Policy and Industry Dynamics

Policy and Industry Dynamics

Policy and industry dynamics

Who Will Lead Efficiency Improvement? PERC and Black Silicon Ruling Their Own Regime

Date/Time2016-05-22 Print Font Size:TT

While PERC is gradually becoming the pronoun of highly efficient technology for P-type cells, black silicon technology, which had been very popular for a time, stages a comeback to promote the further efficiency improvement of polycrystalline cells. The flames of the war between polycrystalline and mono-crystalline silicons have spread from conventional efficiency to the field of high efficiency, and the cost performances, maturities, productivities, and capacity expansion speeds of PERC and black silicon technologies have become the hot discussion topics in the industry again.


Mono-crystalline battle at the end of 2015


Because of the shrinkage of European market, 2015 became the year in which the global market share of mono-crystalline products was the lowest in recent years. Not only the mass production of mono-crystalline PERC cells with high cost performance didn't reach the expectation, but general mono-crystalline products were also confronted with low demand throughout the year due to the too big price difference from polycrystalline products in the first half of 2015.

In the major markets of Europe, Japan, the US, and Asia, modules 270W and 275W, mainstream mono-crystalline products, could be hardly found among the top five products ranked by market share in the second half of 2015. Fortunately, LONGi Corp., the leading manufacturer of mono-crystalline wafers, and its subsidiary LERRI Solar came onto the stage and saved the critical situation. In line with the high-efficient product demand of China's Top Runner Program, they restarted the market share battle between polycrystalline and mono-crystalline products in 2016.


Fig. 1: Main Product Distribution in Major Markets in Q1 of 2016


On the premise of the same installed area, the special case adopting mono-crystalline modules outputs higher wattages, relatively cutting down the unit construction cost of power station. As a result, mono-crystalline product manufacturers constantly uphold the flag of the superiority of mono-crystalline products to polycrystalline ones with respect to power production quantity of system per watt on the side of power station in the hope of increasing the market share of mono-crystalline products.


Since last year, the price difference between mainstream mono-crystalline module advocated by LERRI and polycrystalline module has been reduced to RMB 0.1/W, which has smoothly made the company's name. Meanwhile, "golden cross" of price per watt also arose between polycrystalline and mono-crystalline products on the sides of upstream silicon wafer and cell. Judged from the trend that there were large power stations successively employing mono-crystalline products in China, mono-crystalline products had really won an excellent battle from the end of 2015 to the beginning of 2016.


Fig. 2: "Golden Cross" of Cell Price


Source: EnergyTrend’s monthly price report


As not a few big producers in China raised the output proportion of mono-crystalline products in succession, the situation that the supply of mono-crystalline wafers exceeded demand was soon reversed -- the supply fell short of demand. Besides beginning to expand capacity rapidly, the leading manufacturers LONGi and Zhonghuan also raised price by taking advantage of the favorable situation, making the price of mono-crystalline wafer climb back to US$ 0.90/W after the lunar New Year's Day and continue to this day. However, because the demands in the end market had gradually slowed down since March, the prices of polycrystalline silicon wafer and cell dropped quickly, and the market returned back to the situation that the prices per watt of polycrystalline silicon wafer and cell were lower than those of mono-crystalline products. Variables occurred again for the battle between polycrystalline and mono-crystalline products in the second half this year.


Mono-crystalline and polycrystalline technical routes: PERC and black silicon having their own advantages


The competition between mono-crystalline and polycrystalline products has gradually spread from mainstream market to highly efficient technology. PERC can be used in polycrystalline and mono-crystalline cells, but efficiency improvement realized by mono-crystalline products is more remarkable. However, if black silicon is used in combination with polycrystalline silicon wafer and cut by diamond wire, the win-win situation of cost reduction and efficiency improvement will also drive the P-type polycrystalline products to unceasingly develop towards higher efficiency.


PERC technology moving towards mono-crystalline or polycrystalline?


The actual mass production of PERC cells was started in 2014, and thereafter manufacturers in various regions expanded their capacities rapidly; its global capacity is predicted to reach 14 GW by the end of 2016, much higher than 2.5 GW in 2014. However, there has been no clear conclusion yet in the industry on whether PERC technology will take polycrystalline or mono-crystalline products as its mainstream development direction.


From the perspective of efficiency improvement, mono-crystalline PERC is superior to polycrystalline PERC, but its light-induced degradation (LID) is more serious. From the angle of cost, the additional costs of mono-crystalline and polycrystalline products by adopting PERC technology are almost the same. Therefore, which kind of PERC products a manufacturer decides to produce hinges on the price difference between cell and module produced and the market demand on the downstream system side.


