Ecoprogetti joins the European Solar Manufacturing Council (ESMC)November 29, 2023
Automation of Photovoltaic Panel Soldering (Bussing): How Does It Work?February 12, 2024
Manufacturing Process of Photovoltaic Panels
Until a few years ago, and even today in many parts of the world, the production process of photovoltaic panels was exclusively or mostly reliant on skilled labor. These workers, depending on their roles, carried out various panel assembly and quality control operations using simple manual tools. Such an approach, as evident, significantly risks compromising the quality of the photovoltaic panel. While human creativity and craftsmanship are fundamental in the production of items like bags, shoes, and clothing, in the case of photovoltaic panels, what matters most is the level of precision achieved throughout the entire manufacturing process, including the creation of packaging suitable for shipping. The strength of the most advanced companies in the photovoltaic panel production sector lies precisely in their ability to guarantee this level of precision at 100%. How can we transition from a manual manufacturing process to an automated process that includes the packaging of photovoltaic panels?
The answer can only come from technology. Today, the industry has cutting-edge machinery capable of working in synergy to create next-generation photovoltaic modules, from P-type PERC, N-type TOPCon, N-type HJT cells to semi-flexible panels, and BIPV panels. While these machines can be used independently, they offer greater advantages when integrated into a complete or partial production line. Production lines, also known as photovoltaic lines, consist of a sequence of machinery designed (and programmed) to handle specific operations.
Among the main ones, we can mention:
- Stringer → This machine's task is to interconnect photovoltaic cells into strings using ribbon (copper conductor with surface treatment). The strings are deposited one by one on the support glass based on their respective polarities. This process takes place within a few seconds with insignificant breakage rates. There are various soldering systems, and Ecoprogetti has patented the hybrid string soldering method to optimize soldering quality and minimize cell breakage.
- Automatic Bussing Machine → It performs the soldering of interconnections in a photovoltaic panel, joining the various cell strings already positioned on the glass, both at the top (head) and bottom of the panel. The bussing process is crucial, and the soldering must be of excellent quality, as it can create hot spots on the panel due to various factors, such as cold soldering, heterogeneous contact types (different pressure or time in soldering), or unsoldered ribbons. All of these possibilities can occur during manual soldering by an operator. Furthermore, the automatic machine optimizes the economic aspect of the process related to speed: an operator takes about 3-4 minutes to complete the soldering of a panel's interconnections, while the machine requires less than 30 seconds and avoids unnecessary material waste.
- Laminator → The laminator's function is to fuse together the materials that make up the sandwich of the photovoltaic panel. The correct procedure is a thermal process divided into multiple phases, subjected to periods of vacuum, while always maintaining temperature control. It involves the polymerization of EVA or other encapsulants (e.g., POE, Ultrafast cure EVA, etc.). In a complete line, the contribution of additional units, such as the "Cooling Press," which is the laminator section responsible for cooling the panel and maintaining its shape after lamination, should not be excluded.
- Trimmer → It is responsible for trimming the excess material after lamination. Trimming can be done manually on a multifunction table with a 360° rotating piston and a special knife, or it can be performed automatically by a dedicated machine for this purpose. This machine is capable of trimming all four sides of the panel simultaneously and disposing of the waste in designated compartments in no time.
- Framing Machine → The framing phase can also be managed by a dedicated machine, in this case called a framing machine. This machine is essential for perfecting the manufacturing of photovoltaic panels. The framing machine applies aluminum frames around the laminated module, providing greater strength to the finished product and facilitating installation for the installer.
- Junction Box Applicator → Equipped with junction box storage units, a silicone dispenser with XY axis, glue dispenser, 4-axis robot, automatic conveyor belt, induction soldering unit, and units for positioning junction box covers, the junction box applicator is the necessary automated system for the placement, soldering, and dispensing of silicone/glue on the junction box.
- Module Testing → The quality control phase can also be managed along the photovoltaic line. The machinery that typically completes the production cycle of a good photovoltaic line includes electroluminescence (checks for micro-cracks, cell breaks, dark spots, unsoldered cells, bus bar interruption), photovoltaic simulator (measures I-V curve), and hi-pot (electrical insulation). These are a sequence of tests necessary to confirm the quality of the manufacturing process and the reliability of the photovoltaic module's performance once completed, ensuring the quality of the product delivered to the customer.
Benefits of automated manufacturing
An automated manufacturing process differs from its manual counterpart in several ways. Firstly, in terms of speed, the modules are assembled in less than 30 seconds, resulting in significant time and cost savings. The full compatibility of the lines with different cells and components also allows complete adaptation to new market developments, with a very low risk of obsolescence. Finally, there is the great advantage of the quality of the modules that come out of an automated line: thanks to the precision of the soldering, the care in assembly, the absence of performance drops (as with a worker after hours of work), but above all, due to the final tests conducted by the final testing section, the company is guaranteed a product that meets expectations, ready to be packaged on its pallet, sold, and installed. If you are looking for more information on photovoltaic lines and related machinery, please feel free to contact us via email or phone. Our experts are at your disposal!