In the field of photovoltaic is gradually replacing isostatic graphite, in the initial state of the wind trend

In the field of photovoltaic is gradually replacing isostatic graphite, 

in the initial state of the wind trend

China's photovoltaic industry experienced rapid development in 2007 and 2010, in 2012 has been a state of overcapacity, but also intensified the industry reshuffle.

In 2013, the solar photovoltaic industry in monocrystalline silicon and polysilicon at the same time the development of the pattern, when polysilicon photovoltaic conversion efficiency is not as high as monocrystalline silicon, but the cost has a great advantage. Monocrystalline silicon process is used in the direct-draw monocrystalline silicon process, high cost, but the PV conversion efficiency has an advantage.

Direct-drawn monocrystalline silicon furnace has been used in a large number of carbon hot field materials. These carbon materials are irreplaceable by other materials. Take the crucible inside the direct-draw monocrystalline silicon furnace as an example, the high-purity silicon material has to be melted at about 1500°C, which needs to be carried by a quartz crucible, but the high-temperature strength of the quartz crucible is too low to carry 200-300 kg of silicon material, so a graphite crucible must be set outside as a carrying part. Here the advantage of carbon material comes into full play, because carbon material is the only material whose mechanical properties do not decrease but increase at high temperatures.

The 2013 direct-draw single-crystal silicon furnace crucible is only 24-28" in diameter and loaded with less silicon, and the graphite material can fully withstand this load. The graphite material is mainly isostatic graphite.

By 2021, the situation has changed dramatically. 2021 direct-draw monocrystalline furnaces have a crucible diameter of 36" and can be loaded with more silicon, up to 700-800 kg of silicon at a time. Carbon crucibles are required to become larger and stronger. This is when the cost of isostatic graphite rises dramatically and is gradually replaced by carbon/carbon composites.

There is a more important reason why isostatic graphite is being replaced by carbon/carbon. Because isostatic graphite is a brittle material, it fractures without a precursor, so in case of crucible damage, the molten silicon will burn through the bottom of the furnace. Carbon/carbon composites, on the other hand, are carbon fiber-reinforced carbon matrix composites, which do not suffer from brittle fracture accidents and are much safer.

Large-size isostatic graphite cost increases, slowly approaching the cost of carbon / carbon composites, and low safety, it is only natural to be replaced. Therefore, the current direct-draw single-crystal silicon furnace carbon structure materials, there are still heaters still using high conductivity graphite materials, the other gradually replaced by carbon-carbon composites.

In addition to graphite reasons, carbon / carbon composite materials can replace graphite materials another reason, is the carbon / carbon technology has developed rapidly in the past few years. The market price alone, a kilogram of carbon / carbon composite material market price in the past 2000-3000 yuan, now has been reduced to 1100-1200 yuan per kilogram. Greatly reduce the cost per watt of solar photovoltaic power generation components.

In 2022, China can achieve grid parity for solar PV power generation. After solar power is able to move away from subsidies and develop sustainably, what will be ushered in will be exponential growth. After years of competition with polysilicon, monocrystalline silicon is gradually phasing out the market for polysilicon.

As the production of monocrystalline silicon straight pull monocrystalline silicon process, has become the mainstream. The carbon/carbon composite material, which is an important material in the direct-draw monocrystalline silicon furnace, and is a consumable that needs to be replaced every 1-2 years, will see more rapid development.

Carbon / carbon composite materials, is a carbon fiber reinforced carbon matrix materials, carbon fiber usage is growing rapidly year by year. The current carbon / carbon composites are in short supply, gross margin is not less than 60%, it is in the initial state of the wind trend.