EU PVSEC: Soaring silver prices behind efficiency tradeoff, new paste tech

The high cost of silver is causing some manufacturers to make a tradeoff between paste consumption and efficiency. It’s also behind a spate of new product introductions from silver paste suppliers.

The high cost of silver is causing some manufacturers to make a tradeoff between paste consumption and efficiency. It?s also behind a spate of new product introductions from silver paste suppliers.

Silver, which has soared in price in recent months, now accounts for as much as 10% of the total bill of materials. ?It?s starting to reach a level where it will have an impact on the overall cost of a photovoltaic module,? said Martin Green of the University of New South Wales during the plenary session. ?That portion is likely to keep growing. It will reach $50/ounce this year and some have projected even as high as $400/ounce by 2015. ? Green said he thought the large demand from the PV industry, which is several tons per month, was largely responsible for the steep increase (PV accounts for roughly 11% of the world?s silver supply consumption, according to Bloomberg online).

To offset these higher costs, some manufacturers are tweaking their new double-print screen printing process: A 30% reduction in paste consumption can still yield a 2% improvement in efficiency with the new process, instead of the 3-4% efficiency gain, according to one industry source.

Manufacturers are also working with silver paste suppliers to reduce the amount of silver in the paste, and explore alternatives. At EU PVSEC, new silver pastes were introduced by Ferro, DuPont and Heraeus. Ferro Electronic Materials, for example, introduce NS 3130 and NS 3131 which provide up to 20% savings on material usage and 0.40% absolute gains in electrical efficiency. They are capable of printing narrow grid lines 65 microns wide with a high aspect ratio (up to 0.3), and can contact up to 100 Ohm/sq emitters. “These new products lower the cost of ownership to make solar energy more cost-competitive,” said Roupen Keusseyan, research manager, solar materials for Ferro Electronic Materials. ?NS 3130 and NS 3131 reduce costs while providing high efficiency, durability, and manufacturability.? 

Prior to the show, DuPont Microcircuit Materials (MCM) announced that it recently added two key accounts, Sunways AG and Heckert Solar AG, to the list of manufacturers using DuPont Solamet PV17x photovoltaic metallization pastes to produce higher efficiency solar cells and modules.  DuPont says that because Solamet PV17x series metallizations also enable 10 percent lower material consumption, they achieve results more cost effectively. 

At EU PVSEC, Heraeus is highlighting the SOL205 low silver content back-side paste, and introduced the SOL500 Series of metallization pastes formulated for low temperature processing. Heraeus? SOL530, SOL540 and SOL550 all possess faster cure times, higher efficiencies and greater adhesion. Heraeus? SOL530 is designed for organic photovoltaic cells. SOL530 provides organic PV cell manufacturers with the advantage of printing over a large area with minimal pinholes. Heraeus? SOL540 was formulated for front-side and back-side busbars on advanced cell designs such as PERL solar cells, providing demonstrated adhesion strengths greater than 3 Newtons. Heraeus? SOL550 was developed for applications such as HIT cells possessing low resistivity with a high aspect ratio.

In related news, DuPont recently filed a lawsuit against Heraeus Holding GmbH and Heraeus Materials Technology, LLC for allegedly infringing a DuPont patent related to its front-side metallization paste materials used in solar cell technology. In its federal court filing, DuPont alleged that Heraeus has infringed DuPont U.S. Patent No. 7,767,254 B2, by manufacturing solar cells and inducing its customers to manufacture solar cells, using Heraeus H94XX series and H92XX series front-side silver pastes.


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