Silver Paste

Developed by a U.S.-based start-up, the new manufacturing process is claimed to reduce silver consumption and improve solar module performance by up to 3 W. It consists of connecting sub-cells in series within a single cell in order to increase the device voltage and without requiring cells to be physically broken and rewired.

Scientists at Germany’s Fraunhofer ISE developed a model to simulate different setups for screen printing in solar cell metallization. The model provides a comparable ‘screen utility index’ value that can predict the usefulness of different architectures in the printing equipment in relation to the properties of a given silver paste. The approach, says Fraunhofer, will assist the PV industry in reducing the amounts of silver needed in silicon cell manufacturing.

The share of silver in the total cost of PV modules has increased by around 5% in recent months, according to US analyst Matthew Watson. He told pv magazine that silver prices are set to rise, adding that the metal will eventually account for an even larger percentage of overall module costs.

Increasing prices may prompt module manufacturers to find alternatives, or at least reduce silver use in solar cell metallization, according to a recent study. Researcher Samuele Lo Piano, however, told pv magazine silver availability does not represent an issue for large scale PV. Copper-nickel alloys may offer an alternative, he added, but there could be a long wait for them to be viable.

Silver demand for PV production worldwide is forecast to grow to 105 million ounces this year, as overall demand hits an eight-year high. Prices for the precious metal could reach a seven-year high of $30.00 per ounce this year but, according to the Silver Institute, this level is still far away from any critical threshold that would make silver supply for the solar industry problematic.

Scientists led by staff from Germany’s Fraunhofer ISE have demonstrated a new laser printing process in pilot production, which could replace silver paste and screen printing in solar cell manufacturing. The system is said to offer much more flexibility in the layout of contact fingers on the cell surface and a wider choice of metallization materials.

Using an innovative high-speed video setup, scientists in Germany were able to observe the screen-printing process used in solar cell metallization, on a time scale of less than 50 milliseconds. Insights into the paste’s behavior and the mechanisms at work during screen printing will improve the process and the formulation of the silver paste it relies on.

Silver prices reached their highest levels this week since 2016. But Michael DiRienzo, executive director of The Silver Institute, says prices are still not high enough to complicate silver supplies for the PV industry.

The SOL 7 series comprises five products for Perc, Topcon and heterojunction devices.

A Silver Institute study says demand for the precious metal for solar manufacturing accounted for 11% of global consumption last year but reduced solar generation capacity up to 2023 will eat into that figure and ‘thrifting’ technological advances will kick in after that point.