The characteristics of monocrystalline silicon solar cells:
1. High photoelectric conversion efficiency and high reliability;
2. Advanced diffusion technology to ensure the uniformity of conversion efficiency throughout the film;
3. Using advanced PECVD film forming technology, the surface of the battery is coated with a dark blue silicon nitride anti-reflection film, and the color is uniform and beautiful;
4. Apply high quality metal paste to make back field and electrode to ensure good conductivity.
Polycrystalline silicon can be used as a raw material for drawing single crystal silicon, and the difference between polycrystalline silicon and single crystal silicon is mainly manifested in physical properties. For example, in terms of anisotropy of mechanical properties, optical properties, and thermal properties, it is much less pronounced than monocrystalline silicon; in terms of electrical properties, polycrystalline silicon crystals are much less conductive than monocrystalline silicon, and even have little conductivity. In terms of chemical activity, the difference is minimal. Polycrystalline silicon and single crystal silicon can be distinguished from each other in appearance, but the true identification must be determined by analyzing the crystal plane direction, conductivity type and electrical resistivity of the crystal, which is in short supply and has a broad development prospect. Because of this, many people say that whoever masters polysilicon and microelectronics technology will master the world.
Monocrystalline silicon and polycrystalline silicon also play a huge role in solar energy utilization. Although at present, to make solar power have a large market and be accepted by the vast number of consumers, it is necessary to improve the photoelectric conversion efficiency of solar cells and reduce production costs. From the current development process of international solar cells, it can be seen that the development trend is monocrystalline silicon, polycrystalline silicon, ribbon silicon, and thin film materials (including microcrystalline silicon films, compound-based films and fuel films).
From the perspective of industrialization, the focus is on the development of single crystals to polysilicon and thin films. The main reasons are:
A. There are fewer and fewer head and tail materials available for solar cells;
B. For solar cells, the square substrate is more cost-effective, and the polycrystalline silicon obtained by the casting method and the direct solidification method can directly obtain the square material;
C. The production process of polycrystalline silicon is continuously progressing. The fully automatic casting furnace can produce more than 20 kg of silicon ingot per production cycle (50 hours), and the size of the crystal grains reaches the centimeter level;
D. Due to the research and development of the cost process in the past ten years, the process has also been applied to the production of polycrystalline silicon batteries, such as the selection of corrosion emission junctions, back surface fields, corroded suede, surface and bulk passivation, fine metal grids. Electrode, using screen printing technology to reduce the width of the gate electrode to 50 microns, the height of more than 15 microns, rapid thermal annealing technology used in the production of polysilicon to greatly shorten the process time, single-chip thermal process time can be within one minute Upon completion, the cell conversion efficiency achieved on a 100 square centimeter polycrystalline silicon wafer using this process exceeds 14%. According to reports, the current efficiency of cells fabricated on 50-60 micron polycrystalline silicon substrates exceeds 16%. Using mechanical passenger groove and screen printing technology, the efficiency is over 17% on 100 square centimeters of polycrystals, and the efficiency of mechanical engraving is 16% on the same area. The buried gate structure is used, and the mechanical groove is on the 130 square centimeter polycrystal. The battery efficiency reached 15.8%.
(1) Monocrystalline silicon solar cells
At present, the photoelectric conversion efficiency of monocrystalline silicon solar cells is about 17%, and the highest is 24%. This is the highest photoelectric conversion efficiency among all kinds of solar cells, but the production cost is so large that it cannot be widely used. And commonly used. Since monocrystalline silicon is generally packaged in tempered glass and waterproof resin, it is durable and has a service life of up to 25 years.
(2) Polycrystalline silicon solar cells
The manufacturing process of polycrystalline silicon solar cells is similar to that of monocrystalline silicon cells, but the photoelectric conversion efficiency of polycrystalline silicon solar cells is much lower, and the photoelectric conversion efficiency is about 15%. In terms of production cost, it is cheaper than monocrystalline silicon solar cells, the material is simple to manufacture, the point of saving is good, and the total cost is low, so it has been greatly developed. In addition, the service life of polycrystalline silicon solar cells is also better than that of monocrystalline silicon solar energy. The battery is short. In terms of performance and price ratio, monocrystalline silicon solar cells are slightly better.
(3) Non-monocrystalline silicon solar cells (thin film type solar cells)
Non-monocrystalline silicon solar cells are new thin film solar cells that appeared in 1976. They are completely different from single crystal silicon and polycrystalline silicon solar cells. The process is greatly simplified, the silicon material consumption is small, and the power consumption is lower. The main advantage is that it can also generate electricity in low light conditions. However, the main problem of amorphous silicon solar cells is that the photoelectric conversion efficiency is low. At present, the international advanced level is about 10%, and it is not stable enough. As time goes by, the conversion efficiency is attenuated.