PV welding with high extensibility of for preventing weld failure in the bus and the interconnection between the welding zone is very important, due to the change of the temperature oscillations in the process of solar panels run extending / tension may occur such a failure. A day in the life of the solar panels process continuous, sometimes a particularly intense temperature oscillation solder joints tested during the life of the solar panels (an average of 25 years).
Two parameters critical of the most PV welding with manufacturers curvature and yield strength. Many PV welding with manufacturers, while difficult to achieve a high level welding with softness and guarantee its straightness. Get enough softness and low camber possible means to win and lose the difference between the supply contract. Manufacturers must therefore strive to improve their rolling, annealing, of tinned and materials processing technology, to meet the increasing performance requirements.
Key parameters: yield strength
The coefficient of thermal expansion of copper and silicon, the thermal expansion coefficient is different. Interconnect solder with solder about
silicon cells. Series welding cooling will produce bending. This may lead to
destruction of the silicon crystal. Interconnect welding with low yield
strength to reduce stress within the silicon cells in series welding, thus
reducing scrap rates.
Using increasingly thin solar panel for welding with a lower yield strength (Rp0.2%). Just a few years ago, the 300 micron thick solar cell is also in general use. They can withstand the stress of the yield strength <120MPa welding zone. Now commonly used in the battery of 160-180 microns thick, and its mating weld with yield strength <70MPa-<80MPa. The average thickness of the battery seems to continue to look downward, to weld with manufacturers to bring further pressure to the yield strength should be reduced to 65MPa.
In order to reduce PV yield strength of the weld with the manufacturers should be looking for ways to improve in the following areas:
● Select the appropriate input copper material
● Select the correct annealing and rolling technology
● ensure accurate soldering tinned production line transport system with
● good tinned production lines in volume online actinomycetes and precise winding.
Should check their string welder the actinomycetes system, solar panel manufacturers want to reduce the stress on the battery after a series welding, to avoid welding with the hardening process of actinomycetes produce curvature. Some solar panel manufacturers have taken another solar panel design, each battery has three or even four smaller ribbons (instead of two), to further reduce the stress on the battery in the string after welding.
Key parameters: bend
Low camber placed for ensuring a straight line of the welding zone of the interconnection string welding process is very important. As the the series welding speed increases, the production of solar panels has been fully automated. Interconnect welding process used with curved large, high-yield the automatic string welder plagued by unnecessary downtime. The large curved ribbons even cause bad solder joint or string welder on rejection rate increase. The current goal pursued bend usually <
5mm / m. The tighter bend degree requirements
trends show that the solar
cell in the future, manufacturers may be required
to < 3mm / m bend.
To make the minimum bend PV welding with manufacturers have to seek to improve in the following areas:
● spool winding layer precision, which requires precision mechanics structure and precise process control;
● consistent welding with quality, especially smaller overburden thickness tolerance;
● Select the appropriate size spools.
The manufacturer very clearly the limits of the spool on the edge of the smallest possible curvature of the spool at the edge welding with changing direction during placement. Spool on the smallest possible curvature depends on the diameter of the cylinder size and spools of ribbons.
However, in order to improve the welding before welding with the placement of the solar panel manufacturer or series welder suppliers themselves can check the system of the string welder Actinobacillus possible improvements. Increase the bobbin size also helps to reduce the curvature generated by the edge of the bobbin.
PV welding with of production: PlasmaPREPLATE tinned and traditional tinned comparison
The traditional copper, tinned copper wire through a molten tin / solder bath, and then in the cooling tower vertical wipe and cooling the copper after plating. Intermetallic bond only online surface clean and proper activation can be achieved. Acid wash or soak is used for the surface prior to activation of a conventional method of cleaning the copper surface, which is soaked flux. Dip flux is dirty and environmentally unfriendly process, the operator can also be detrimental.