrystalline silicon thin films and amorphous silicon thin films have been developed as alternatives to monocrystalline silicon solar cells.
Compared to monocrystalline silicon, polycrystalline silicon thin-film solar cells are less expensive and more efficient than amorphous silicon thin-film cells, with a laboratory-scale conversion efficiency of 18% and an industrial-scale production efficiency of 10% (17% as of 2011). Therefore, polycrystalline silicon thin-film cells are expected to dominate the solar cell market soon.
Amorphous silicon thin-film solar cells are low-cost, lightweight, and have high conversion efficiency, making them suitable for large-scale production and possessing great potential. However, their stability is limited by the photoelectric efficiency degradation effect caused by their material composition, directly affecting their practical applications. If the stability issues and conversion efficiency problems can be further resolved, then amorphous silicon solar cells will undoubtedly be one of the main development products in the solar cell industry.
2. Polycrystalline thin-film solar cells
Polycrystalline thin-film solar cells made of cadmium sulfide and cadmium telluride have higher efficiency than amorphous silicon thin-film solar cells, lower cost than monocrystalline silicon cells, and are easier to mass-produce. However, because cadmium is highly toxic and causes serious environmental pollution, it is not the most ideal alternative to crystalline silicon solar cells.
3. Nanocrystalline solar cells
Nanocrystalline chemical solar cells are a newly developed technology, with advantages including low cost, simple manufacturing process, and stable performance. Their photoelectric efficiency is consistently above 10%, and their manufacturing cost is only 1/5 to 1/10 of that of silicon solar cells. Their lifespan can reach over 20 years. Research and development of this type of cell is still in its early stages, but it will gradually enter the market in the near future.
4. Organic thin-film solar cells
Organic thin-film solar cells are solar cells whose core components are made of organic materials. It's understandable that people are unfamiliar with organic solar cells. Currently, over 95% of mass-produced solar cells are silicon-based, while the remaining less than 5% are made from other inorganic materials.
5. Dye-sensitized solar cells
Dye-sensitized solar cells are made by attaching a dye to TiO2 particles and then immersing them in an electrolyte. When the dye is exposed to light, it generates free electrons and holes. The free electrons are absorbed by the TiO2, flow from the electrodes into the external circuit, then through the electrical appliance, into the electrolyte, and finally back to the dye. Dye-sensitized solar cells have very low manufacturing costs, making them highly competitive. Their energy conversion efficiency is around 12%.
6. Plastic solar cells
Plastic solar cells use recyclable plastic films as raw materials and can be mass-produced using roll-to-roll printing technology, making them inexpensive and environmentally friendly. However, plastic solar cells are still in their infancy. It is expected that in the next 5 to 10 years, solar cell manufacturing technologies based on organic materials such as plastics will mature and be put into large-scale use.
