Finnish scientists have examined a brand new soldering technique based mostly on a pattern for the ribbon tabbing of photo voltaic cells and located that it reduces the variety of cracks and injury attributable to thermal-mechanical stress within the course of. They declare that the brand new method can compete with standard soldering strategies in industrial manufacturing.
Researchers on the College of Oulu in Finland have developed a non-contact soldering method for ribbon tabbing of PV cells that may scale back thermal and mechanical stress in photo voltaic cell manufacturing, thus avoiding the danger of cracks, disconnected wiring, and hotspots.
Scientists say that assuaging thermo-mechanical stress in solder joints is troublesome, as a result of it happens between two forms of materials at excessive temperatures within the course of. “The danger of damages attributable to fatigue throughout operation will increase, resulting in excessive collection resistance losses, which creates an incredible problem to optimize the interconnection soldering course of,” they defined.
The newly developed method consists of a brand new soldering technique that should be utilized by a layer of glass. Eddy present, that’s produced by something that causes a change within the depth or course of the magnetic area in a conductor, is a non-destructive technique that may be executed on conductive supplies.
The Finnish group examined this course of on a polycrystalline silicon photo voltaic cell measuring 52 mm x 19 mm x 0.21 mm and having a silver busbar with a width of 1.8 mm in entrance and a 1.8 mm steady soldering pad on the again. Soldering operations are carried out utilizing a microscopic cowl glass slide with a dimension of 76 mm x 26 mm x 1 mm and with solder-coated copper ribbons made from fundamental lead photo voltaic alloy Sn63Pb37 at a melting temperature from 183 C to 190 C.
“Small weights (34.4 g every) are positioned on the finish of the glass plate to make sure correct contact between the ribbon and the silver busbar,” the lecturers mentioned, noting that the supply used to warmth a Energy Dice 32/900 high-frequency generator offered by the US-based CEIA, with the heating coil sustaining a distance of round 2.5 mm.
The scientists say that this setting and the induced eddy currents generate native warmth with none direct contact with the heating coil.
By a collection of exams and microstructural evaluation, they discovered that no extra cracks or injury have been seen within the cells that have been offered, apart from some samples. Additionally they confirmed {that a} longer publicity time is best to stop microcracks inside the solder joint configuration.
Picture: College of Oulu, Photo voltaic Vitality Supplies and Photo voltaic Cells, Inventive Commons License CC BY 4.0
They concluded that the brand new technique is technically and commercially possible, in addition to aggressive with conventional contact soldering methods. “Along with ribbon soldering, the proposed method was developed for use in future research to restore and restore used photo voltaic panels after failure or elevated collection resistance because of deterioration as a result of passage of time within the tabbing wire or busbar connection with out disassembling the photo voltaic module panel,” additionally they mentioned.
The soldering course of is described within the research “Eddy present soldering of photo voltaic cell ribbons underneath a layer of glass,” printed in Photo voltaic Vitality Supplies and Photo voltaic Cells.
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