In solar power systems, the most complex component of technology should be solar cells. It can be said that solar cells are the core of solar power generation systems, and their development and production directly affect the popularity and development of solar power generation.
The main principle of solar cells is to use a semiconductor material to place a thinner N-type semiconductor on a thicker P-type semiconductor. When photons hit the surface of the device, electrons diffuse from the junction of the P-type and N-type semiconductors. The current can be extracted by the metal conductors at the upper and lower ends.
The types of solar cells vary according to the materials used. Solar cells can be classified into: 1. silicon solar cells; 2. batteries made of inorganic compounds such as gallium arsenide III-V compounds, cadmium sulfide, copper indium selenium and the like; 3. Solar cells prepared by functional polymer materials; 4, nanocrystalline solar cells, etc.
Silicon is the most ideal solar cell material, which is the main reason why solar cells are mainly silicon materials. In the above batteries, the single crystal silicon solar cell has the highest conversion efficiency and the most mature technology, and the photoelectric conversion efficiency can reach 23.3%. In the manufacturing process, techniques such as surface texturing, emitter passivation, and zone doping are generally employed. However, due to the price of single crystal silicon material and the corresponding cumbersome process, the cost price of single crystal silicon is high, and it is very difficult to reduce the cost significantly, and the large-scale popularization of solar power generation cannot be realized.
With the continuous development of new materials and the development of related technologies, solar cells based on other materials are increasingly showing attractive prospects. Photovoltaic cells, amorphous silicon and crystalline silicon hybrid thin film photovoltaic cells.
If the characteristics of single crystal silicon are high efficiency and high cost, the problem of other material batteries is undoubtedly low cost and weak conversion. Compared with monocrystalline silicon solar cells, in addition to polysilicon, cadmium telluride, etc., the photoelectric conversion efficiency of other materials is generally less than 15%.
The development of solar cells in China China began researching solar cells in 1958 and first applied it to satellites launched in China in 1971. Solar cells were used on the ground in 1973. Due to price and production constraints, the market is developing very slowly. In addition to being a satellite power source, solar cells on the ground are only used in low-power power systems such as beacon lights and railway signal systems.
In 2002, the relevant state ministries and commissions launched the “Power-free plan for power-free townships in the western provinces” to solve the problem of electricity use in the power-free townships in the seven western provinces through photovoltaic and small-scale wind power generation. The launch of this project has greatly stimulated the solar power industry. Several solar cell packaging lines have been built in China, which has led to a rapid increase in the annual production of solar cells.