Silicon wafer is the basis of photovoltaic products. It is further processed into crystalline silicon cells, and the cells are arranged, packaged and combined with other auxiliary materials to become the smallest effective power generation unit of the photovoltaic system-solar panels.

　　Photovoltaic silicon wafers currently have two product forms, monocrystalline silicon and polycrystalline silicon, but there is a generation gap between them.

　　Monocrystalline silicon has excellent crystal quality, electrical properties, mechanical properties, etc., and has better photoelectric conversion efficiency, but the cost is relatively high, and it has not been widely used in the initial stage. Polysilicon has dominated the market for a long time by relying on its price advantage.

　　With the continuous progress of the production process, the production cost of monocrystalline silicon has dropped rapidly. At the same time, the new generation of battery technology represented by PERC cells (Passivated emitter rear contact solar cells, the current mainstream photovoltaic cells) is right. The utilization rate of monocrystalline silicon wafers is higher, which further opens up the gap in photoelectric conversion efficiency.

　　Under the declining cost and conversion efficiency, monocrystalline silicon has risen rapidly. As of the end of 2020, the market share of monocrystalline silicon wafers has increased from 20% in 2016 to more than 90%, realizing a full replacement of polycrystalline silicon wafers.

　　Silicon wafer manufacturing focuses on reducing production costs, and one of the measures is to increase the size of the wafer. The increase in the area of the silicon wafer means that the total power of the cells/modules produced per unit time is higher, and the corresponding production cost per watt will be diluted.

　　At present, the 156.75mm and 158.75mm specifications of photovoltaic silicon wafers are rapidly being phased out, 166mm has become the mainstream, and the production capacity of 182mm and 210mm has been continuously improved and applied. The reason is that large-size silicon wafers have higher power generation efficiency, and the non-silicon costs of end products (energy, manpower, auxiliary materials, etc. consumed in production) are lower.

　　Decrease in the thickness of silicon wafers is another long-term trend-this effectively reduces silicon consumption, increases the number of wafers, and then achieves cost reduction. At present, the mass production thickness of monocrystalline silicon wafers is 170~180μm, and some manufacturers have been able to realize the production of 140μm monocrystalline silicon wafers, and there is considerable room for cost reduction in the future.

　　Blade loss is the main source of loss in the silicon cutting process. Compared with the traditional cutting method, the new generation of diamond wire cutting technology has a series of advantages such as faster cutting speed, higher yield, and lower single chip loss. These advantages help to help silicon wafers reduce production costs.

　　Although there are battery routes that do not use silicon wafers, they are far from commercialization and cannot shake the dominance of silicon batteries. In the next few years, how to produce silicon materials more efficiently, reduce the cost of silicon wafers, and reduce subsequent installation costs will still be the persistent direction of the photovoltaic industry.

　　Lithium-ion battery (LIB) has become the main energy storage solution in modern social life. Among them, lithium iron phosphate batteries are a perfect replacement for lead-acid batteries, and they are the first choice for grid-connected peak shaving, off-grid energy storage, photovoltaic energy storage, UPS, data center and other industries.

　　Solar power generation system with lithium battery energy storage system is a very promising clean energy.