Professor Sun Yun, Nankai University reminder: SI: environmental issues cannot be ignored

Polaris solar PV net news: in recent years, as countries around the world consistently in non-crystalline silicon solar energy utilization research and development in the field of power, low cost, large areas of CIGS (Copper-Indium-Gallium-selenium) can already see results. Although its market share is less than 15% of total PV market, but with the CIGS technology breakthrough, CIGS solar cells is becoming more alternative to crystalline silicon.

Professor Sun Yun, Nankai University

Reporters: Professor Sun, Hello! Existing pollution in the production process of crystalline silicon cells which link? The current situation? If a technology and equipment are effectively addressed?

Sun Yun: I feel main pollution in production Silicon material this block, because quartz sand made Silicon material of process in the, needs with to four chloride silicon, slightly processing improper, this liquid on easy seeping, pollution around plant, certainly, this problem can in configuration related supporting facilities and management strictly of situation Xia be solution, but manufacturers often will in reduced production cost this a interests drive Xia and “selective” ignored; also, crystal silicon battery production process in the not only high pollution, and high-energy, Silicon of melting point is 1400 degrees, From silica to Silicon, ingots, requires a trip to the purification, need a lot of processes in the Middle, so we usually mean high pollution and high energy consumption is above both.

Reporter: amorphous silicon solar cell production collective pollution is still there? Is the industry’s problems, or the problems of enterprises themselves?

Sun Yun: I don’t think crystal silicon solar cell production is polluting the whole industrial chain, component production, for example, no pollution, diffusion process of acid and alkali cleaning, corrosion, grooving inside will use some pH stuff, pollution is not very big, but still better than films are seriously polluted. Thin-film module cleaning can be carried out on the glass, is often used in organic cleaning agent, not only there is no pollution of acid-base and vacuum coating, so films virtually no pollution in this area.

I think the pollution is their own problem because production pollution no pollution, mainly to see the alignment is not complete supporting facilities, supporting complete implementation, together with strict management, even though production costs may be slightly higher, but pollution problems can be avoided.

Reporter: are you as a leader, your specialty is the study of CIGS thin-film batteries. In your opinion, the technology direction for pollution problems?

Sun Yun: so far, we haven’t found CIGS has serious pollution problems. The past, part of CIGS will use highly toxic hydrogen selenide gas, but due to the treatment unit, emissions should not be a problem. In addition, most of the CIGS cells with a layer of cadmium chloride, about 50 nanometers, the liquid which contains heavy metals, compared to CdTe is still far, cadmium in cadmium telluride 5-8 micron, but sealed should not cause pollution, pollution, Germany and the United States would not be produced.

At present, a number of manufacturers have been using cadmium-free processes, Japan SolarFrontier is currently producing Copper-Indium-Gallium-selenium element, this element does not contain cadmium, which fully reflects this aspect of pollution can be overcome.

Reporter: internally the CIGS manufacturers now produce products containing cadmium which ingredients?

Sun Yun: at present, the CIGS manufacturers such as, place des Vosges and other products should be produced containing cadmium, seen in the domestic similar reports of cadmium free products. We have found, CIGS products containing cadmium conversion rate is relatively high, a higher conversion rate than cadmium free.

Reporter: with amorphous silicon solar cell (module), what are the main advantages of the CIGS thin film solar cell? What are the advantages of better marketing?

Sun Yun: from battery itself for, advantages also is compared more of, first, cost low, we said of cost are is concept sex of cost, now actually also no reached, because it now also belongs to technology hatch period; second, energy low, Copper Indium Gallium se products on in glass, and plastic or stainless steel Shang for processing, whole film plus in together only 3-4 micron, crystal silicon is needs 200 Micron; again, crystal silicon not only material price also expensive, and loss serious, slice process in the saw sewing faded down of Silicon material or can up one-third , Which can no longer be recycled, because many of these powders containing metal components, it is difficult to purify, moreover, need 1400 degree to Silicon ingot, wafer diffusion do then need 900 degrees, energy consumption is considerable. And CIGS whole industry chain in a workshop within on can completed, needs of glass also on 2-3 Micron, cost can controlled, and, production process by needed temperature Supreme only 500-600 degrees; third, conversion efficiency high, currently, CIGS of laboratory conversion efficiency has over crystal silicon, as SolarFrontier has reached 20.9%, and market Shang polysilicon mainstream conversion efficiency for 20.4%-20.5%, produced line Shang, CIGS component efficiency has reached 13%-14% , Even is 14%-15%, and market Shang Silicon efficiency for 15%-16%, more crystal silicon also on 14%-15%; also, CIGS absorption very wide, it can in too Sun Xia 350 Nano near purple outside to 1100 Nano all can has reaction, and crystal silicon in Longwave part is do not to, only reached 900-1000 Nano, non-crystal silicon compared to more weak, only can reached 700-800 Nano, visible CIGS of weak light response very good; last, is most important of point, Is a higher power generation capacity, according to the experimental data, CIGS higher annual output than SI 10%.

In my opinion, market application, is its annual output capacity, BIPV and that it can do, in addition, the CIGS can also make flexible battery.

Reporter: in your mind CIGS thin-film battery technology improved in the future and how much, there is no technology roadmap?

Sun Yun: CIGS industrialization of great technical difficulty, is to a large extent the device, because the equipment is more complex than crystalline silicon, is bound to increase its cost. Equipment, primarily production technology is not yet mature enough, but there is still a large room for manoeuvre in this respect, such as guaranteeing the uniformity of the film, product yield, process stability, and reducing the fault rate of the equipment, production rates, and so on, this column enables you to reduce costs.

I think the core of industrialization of CIGS technology has broken out, because it can be continuous production cells, mainly behind is how to reduce costs and improve maturity issues.

Reporter: what do you think of CIGS thin film solar cells and amorphous silicon solar cell application?

Sun Yun: applications, I think both have their market reach, low Silicon cost and suitable for large-scale building power plants, Copper-Indium-Gallium-selenium can also be, but high cost and curtain wall can be done. At present, SI recession rate this question is very prominent on the market due to mass production, the pursuit of low-cost, product quality much worse than before, and I think the next year or two will appear on the domestic market because of quality problems, such as the recession caused a series of claims, when the time comes people will find Copper-Indium-Gallium-selenium stable performance and low decline rates and other advantages.

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