0 BusBar technology

What is 0 BusBar technology?

This is a new design for solar cell power conducting design. Instead of stripes as in MBB or SMBB technology, ZBB has very tiny wires for transferring energy into cells and between cells. The simple way explanation for ZBB is the smallest interconnection at the solar cell that is better for the performance and strength of cell.   

0BB Cells Interconnection

1. First Method SmartWire Connection Technology
   The key element of SmartWire is the copper wire composite film, which mainly consists of an electrically
   insulating optically transparent film, an adhesive layer on the film surface, and multiple parallel coppers
   wires (tabbing ribbons) coated and embedded within the adhesive layer. The copper wires are bonded to
   the surface of the film using the adhesive layer, and their surface protruded with a low-melting-point
   alloy coating from the adhesive layer.
   The alloying of the film and grid is achieved through lamination. The copper wire composite film is
   connected to the solar cell, serially connecting the solar cells. It is then overlapped with the encapsulation
   film, backsheet, or glass, and a stable electrical connection is formed between the tabbing ribbons and
   the grid during the heating lamination process.
   The copper wire composite film is laminated on the surfaces of adjacent solar cells to form a series
   connection. Compared to conventional solar cell packaging processes, the interconnection of the main
   grid solar cells is achieved by using a new type of stringer machine to lay the copper wire composite film
   on the front and back surfaces of two cells, enabling the series connection of adjacent cells. After the
   cells are interconnected, they are arranged and stacked, and under certain lamination temperatures and
   pressure, the copper wires and the solar cell grids are pressed together to form an ohmic contact.
2. Second Method: Dispension
   (1) Dispensing: applying adhesive in the form of multiple adhesive droplets on the surface of each solar
   cell; (2) Tabbing: evenly spacing multiple tabbing ribbons perpendicular to the grid lines on the surface of
   each solar cell; (3) Fixing: using UV light to cure the adhesive and bond each tabbing ribbon to its
   a corresponding solar cell, ensuring direct contact between each tabbing ribbon and the surface grid lines;
   (4) Lamination: heating and laminating the solar cell assembly to form alloy connections between the
   tabbing ribbons and the grid lines.
   The main difference between this process and traditional stringing lies in (1) Dispensing: using adhesive
   droplets to bond the tabbing ribbons to the solar cells, enabling both series connection of multiple solar
   cells and immobilization of the tabbing ribbons on the cells for subsequent module encapsulation; (2)
   Alloying through lamination: achieving ohmic contact through the lamination process.
   The advantages of this approach include simple equipment and high stability, while the disadvantages
   include potential shadows during EL testing under the tabbing ribbons and insufficient bonding strength
   between the tabbing ribbons and the solar cells.
3. Third Method: soldering dispensation
   (1) Soldering: using infrared heating to melt the surface of the solder ribbon, creating a preliminary
   connection with the surface and grid lines of the solar cell; (2) Dispensing: applying adhesive droplets at
   specified locations on the soldered solar cell-ribbon assembly. The number of adhesive droplets should be carefully controlled to balance process complexity and bonding strength requirements. Typically, 3-8
   rows of adhesive droplets are applied based on the shadowing area and mechanical performance needs;
   (3) Curing: solidifying the adhesive droplets on the front side of the soldered cell string. The cell string is
   then transferred to the next station, flipped under controlled temperature conditions, and adhesive
   droplets are applied and cured on the backside of the cell string, forming the final cell string.
   Compared to the adhesive bonding approach, the solder adhesive bonding method involves a
   preliminary soldering step followed by an adhesive application for reinforcement. The initial connection
   between the solder ribbon and the grid lines is established through methods like infrared heating, and
   then adhesive is applied and cured to further enhance the stability of the solder ribbon-cell connection.
   The advantages of this approach include strong bonding between the solder ribbon and the solar cell,
   minimizing the risk of ribbon detachment. However, there is a risk of grid breakage during the soldering
   process, and the dispensing process requires high precision, making it a challenging and relatively slow
   process