Tab. 1: Price Comparison of Various Modules

Source: EnergyTrend


Regarding to the price on the system end, there is a fierce price competition between polycrystalline PERC module and conventional mono-crystalline module. Under the condition of small cost difference between both, mono-crystalline module using silicon wafer of size M2 can output 10 W more than polycrystalline PERC module and also can be sold at a relatively good price on the system end, so theoretically polycrystalline PERC products are not outstanding in cost performance.

However, because most of the big manufacturers have a high production capacity of polycrystalline products, not a few module manufacturers (e.g., Hanwha Q-cells, REC, etc.) still select to take polycrystalline PERC module as the mainstream in order to find a way out for the huge polycrystalline production capacity, which enables polycrystalline PERC to occupy a certain proportion in the PERC products.


Fig. 3: Proportion Distribution of PERC Products

Source: Data from EnergyTrend



Although the production capacity of PERC was high, there were still such problems as long PM time, the need of new machine for stability adjustment, and LID; hence the annual delivery quantity in 2015 was merely about 1 GW. Nevertheless, 290 W -- 300 W PERC products with high cost performance at a price of only US$ 0.57 -- 0.6/W were launched recently, and LID problem can be effectively controlled by the solutions put forward by equipment manufacturers like Centrotherm and Despatch. EnergyTrend expects PREC products will formally enter the mainstream market in the second half this year. But polycrystalline PREC products are not competitive enough in the aspects of cost price and efficiency improvement at present, making the diamond wire-cut polycrystalline silicon wafer and black silicon technology gain people's attention.

There is also a battle between dry texturing and wet texturing in the field of black silicon technology.


Over the past year, mono-crystalline wafer manufacturers replaced abrasive wire with diamond wire, substantially reducing the cost of wafer cutting; polycrystalline silicon wafer manufacturers also wanted to make a comeback relying on diamond wire, leading to a great upsurge in diamond wire cutting of polycrystalline silicon wafers in the market.

The diamond wire cutting of polycrystalline silicon wafers is not an innovative technology, but this method will cause over shininess of wafer, leave saw mark on the cell surface, and reduce conversion efficiency because of high reflectivity; therefore the process of surface texturing, which is widely referred to as "black silicon" technology in the industry, needs to be added during the diamond wire cutting of polycrystalline silicon wafers. Black silicon can not only solve appearance problems but form nanoscale pits and increase the amount of incident light captured, thus lowering the light reflectivity and improving the conversion efficiency of polycrystalline cell. As a result, the combination of diamond wire cutting and black silicon technology can achieve both cost reduction on the wafer side and efficiency improvement on the cell side.


Currently, black silicon technology is mainly classified into reactive ion etching (RIE) of dry texturing and metal-catalyzed chemical etching (MCCE) of wet texturing.

Judged from existing equipment, RIE technology is more recognized by the market due to its comparatively high efficiency and actual performance in mass production, but the high price of machine make many interested entrants hang back. In regard to wet MCCE, although the machine price is much lower than that of dry texturing, the existing technology has not been mature yet and tends to cause problems like uneven appearance color, low conversion efficiency, difficulty to recover liquid waste, and so on which are still insolvable at present.


Above all, there is doubt in the industry all the time about whether black silicon technology should be introduced into wafer or cell, and many manufacturers are still waiting for the answer from industrial leaders like JA Solar and Canadian Solar. For this reason, the capacity expansion of black silicon in current and next years will not be as fast as PERC in those years.


P-typemono-crystalline and polycrystalline products lead the mainstream market.


On the whole, with an aim to maintain operation ratio and obtain better profits, manufacturers will lay more stress on the demands of high efficiency market, e.g., Top Runner Program, special roof-mounted PV case, etc. To this end, in addition to the continuous improvement of processes for wafer, slurry, and screen printing, manufacturers will also continue developing PERC and black silicon technologies in an attempt to further improve conversion efficiency. The market will also become increasingly mature along with the entry of more manufacturers.


In the future, mono-crystalline products are predicted to take up increasing market share year by year since 2016 and get more gains in the market of China. The completed huge capacity of PERC will be put into production in succession since the second half this year. According to the forecast of EnergyTrend, the market share of N-type products will stay around 5% until 2018, and large rise will be unlikely to happen.


To withstand the stepped-up offensive of mono-crystalline products, polycrystalline cell manufacturers will begin to adopt black silicon technology so as to improve cell efficiency. Black silicon technology will successively bear its fruits this year, and it is expected that only about 1 GW capacity will be realized by the end this year. However, as the quality of diamond wire-cut polycrystalline silicon wafers becomes stable, black silicon products will arouse another round of hot debate in the industry from this year on.