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The 9th edition of the Workshop on Metallization and Interconnection for Crystalline Silicon Solar Cells was held as an online event but nevertheless reached the workshop goals of knowledge sharing and networking. The technology of screen-printed contacts of high temperature pastes continues its fast progress enabled by better understanding of the phenomena taking place during printing and firing, and progress in materials. Great improvements were also achieved in low temperature paste printing and plated metallization. In the field of interconnection, progress was reported on multiwire approaches, electrically conductive adhesives and on foil-based approaches. Common to many contributions at the workshop was the use of advanced laser processes to improve performance or throughput.

The 6 th Metallization Workshop took place in Constance, Germany on 2 and 3 May 2016. At the workshop the latest progress in the understanding and application of metallization and interconnection was presented. Screen printed metallization continues to dominate. Material and application technologies are constantly further improved, with sub-40 μm fingers with high cell performance and low Ag consumption demonstrated. Cu plating technology is further perfected in anticipation of large scale industrial implementation, with improvements on adhesion and long term reliability. In interconnection, alternatives to the traditional ribbon soldering technology are proposed. Among them, the multi-wires interconnection schemes are shown to have a dramatic impact on metallization design and technology.

This article gives a summary of the 8th Metallization and Interconnection workshop and attempts to place each contribution in the appropriate context. The field of metallization and interconnection continues to progress at a very fast pace. Several printing techniques can now achieve linewidths below 20 µm. Screen printing is more than ever the dominating metallization technology in the industry, with finger widths of 45 µm in routine mass production and values below 20 µm in the lab. Plating technology is also being improved, particularly through the development of lower cost patterning techniques. Interconnection technology is changing fast, with introduction in mass production of multiwire and shingled cells technologies. New models and characterization techniques are being introduced to study and understand in detail these new interconnection technologies.

This paper summarizes the trends in metallization and interconnection technology in the eyes of the participants of the 8th Metallization and Interconnection Workshop. Participants were asked in a questionnaire to share their view on the future development of metallization technology, the kind of metal used for front side metallization and the future development of interconnection technology. The continuous improvement of the screen-printing technology is reflected in the high expected percentage share decreasing from 88% in three years to still 70% in ten years. The dominating front side metal in the view of the participants will be silver with an expected percentage share of nearly 70% in 2029. Regarding interconnection technologies, the experts of the workshop expect new technologies to gain significant technology shares faster. Whereas in three years soldering on busbars is expected to dominate with a percentage share of 71% it will drop in ten years to 35% in the eyes of the participants. Multiwire and shingling technologies are seen to have the highest potential with expected percentage shares of 33% (multiwire) and 16% (shingling) in ten years.

For the seventh-time experts and specialists from all over the world discussed the latest status, trends and new directions in the field of metallization and interconnection for crystalline silicon solar cells on October 23rd and 24th, 2017, in Constance, Germany. The first Workshop on Metallization for Crystalline Silicon Solar Cells was held in 2008 in Utrecht, The Netherlands to provide a forum for metallization specialists and was followed by Workshops in Constance, Germany, 2010; in Charleroi, Belgium, 2011; and again, in Constance in 2013, 2014 and 2016. In 2016, the Workshop was renamed as Workshop on Metallization and Interconnection for Crystalline Silicon Solar Cells to reflect the growing importance of interconnection. This year, about 151 participants from 17 countries all over the world came to discuss the results of 35 presentations and participate to panel discussions. The presentations are available on www.metallizationworkshop.info as pdf documents. These proceedings contain peer-reviewed papers relating to some of the workshop contributions. During the Workshop, the participants filled in a questionnaire about their views on the future of metallization and interconnection. In these proceedings, we also show the results of the 7th edition questionnaire plotted together with results from previous editions and we discuss general trends.

As in the previous workshop editions the participants of the 7th Metallization and Interconnection Workshop were asked to share their view on the future of metallization and interconnection. In this paper results of the survey are summarized. The trend of the past years is reflected. Established technologies like screen-printing or soldering on busbars are seen to dominate for the next years.