Multi wire stringer for higher module power and silver savings

In a unique and innovative process, the Multi Busbar Connector connects solar cells to strings with 12 round wires and 20 soldering pads per wire at high-speed. The aesthetic cell design turns modules into a premium product with 6 – 9 W more power output.

Shorter and narrower grid fingers result in a higher fill factor and a higher current – at lower costs: Up to 25 % silver can be saved when screenprinting the cells. Moreover, light hitting the round copper wires is reflected back onto the cell. This very efficient light recycling contributes to the minimized cell-to-module (CTM) loss. Modules with 60 cells show a CTM loss of less than 4.5 % when using SCHMID’s reliable multi busbar connection solution.

The solar cells are processed “sunny side up”. The wires with a core diameter of 360 µm and a 15 µm SnPbAg coating are covered with flux inside the machine. The front-to-back soldering of the wires to the cells is performed on a preheated chuck. The wires are held by special parallel grippers. A motion axis system together with a high precision imaging system ensures exact cell placement with an accuracy of 0.05 mm. Thus, a precise overlap of the small wires and the metallization pattern of the cells is guaranteed, even with minimum solder pad sizes.

Existing module production lines are easy to be upgraded: The Multi Busbar Connector harmonizes with subsequent lamination processes and uses proven contact-free infrared soldering technology which is compatible with all cell designs.

• Cutting edge stringing process for high efficiency premium modules
• 6-9 W more module power output due to less shading, lower series resistance and improved light harvest
• Compatible with standard monocrystalline and polycrystalline screen printed cells
• Less silver consumption
• Easy to integrate into existing module production lines

Dimensions (LxWxH):

• 7 x 7.5 x 2.2 m

Cell size:

• 156 x 156 mm, 156.75 x 156.75 mm

Cell thickness:

• 160 – 250 μm

Throughput:

• 1,200 cycles/h

Number of busbars:

• 12

 Breakage rate:

• < 0.5 %

 Positioning accuracy:

• ± 0.05 mm