Solar cells will also enter the copper wiring era

It was found through observation that the silver wiring in the vertical and horizontal directions was distributed on the surface of the crystalline silicon solar cell. At present, around the wiring materials of solar cells, various companies have launched fierce technological development competition.

Now, the solar cell surface wiring is formed with silver paste. Due to the recent surge in the price of silver, the proportion of silver paste in solar cell manufacturing costs has continuously increased. A solar battery company stated that “silver paste accounts for 60% of the material cost of the battery cell process.” Moreover, if the output of solar cell units increases in the future, the use of silver in the solar cell industry will also increase. It is estimated that the amount of use will be equivalent to the total output of silver.

Therefore, at the "EUPVSEC" of the International Society for Solar Cells held in October 2013, reducing silver consumption has become a topic. For example, Canadian Solar has succeeded in reducing the amount of silver on the surface of new generation battery cells by 15%.

However, there is also a limit to the reduction in silver usage. Therefore, as a countermeasure to the next step, the industry is exploring a scheme of changing silver wiring to copper wiring. For example, Kaneka has developed monocrystalline silicon solar cells using copper wiring and heterojunctions. The copper wiring is formed by electroplating. In the case of Panasonic's "HIT solar cell," the use of a heterojunction results in the problem that the resistance of the silver wiring increases because the sintering temperature of the silver paste cannot be sufficiently increased. Therefore, if the silver paste wiring can be changed to copper plating wiring, not only the cost can be reduced, but also the wiring resistance can be reduced. As a result, the output power of the battery will increase and the conversion efficiency will increase.

As long as conditions are met, solar cells may quickly transition to copper wiring that helps reduce costs and improve features. Looking back, when the author was still a semiconductor technician, in order to reduce the wiring resistance, the semiconductor field also transitioned from aluminum wiring to copper wiring. I still remember the situation: There was a company that announced its intention to adopt copper wiring as soon as possible, and then the concept of “aluminum wiring technology is out of date” began to enter the hearts of people, and companies quickly followed suit. I suspect that the same situation will occur in the field of solar cells.