Automation of PV Panel interconnection soldering (Bussing)
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Automation of Photovoltaic Panel Soldering (Bussing): How Does It Work?

It's important to remember that bussing or interconnecting photovoltaic cells through soldering of the interconnections between cell strings occurs after the cell tabbing process (performed by the Tabber-Stringer machine). The photovoltaic cells connected in series by the stringer form strings of cells positioned on the glass, which can be made up of 2 to 12 cells (usually), and these are then "interconnected" (bussed) together using a 5mm wide ribbon (usually) to create the collector grid. The need to reduce production costs is driving a constant reduction in the thickness of wafers and cells. As a result, the soldering process has become more challenging because thinner cells are more sensitive to micro-cracks caused by temperature.
In recent years, the number of busbars in photovoltaic cells has increased, leading to a corresponding increase in the number of soldering of interconnection’s processes, also known as "bussing." Cells must be connected through soldering, and to do this quickly and efficiently, specialized machinery is required. In less advanced industries, this operation is still entrusted to skilled labor. Workers use a hand soldering iron to individually solder the ribbons of the strings and create the required interconnections. It is clear that to support high volumes of photovoltaic panel production and maintain equally high quality, dedicated machinery for interconnection soldering must be used in your PV line. How do these machines work? And what type of soldering do they perform? The machine for soldering the panel busbars is called automatic bussing because it boasts independent operating systems, without the need for external operators. These machines can handle various automatic operations related to soldering, including:
  • Automatic loading and unloading of panels
  • Cutting, bending, and positioning of the ribbon (including overlapping ribbon, L-bend, U-ribbon ribbon and so on…)
  • Induction soldering of connection headers
  • Soldering of centralized panels
  • Soldering time <30 seconds

Configuration of automatic bussing

Our automatic bussing is configured to work with both old and new-generation photovoltaic panels with 60 to 72 cells. Through specific modifications, it is also possible to use bussing on half-cell centralized panels or panels with more than 72 cells. The total production capacity is 300 MW/year, with a cycle time of less than 30 seconds (down to 25 seconds/module for certain panel types). The machine is compatible with various sizes of photovoltaic cells, ranging from wafer sizes M6 up to G12. Once the settings are configured, the machine operates automatically with very little need of maintenance, without the need for external controls or monitoring activities. The Ethernet connection installed in the machine is available for immediate remote assistance.

Advantages of Automatic Interconnection Soldering / Automatic Bussing

Interconnection soldering performed with the Automatic Bussing machine offers significant advantages, making this methodology one of the best available. Among the key strengths, we can highlight:
  • Induction heating focuses on specific areas without heating neighboring zones.
  • Induction heating does not burn fossil fuels, making this soldering method safer for both you and the environment.
  • The heating pattern is replicable indefinitely.
  • There is no energy waste.
  • Reduced maintenance and cleaning requirements.
  • Production optimization due to the rapid attainment of the ideal soldering temperature.
  • Cell breakage rate lower than 0.1%.

Simplifying the High-Quality Bussing Process

The interconnection soldering machine is an integral part of photovoltaic module production lines and performs at its best in large installations. On-site installation is carried out by our specialized personnel, with full assistance for machine startup and configuration. The user interface, in the form of a simple touchscreen display, allows operators to configure production settings based on specific requirements. Ease of use is another factor that enables the machine to be operated by non-specialized personnel.

Problems Arising from Manual Bussing (Attention!)

Low-cost panels manufactured with manual bussing can suffer from various problems right from the start, which can, in the worst cases, compromise the usability of the photovoltaic panel itself. The bussing process has become even more crucial in recent years due to the constant trend of thinner wafers and cells, driven by the need to reduce production costs. Thinner wafers and cells result in increased fragility and sensitivity to micro-cracks. The soldering process has never been as demanding as it is today, with the need for state-of-the-art automatic bussing machines. Opting for manual bussing can lead to various issues, such as:
  • Weak or non-resistant cold soldering
  • Inconsistent contacting (due to different pressures or soldering times)
  • Unsoldered or partially unsoldered ribbons
These scenarios, both in the short and long term, can lead to the notorious hotspots on the photovoltaic panel, reducing or entirely negating the module's efficiency. All of this has significant economic implications: thanks to the high speed of automatic bussing machines (<30 seconds per panel compared to the 3-4 minutes of an operator), industrial production is multiplied, with the certainty of a quality standard otherwise impossible to achieve. Now that you know everything about interconnection soldering, it's time to take action. Our experts are at your disposal to provide personalized and immediate consultation in designing your photovoltaic module production plant. Contact us without obligation via email or phone and discover how we can assist you!

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