First, the impact of PV ribbons on components
PV ribbons are an important part of every mainstream solar panel used to interconnect solar cells and provide connection to junction boxes. PV ribbons are tinned copper ribbons, width 1-6mm, thickness 0.08-0.5mm, with 10 - 30μm thick flux coating.
PV ribbons are applied to photovoltaic modules in two forms: interconnect strips or busbars and PV busbars. Both are required in typical silicon solar cells. Interconnect strips are soldered directly to silicon crystals The solar cells in the interconnect are interconnected. The interconnecting tape brings the current generated by the solar cell to the PV busbar. The PV bus is a hot-dip tinned copper conductor mounted around the perimeter of the solar panel. The PV busbar connects the interconnect tape to the Junction box. Thin film solar panels generally require only busbars.
PV strips in solar panels are key components, which are important factors for improving the efficiency and durability of solar panels. The high efficiency and durability of solar panels can only be achieved with high-quality PV ribbons that are properly installed in solar panels. It can also increase the production efficiency of solar panels and reduce scrap rate. The quality of PV ribbons and their welding on solar cells are important factors in ensuring the efficiency and durability of solar panels.
1. Currently, the ribbons in the market are mainly divided into silver-containing and silver-free ribbons. Among them, silver-containing ribbons have their own advantages in addition to being expensive:
1) Increase the metallurgical bonding between the solder and the metal to be welded. The mechanical strength and conductivity will be better after welding.
2) After the addition of silver, the melting point of the ternary alloy is lower than that of the 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 ribbon is mainly determined by the size of the 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 ribbon. Increasing the width or thickness of the ribbon will reduce the resistance of the ribbon. Improvements, whether for traditional soldering methods, or new types of low-temperature connections such as conductive silver pastes or conductive tape connections, have the same effect. However, ribbons wider than the width of the front electrode will block the incident light and cause current losses. It is recommended to use thicker tapes without affecting the fragmentation rate.
3, The solar cell is covered by the ribbon and cannot absorb the sunlight. Some ribbon companies have introduced the reflective ribbon. The front surface of the ribbon is silver-plated and rolled out of the longitudinal groove-like structure. This structure can be incident on the ribbon. The light is reflected at an angle to the inner surface of the component's glass layer and is totally reflected at the glass-air interface and then projected back onto the surface of the cell. The captured light energy allows the module to generate additional power, which can theoretically increase the module efficiency by about 2%. .
4. Key parameters of PV ribbon quality
The properties of PV ribbons are important in their own right. The type and purity of copper determine the conductivity of the material and the maximum softness of the ribbon. Flux composition, cover layer thickness and cover composition effects The quality of solder joints, thus affecting the durability of solar panels.
The high extensibility of the PV ribbon is important to prevent solder joint failure between the busbar and the interconnect ribbon, which can occur due to extension/tension caused by temperature oscillations during the operation of the solar panel. Continuous, and sometimes extremely intense, temperature oscillations throughout the service life put the solder joints under test during the lifetime of the solar panel (averaging 25 years).
The two most important parameters for most PV ribbon manufacturers are the camber and yield strength. Many PV ribbon manufacturers find it difficult to achieve a high level of ribbon flexibility while maintaining the straightness. Get enough softness. Degrees and low cambers can mean the difference between winning and losing supply contracts. Manufacturers must therefore strive to improve their rolling, annealing, tinning, and material handling technologies to meet increasing product performance requirements.
Therefore, the effect of the ribbon on the power generation of the component is not only the design material of the ribbon itself, but also the selection of the ribbon, the lamination process, and the quality control of the ribbon production. The ribbon needs to be understood from all aspects, despite industry May be more eye on the packaging material, the battery.
Second, common welding band specifications
Automatic spool with tinned copper tape
◆ Copper base: Imported refined toughness oxygen free copper/T2 copper, copper content ≥99.99%, conductivity ≥98%
◆ Copper base resistivity: Oxygen-free copper ≤ 0.0165Ωmm2/mT2 copper ≤ 0.0172Ωmm2/m
◆ Coating composition: 62%Sn36%Pb2%Ag (optional)
◆ Coating thickness: 0.01-0.05mm on one side, uniform coating, bright surface, smooth.
◆Coating Melting Point: 179°C
◆ Tensile strength: Soft state ≥25kgf/mm2 Semi-soft state ≥30kgf/mm2
◆Fused band elongation: soft state ≥35% 3/4 soft state ≥25% 1/2 soft state ≥15%
◆width error: ±0.1mm
◆ Thickness error: Interconnection zone ±0.01mm, Convergence zone ±0.015mm
Lead-containing silver coated tin copper strip
◆ Copper base: Imported refined toughness oxygen free copper/T2 copper, copper content ≥99.99%, conductivity ≥98%
◆ Copper base resistivity: Oxygen-free copper ≤ 0.0165 Ωmm2/mT2 copper ≤ 0.0172 Ωmm2/m
◆Coating composition: 63%Sn36%P2%Ag (optional)
◆ Coating thickness: 0.01-0.05mm on one side, uniform coating, bright surface, smooth.
◆Coating Melting Point: 179°C
◆ Tensile strength: Soft state ≥25kgf/mm2 Semi-soft state ≥30kgf/mm2
◆Fused band elongation: soft state ≥35% 3/4 soft state ≥25% 1/2 soft state ≥15%
◆width error: ±0.1mm
◆ Thickness error: Interconnection zone ±0.01mm, Convergence zone ±0.015mm
Lead tinned copper strip
◆ Copper base: Imported refined toughness oxygen free copper/T2 copper, copper content ≥99.99%, conductivity ≥98%
◆ Copper base resistivity: Oxygen-free copper ≤ 0.0165Ωmm2/mT2 copper ≤ 0.0172Ωmm2/m
◆Coating composition: 63%Sn37%Pb, 603%Sn40%Pb (optional)
◆ Coating thickness: 0.01-0.05mm on one side, uniform coating, bright surface, smooth.
◆Coating Melting Point: 183°C, 190°C
◆ Tensile strength: Soft state ≥25kgf/mm2 Semi-soft state ≥30kgf/mm2
◆Fused band elongation: soft state ≥35% 3/4 soft state ≥25% 1/2 soft state ≥15%
◆width error: ±0.1mm
◆ Thickness error: Interconnection zone ±0.01mm, Convergence zone ±0.015mm
Lead-free environmentally friendly tin coated copper tape
◆ Copper base: Imported refined toughness oxygen free copper/T2 copper, copper content ≥99.99%, conductivity ≥98%
◆ Copper base resistivity: Oxygen-free copper ≤ 0.0165Ωmm2/mT2 copper ≤ 0.0172Ωmm2/m
◆Coating composition: 96.5%Sn3.0Ag0.5%Cu, 96.5%Sn3.5Ag (optional)
◆ Coating thickness: 0.01-0.05mm on one side, uniform coating, bright surface, smooth.
◆Coating Melting Point: 217°C, 221°C
◆ Tensile strength: Soft state ≥25kgf/mm2 Semi-soft state ≥30kgf/mm2
◆Fused band elongation: soft state ≥35% 3/4 soft state ≥25% 1/2 soft state ≥15%
◆width error: ±0.1mm
◆ Thickness error: Interconnection zone ±0.01mm, Convergence zone ±0.015mm
