Ahead of DuPont speaking at the PV CellTech 2018 meeting in Penang, Malaysia on 13-14 March 2018, PV Tech spoke with Guangyao Jin, Chief Scientist at DuPont Photovoltaic & Advanced Materials, on the company’s views on PV cell manufacturing.

DuPont has been a key part of solar cell manufacturing, as the industry moved to 100GW of solar cell production in 2018. What have been the main changes in silver paste supply over the past decade, and how has this enabled cell producers?

The PV industry goal is always pursuing lower CoO (cost of ownership) in cell manufacturing side, so the paste technology as the core driving force has kept leading the solar cell manufacturing toward higher efficiency with less materials consumption. To achieve higher cell efficiency, finer line printing with better contact resistivity and metal contact recombination control is the key. 

DuPont is one of the leading innovator in advancing cell technologies, for the past 12 years, we continue to drive cell efficiency gain 0.1% ~0.2% by each new generation product that’s about 25% increase in solar panel power and up to now reduce the laydown by 70% in total.

So actually, even the installation capacity is keep growing until today at 100GW, the paste consumption is off set by the new paste technology adoption. 

What can we expect with silver consumption in the next few years?

Metallization materials consumption in terms of mg/Watt will continue to decrease with the cell efficiency is keep increasing when the industry moving to finer line screens and multi busbars. 

DuPont has been leading the development of metallization technology to enable advanced cell technology, such as LDE, PERC, N-type and bi-facial and we will continue to focus on material innovation to provide metallization solutions that help to reduce cost of ownership in terms of cell manufacturing. However, it also dependent on the improvements and advances in fine line screen technology as well as the development of multi busbar module technology and the maturity in mass production.

How have pastes been improved, enabling cell efficiencies to keep increasing each year?

DuPont is leading and driving the screen printing technology towards finer lines, with overcoming various challenges, such as further improving the contact resistivity as well as the grid line resistance.

Nowadays, when more advanced solar cell structures like PERC/ N-PERT get into large scale production, we also have to further minimize the contact recombination at the metal and silicon contact interface, because it starts to hurdle the further efficiency improvement for cell structures with higher open circuit voltage.

Besides the above universal key points to looking after, DuPont has also build up the capability of customizations of various formulation to meet the diversified cell structure, manufacturing process and printing , such as DWS, Selective doping, Contact passivation, Multi-busbars and etc.

How have the new high-efficiency concepts placed demands on R&D from DuPont and why has this been important to support the industry?

DuPont is leading the pace of innovation in solar industry by continually advancing the cell efficiencies by customize and improving our paste products. We continue to bring new generation of products to the market every 3~6 months. 

We also closely work with different research institutes worldwide and through intensive customer collaborations to develop materials for various new applications like N-type/Yingli, Jolywood and LONGi, IBC and HJT cell technologies. We also look into new module technologies, for example shingled cells, as we develop interconnect metallization for novel module assembly. 

What can we expect to hear from DuPont, at the PV CellTech meeting in Penang on 13-14 March 2018?

We will introduce an overview of our metallization technology to boost cell efficiency and help to lower LCOE. These will cover both P type and N type technologies. 

For P type cells, we will introduce the latest 'Solamet' front side silver, PV21A. With proprietary design that delivers better contact performance and high aspect ratios, Solamet PV21A metallization paste enables excellent fine line printability that can drive cell efficiency enhancement >0.1 percent and maintains high throughput in mass production. The optimal balance of good adhesion and low laydown leads to low cost of ownership for cell manufacturers. 

The Solamet PV21A product family is designed to fulfill all mainstream cell technology, it also includes product series for advanced printing such as double printing, dual print and mesh cross free screen printing. Industry-leading performance is proven on a variety of substrates such as DWS (Dimond Wire Saw) wafer and black silicon.

For N type, we will introduce our new generation products that enables 0.2% efficiency gain.