Ever since PERC technology is getting popular, mono-Si products continue to threaten the market share of multi-Si products. Therefore, multi-Si manufacturers start to pay close attention to black silicon technology, hoping to improve the lower cell conversion efficiency problem caused by diamond-wire cut wafers and find new market opportunities for large multi-Si capacities.
Compared with traditional slurry-wire cut, diamond-wire cut is faster and can come up with more-stable-quality wafers. Wafer cost can be reduced to US$ 6-10 cents/piece too using diamond-wire cut. However, since the surface of multi-Si wafer using diamond-wire cut is too smooth, sunlight can easily be reflected and cannot be absorbed by the cell, which leads to lower conversion efficiency. Because of this, surface etching must be performed. One of the technologies with high visibility is called black silicon.
Two types, three production processes
Black silicon is an existing technology that comes back with the diamond-wire cut wafers. In 2016, quite a few manufacturers have begun to conduct research into black silicon, including Canadian Solar, JA Solar, Jinko Solar, BYD, Kyocera, and some Taiwanese makers.
Black silicon is mainly divided into two types – dry and wet etching, with a variety of classification. There are three major categories in the current market for black silicon technology – dry etching, wet etching, and additive. Additive is a type of wet etching but without the silver nitrate solvent used in standard wet etching process. The three types of production processes are listed below:
Taking current technology development and equipment cost into account, Analyst of EnergyTrend believes that black silicon technology focuses more on additive production process in 2017, while dry etching is still developing. Yet, how wet etching uses the silver nitrate solvent has environmental concerns and is relatively unfavorable. In addition, wet etching is less competitive than dry etching in terms of efficiency increase and less competitive than additive in terms of cost reduction. As a result, wet etching’s competitiveness remains to be seen.
Main competitor is conventional mono-Si
If black silicon multi-Si cell works with PERC technology, the conversion efficiency can reach 19-20%, plus the cost reduced by using diamond-wire cut, its C/P ratio will directly challenge the position of conventional mono-Si cell. Meanwhile, mono-Si wafer capacity is not as sufficient as multi-Si wafer, which is difficult to win over the market share of multi-Si wafer and thus open a new market for black silicon multi-Si cell.
Mono-Si PERC cell will enter the mainstream high-efficiency market in 2017 as the technology matures. We can see this from manufacturers’ expansion and high market demand of mono-Si PERC cells.
Analyst of EnergyTrend forecasted that the black silicon technology will be clear in 1H17 and enter the mass production stage in 2H17. The market response to the black silicon multi-Si cell will determine the future development of black silicon.
(Photo: The surface of multi-Si wafer etched by additive method; Photo Credit：Schmid)