PV ribbon is an important part of every mainstream solar panel, which is used to interconnect solar cells and provide connection with junction box. PV ribbon is tinned copper PV ribbon, with width of 1-6mm, thickness of 0.08-0.5mm and flux coating of 10-30 μ m.

There are two forms of application of PV ribbonin photovoltaic modules: interconnection solar wire  or bus bar andPV bus bar. Both are needed in a typical silicon solar cell. The interconnection PV ribbon is directly welded on the silicon crystal to connect the solar cells in the solar panel with each other. The interconnection PV ribbon carries the current generated by the solar cell to the PV bus. PV bus is a hot-dip tinned copper conductor installed around the solar panel. The PV bus connects the interconnection PV ribbon to the junction box. Thin film solar panels generally only need bus bars.

The  PVribbonis the key component in the solar panel, which is an important factor to improve the efficiency and durability of the solar panel. The high efficiency and durability of solar panels can only be achieved by using high-quality PV ribbons properly installed in solar panels. High quality PV ribbon can also improve the production efficiency of solar panels and reduce the scrap rate. The quality of PV ribbon and its welding to solar cell are important factors to ensure the efficiency and durability of solar panel.

1. At present, the PV ribbon in the market is mainly divided into silver containing and silver free. In addition to being expensive, the silver containing welding belt has its own advantages:

1) Increase the metallurgical bond between solder and the metal to be welded. The mechanical strength and conductivity will be better after welding.

2) After adding silver, the melting point of ternary alloy is lower than that of binary alloy, and its weldability and fluidity are improved

3) The resistivity will be reduced and the high temperature resistance will be improved.

2. The resistance of the PV ribbon is mainly determined by the size and specification of the PV ribbon itself and the material of the copper substrate. The composition of the tin coating on the surface will not significantly affect the resistance of the welding PV ribbon. Increasing the width or thickness of the PV ribbon can reduce the resistance of the PV ribbon. This improvement can play the same role in the traditional welding method, or in the new conductive silver glue or conductive tape connection and other low-temperature connection methods. However, the width of the PV ribbon wider than the front electrode will block the incident light and cause current loss. It is recommended to use thick welding tape without affecting the fragment rate.

3. The part of solar cell covered by welding tape can't absorb sunlight. Some welding tape companies have introduced reflective welding tape. The front side of welding tape is silver plated and rolled out with longitudinal groove structure. This structure can reflect the light incident on the welding tape to the inner surface of the glass layer of the module at a certain angle, and project it back to the battery surface after full reflection on the glass air interface. The captured light can generate additional power for the module, which can theoretically improve the efficiency of the module by about 2%.

4. Key quality parameters of PV ribbon

The performance index of PV ribbon is very important in itself. The type and purity of copper determine the conductivity of the material and the maximum softness of the welding PV ribbon. Flux composition, coating thickness and coating composition affect the quality of solder joints, thus affecting the durability of solar panels.

The high elongation of PV ribbon is very important to prevent the solder joint failure between busbar and interconnection welding PV ribbon, which may occur due to the extension / tension caused by temperature oscillation during the operation of solar panel. During the service life of the solar panel, the continuous and sometimes extremely intense temperature oscillation makes the solder joints stand the test during the service life of the solar panel (25 years on average).