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 200 ℃
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.
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