EoW November 2013

Technical article

PV ribbon: Overview of product specifications and comparison of production processes By Igor Rogelj, Peter Ziger and Primoz Eiselt, Plasmait GmbH, Lebring, Austria

Abstract PV ribbon is an essential component in every mainstream solar panel and is used to interconnect solar cells and provide connection to the junction box. PV ribbon is tinned copper ribbon between 1mm-6mm wide and 0.08mm-0.5mm thick, with a 10 micron-30 micron thick solder coat. The quality of PV ribbon and its soldering to the solar cells is essential to ensure panel efficiency and durability. This article scans the market dynamics of PV ribbon manufacturing and outlines PV ribbon product specifications commonly required by the panel manufacturers. These include properties such as material compositions, dimension ranges, straightness, solder coat thickness, mechanical characteristics and others. The traditional tinning process is compared to the new chemical-free plasma assisted tinning process, which has been widely adopted in the West and increasingly in Asia as well. The two production processes are compared in terms of output, productivity, efficiency, process control and environmental impact. PV ribbon PV ribbon is a hot dip tinned copper conductor used in photovoltaic solar panels. There are two types of PV ribbon: The interconnect or tabbing ribbon and PV bus bar, both needed in a typical silicon solar cell. Thin film panels usually require only bus bar. The interconnect ribbon is soldered directly onto silicon crystal to interconnect solar cells in a solar panel. The interconnect ribbon carries the current generated in solar cells to the PV bus bar.

▲ ▲ Figure 1 : Interconnect ribbon produced on the PlasmaPREPLATE Tinning line and wound on the spool as a finished product ready for stringing

This results in ever changing PV ribbon specifications. PV ribbon suppliers are also under constant price pressure, which is led by fast declines in solar panel prices. PV ribbon is a key component in the solar panel and is an important factor driving panel efficiency and durability. High efficiency and durability of the solar panel can only be achieved with a good quality PV ribbon that has been properly installed into the solar panel. Good quality PV ribbon can also improve panel production efficiency and reduces associated scrap rates. To ensure high productivity of the stringing process a good quality, straight,

PV bus bar is a hot dip tinned copper conductor installed around the perimeter of the solar panels. PV bus bar connects interconnect ribbons to the junction box.

PV ribbon market dynamics

PV ribbon manufacturing is a growing, dynamic and fragmented part of the PV industry. There are many different types of solar panels and solar cells, which require different types of PV ribbons. Solar panel and cell designs are constantly changing driven by rapid innovation in the PV industry.

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November 2013