A solar module is designed to perform for 25 years or more, yet its long-term reliability is often decided in a fraction of a second during production. A hidden flaw introduced this early can compromise the performance and profitability of an entire solar project years down the line.
That critical moment is cell soldering, where individual solar cells are connected into strings. The choice of technology here—between traditional infrared heating and modern induction soldering—has a significant impact on the quality of the final product.
Understanding this difference is essential for any entrepreneur or investor planning to build a successful solar manufacturing business.
The Foundation of a Module: The Tabber Stringer
The machine at the heart of this process is the tabber stringer. Inside a solar module factory, it performs one of the most delicate and vital tasks: soldering thin metal ribbons, or ‘tabs,’ onto solar cells to connect them electrically. These connected cells form a ‘string,’ and multiple strings are assembled to create a complete solar module.
Soldering, of course, requires heat. How that heat is applied marks the fundamental difference between infrared and induction technologies—and the key to preventing the invisible damage that can lead to module failure.
Two Methods, Two Different Impacts on Your Cells
At its core, the debate between induction and infrared is a question of precision. One method heats everything in its path, while the other targets only the component that needs to be heated.
Infrared (IR) Soldering: The Traditional Approach
Infrared soldering uses high-intensity lamps to heat the solar cell and the copper ribbon simultaneously. The light energy is absorbed by both surfaces, raising their temperature until the solder melts and creates a connection.
While this method has been used for many years and typically involves a lower initial equipment cost, it has a significant drawback: it subjects the entire solar cell to intense thermal stress.
Induction Soldering: The Modern Standard
Induction soldering operates on a more precise principle. It uses a high-frequency magnetic field to generate heat directly within the copper ribbon itself. The solar cell, being non-metallic, is not affected by the magnetic field and remains significantly cooler.
The heat is created exactly where it is needed—in the ribbon—and is then transferred to the solder to form a strong, reliable connection. This process is incredibly fast, efficient, and gentle on the cell.
This distinction is more critical today than ever before. The solar industry is rapidly advancing, with new cell technologies like TOPCon and HJT becoming the standard. These cells are not only more efficient but also significantly thinner and more fragile than their predecessors, making them far more susceptible to damage from thermal stress.
The Hidden Cost of Thermal Stress: Micro-Cracks
The primary risk of the high, untargeted heat from infrared soldering is the creation of micro-cracks. These are tiny, often invisible fractures in the solar cell that can occur when it experiences rapid and uneven temperature changes.
While a module with micro-cracks might pass initial quality control tests, the damage becomes apparent over time. Under real-world conditions of heat, cold, and mechanical load, these tiny cracks can grow, leading to severe consequences:
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Power Loss: The cracks interrupt the flow of electricity, reducing the module’s power output.
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Hotspots: Damaged areas can overheat, further degrading the cell and surrounding materials, and in extreme cases, posing a fire risk.
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Complete Failure: Over years of operation, micro-cracks can lead to the complete failure of the module, resulting in warranty claims and damage to your company’s reputation.
For investors and operators of solar power plants, module quality is directly linked to a project’s financial viability, or ‘bankability.’ Modules prone to micro-cracks pose an unacceptable long-term risk.
A Technical Comparison: Why Precision Matters
When evaluating the two technologies for your factory, the choice impacts everything from cell integrity to your operational budget.
Cell Stress and Reliability
Induction soldering minimizes thermal stress on the cell. By heating only the ribbon, it protects the delicate silicon structure, virtually eliminating the risk of inducing micro-cracks. This is the single most important factor for ensuring the long-term module reliability your customers demand. Infrared technology, by its nature, exposes the entire cell to high heat, creating a significant risk of damage, especially with modern, thin-wafer cells.
Process Speed and Precision
Induction is a much faster and more controllable process. The heat is generated instantly and precisely, allowing for shorter cycle times and higher throughput in the production line. This efficiency contributes directly to a factory’s overall output and profitability.
Operational Costs
While infrared systems may have a lower initial purchase price, induction technology offers a lower total cost of ownership. Induction heaters are remarkably energy-efficient, consuming significantly less power than IR lamps.
They also have no consumables. IR systems, on the other hand, require the regular replacement of expensive lamps, adding to recurring costs and maintenance downtime.
Our Perspective: Building for Long-Term Success
At J.v.G. technology, we have built solar production lines across the globe for over 25 years. Our focus has always been on providing our partners with robust, reliable, and profitable manufacturing solutions.
That is why every tabber stringer machine we design and build uses induction soldering technology exclusively.
We believe that protecting the integrity of the solar cell is non-negotiable. The long-term performance of your modules and the reputation of your brand depend on it. Choosing induction is not simply a technical preference; it is a commitment to quality that secures the value of your investment for decades. This philosophy of building for reliability is at the core of all our turnkey production lines.
Frequently Asked Questions
Is infrared soldering now an obsolete technology?
It isn’t obsolete, but it is a legacy technology that presents increasing risks when used with modern, high-efficiency, thin-wafer cells. For new factories aiming to produce top-tier modules, induction is widely considered the superior standard.
Is induction technology significantly more expensive?
The initial investment for an induction-based stringer is higher. However, when you factor in lower energy consumption, no replacement lamps, and reduced product rejection rates, the total cost of ownership is often lower than with infrared systems.
Does this soldering choice truly affect my business’s profitability?
Absolutely. It directly impacts your product quality, which influences your brand reputation, warranty claims, and ability to secure large-scale projects. Producing higher-quality, more reliable modules leads to greater customer trust and long-term profitability.
The First Step to a Successful Factory
Understanding these fundamental technical decisions is essential to building a world-class solar manufacturing business. The choice you make for your soldering technology will echo in the performance of your products for the next 25 years.
You bring the vision and the ambition. We are here to provide the engineering expertise and hands-on support to ensure your project is a success from day one.
If you are considering establishing your own production facility, we invite you to speak with us. Contact our experts to start the conversation.