Photovoltaic industry has been going through a rapid growth and relentnes price pressure over the last decade. The same is the case in the PV ribbon industry. Only PV ribbon producer that kept consistent product quality whilst maintaining low cost base and efficient production process remained competitive.
Plasmait GmbH from Austria, the leader in designing and building PV ribbon machinery, has introduced a new PV ribbon annealing and tinning line designed for high output production. The new line features a maximum production speed of 210m/min. This allows the line to produce up to 250 tonnes of PV ribbon per annum in a typical production split between interconnect and bus bar ribbons.
PV ribbon line can produce a wide range of interconnect ribbons and bus bars in a typical size range of 0.8mm to 8mm wide and 0.1 to 0.5mm thick. The ribbons are usually coated with 20 micron thick layer of solder with coating thickness tolerance of ± 3microns. The new line can produce ribbons of various yield strength, typically with Rp0,2% below 60MPa, 70MPa or 80MPa but in some special cases also below 50MPa.
Copper ribbons are paid off from a 500kg spool with finished tinned PV ribbon being spooled onto 4-10kg spools in a continuous production. The single-head, precision layer winding spooler includes an accumulator to ensure uninterrupted production during spool changeovers on the takeup side. Some producers choose to equip the line with an automatic spool changeover unit that can be integrated with the takeup unit. Multiple lines can therefore be operated with a single operator, which reduces labour cost considerably.
PV ribbon line can also be integrated with an in-line rolling mill to produce interconnect ribbons directly from round copper wire. A single or double stand rolling mill can be used for in-line operation subject to required size and tolerance of the finished ribbon.
Unlike traditional tinning process, plasma tinning line operates without chemical cleaning and fluxing whilst rolling runs without cooling agents. This makes the whole production dry and environmentally friendly.
Flux-free plasma tinning process avoids contamination of tin bath with flux, which makes a big difference in the cost tin waste. Average annual saving in terms of tin waste alone is as high as 100 thousand euros per line when compared to the traditional flux based tinning process. This does not take into account the savings a PV ribbon producer yields from reduced scrap rates. Continuous production of 500kg combined with average 95% uptimes and high level of automation allow PV ribbon producers to reduce their labour costs and scrap rates whilst improving production consistency and product quality. The new line features also lowest energy use and maintenance cost per kg of finished material. This combined allows the new PV ribbon line to claim by far the lowest cost of PV ribbon production overall.
The new line can be equipped with specially designed wiping system for round wires for production of a new type round PV ribbons that have recently been introduced in solar panel manufacturing.
Figure: New High-Speed PV Ribbon Line by Plasmait GmbH