AG3 battery.Continuous crystal pulling gradually becomes the mainstream of single crystal rod pulling technology, helping to reduce the cost of photovoltaic electricity.

　　Improving efficiency and reducing costs have always been the efforts of the photovoltaic industry. In recent years, a series of technological innovations from silicon wafers, cells to components have continued to improve the conversion efficiency of photovoltaic power generation and reduced the cost of electricity. In this context, improving and optimizing silicon crystal growth technologies such as single crystal rods, polycrystalline and quasi-single crystal ingots to produce higher quality and lower cost silicon rods and silicon ingots will enhance the competitiveness of the photovoltaic industry and accelerate the development of the photovoltaic industry. It is particularly important to achieve grid parity on the power generation side.

　　The reporter learned from the industry that single crystal rod pulling technology is transitioning from multiple charging crystal pulling (RCz) to continuous crystal pulling (CCz). Since CCz requires high-quality granular polysilicon raw materials, the promotion of CCz will have a profound impact on China's photovoltaic grade polysilicon production pattern. CCz also requires a quartz crucible with a lifespan of 500 hours, and the localization of high-quality quartz crucibles is also an important issue.

　　According to industry insiders, CCz can effectively reduce the time, crucible cost and energy consumption of single crystal rod drawing, and the resistivity of CCz-produced crystal rods is more uniform, narrower in distribution and higher in quality. In addition, the automation and intelligence of single crystal rod production will help increase production capacity and optimize the consistency of the crystal growth process.

　　Previously, many leading companies have already laid out their plans. In April 2018, GCL-Poly announced that it would build 20GW CCz monocrystalline production capacity in Qujing, Yunnan. In August 2018, LONGi announced the signing of a CCz high-efficiency monocrystalline cooperation agreement with Aixu Solar.

　　At the same time, the polycrystalline ingot casting process is being upgraded from G6 ingot furnace to G7 or even G8 technology. While significantly increasing production capacity, it is necessary to continue to optimize hot zones, auxiliary materials, casting processes and equipment. Through advanced nucleation technology and high-purity crucibles, conversion efficiency can be improved and resistivity distribution optimized. Cell efficiency can also be improved by reducing dislocation density, oxygen content and narrower resistivity. Among them, doping gallium in the ingot casting process can effectively solve the light attenuation problem of polycrystalline PERC cells.

　　Ingot-type single crystal has the advantages of high minority carrier lifetime, low dislocation density and low cost. It is an important development direction of silicon crystal manufacturing. GCL-Poly has started accepting orders for ingot single crystal silicon wafers in 2018. In addition, direct silicon wafer technology has lower silicon consumption and energy consumption. In 2018, the average efficiency of high-efficiency cells produced with direct silicon wafers has reached 20.5%, which has also attracted widespread attention in the photovoltaic industry. N-type monocrystalline cells have the advantages of high minority carrier lifetime, high tolerance to metal impurities, and low light attenuation. N-type monocrystalline production technology also deserves attention.

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