Selecting next-generation cells like TOPCon is the right call—the first step toward industry-leading module efficiency. But a critical question remains that will determine profitability: how do you manufacture these advanced, often fragile, cells at scale without compromising reliability or yield?
The gap between a promising datasheet and a bankable, high-volume product is wider than ever. The interconnection technologies that unlock higher power—Multi-Busbar (MBB), Zero-Busbar (ZBB), and shingled designs—introduce new materials, new stressors, and new potential failure modes. Relying on outdated validation methods is a direct threat to your return on investment.
Here, design innovation meets manufacturing reality. This guide provides a framework for qualifying these next-generation technologies, helping you turn production uncertainty into a competitive advantage.
Why Standard Reliability Testing Is No Longer Enough
For years, IEC 61215 has been the benchmark for module reliability. But its test sequences were designed for thicker, more robust p-type PERC cells with traditional busbars. For today’s advanced modules, it’s the bare minimum—not a guarantee of long-term performance.
Emerging research and field data show that these new designs have unique vulnerabilities:
Thermo-Mechanical Stress
ZBB and shingled modules use laminates and adhesives instead of soldered ribbons, creating different stress points during thermal cycling. Standard tests may not trigger these failure modes.
Material Degradation
The electrically conductive adhesives (ECAs) in shingled modules can degrade differently than solder under prolonged damp heat and humidity-freeze cycles.
Microcrack Sensitivity
Thinner n-type cells are more susceptible to microcracks during the high-precision stringing and lamination processes that MBB and ZBB designs demand.
To de-risk these technologies for mass production, you need a „Qualification Plus“ approach—one that goes beyond the standards to simulate real-world stress over a 25-year lifetime.
A Framework for Qualifying Advanced Interconnections
At PVTestLab, we validate new module designs on a full-scale industrial production line, providing the data you need to scale with confidence. Here’s how we qualify the leading interconnection technologies.
Multi-Busbar (MBB) Modules
MBB technology is the current workhorse for n-type TOPCon, increasing current collection and reducing resistive losses. But its reliance on more, thinner wires creates new process control challenges.
Joining Method: Soldered multi-wire ribbons (typically 12BB to 16BB) are applied to the cell surface using specialized tabber-stringers.
Reliability and Stress Testing: The primary risk with MBB is process-induced microcracks. Often invisible after production, they can propagate into yield-killing failures in the field. We use extended thermal cycling (TC600—three times the IEC standard) and post-stress high-resolution electroluminescence (EL) imaging to detect these hidden defects and assess the durability of the solder bonds.
Process Optimization: This stress test data creates a direct feedback loop. By correlating specific microcrack patterns with machine parameters, we help you fine-tune screen printing pressure, soldering temperatures, and stringer alignment. This data-driven approach is key to refining your Prototyping and Module Development cycle.
Manufacturing Insight: We’ve found that a 5% adjustment in the thermal profile of a tabber-stringer can reduce post-lamination microcrack incidence by over 50%, a crucial improvement for maximizing the yield of high-efficiency cells.
Zero-Busbar (ZBB) Modules
ZBB technology offers a leap in both efficiency and aesthetics by eliminating busbars entirely. It relies on a laminated copper wire composite film to make contact with the cell, a process that demands exceptional precision.
Joining Method: A specially designed encapsulant film embedded with thin copper wires is placed over the cells. During lamination, heat and pressure form the electrical connections.
Reliability and Stress Testing: The critical point of failure is the laminate itself. We perform extended damp heat tests (DH2000) and system-voltage bias testing to check for delamination, moisture ingress, and potential-induced degradation (PID) at the cell-wire interface. Mechanical load sequences are also essential to ensure the bond withstands real-world flex and stress.
Process Optimization: Successful ZBB production hinges on the lamination process. Our trials focus on defining the optimal recipe of temperature, pressure, and curing time for your specific combination of cells and laminates. This prevents common yield killers like contact resistance and delamination, ensuring consistent, high-quality output.
Patrick Thoma, PV Process Specialist: „True innovation isn’t just about the cell; it’s about the industrial process that brings it to life. Our role is to bridge that gap, using real production data to make sure a brilliant design becomes a reliable, scalable product.“
Shingled Modules
Shingled modules maximize the active area by overlapping cells, eliminating the need for ribbon interconnects and boosting cell-to-module (CtM) efficiency. This innovative design relies entirely on the performance of adhesives.
Joining Method: Cells are cut into „shingles“ and bonded together using an Electrically Conductive Adhesive (ECA). This creates a continuous, high-density string of cells.
Reliability and Stress Testing: The long-term stability of the ECA is critical. We use aggressive humidity-freeze and dynamic mechanical load tests designed specifically to stress the adhesive bonds. This is crucial for evaluating new ECA suppliers or qualifying process changes. Our Material Testing and Lamination Trials are designed to isolate and validate each component of the module stack.
Process Optimization: The primary challenges in shingled manufacturing are precision cell cutting and consistent adhesive application and curing. Our validation trials identify optimal laser cutting parameters to minimize edge defects and define the precise thermal profile needed to fully cure the ECA without thermally stressing the cells.
Manufacturing Insight: In a recent trial, we discovered that an improper ECA curing profile led to a 3% power loss after just 400 thermal cycles. By optimizing the curing time and temperature on our line, we eliminated the degradation, directly protecting the module’s bankability.
Frequently Asked Questions
How long does a typical validation project take at PVTestLab?
A focused lamination trial or material test can be completed in as little as a single day. A full module validation project, including prototyping and stress testing, typically ranges from one to three weeks, depending on the complexity and test sequences required.
Is our intellectual property safe during testing?
Absolutely. We operate under strict Non-Disclosure Agreements (NDAs) and ensure complete client confidentiality. Your proprietary materials, cell designs, and process data are handled with the utmost security. Our business is providing objective data, not developing our own products.
Can we test our own proprietary materials, like a new encapsulant or backsheet?
Yes. Our facility is designed for this purpose. We provide a controlled, industrial environment where you can see exactly how your innovative materials perform under real manufacturing conditions and in combination with other components.
What’s the difference between testing at PVTestLab versus an academic lab?
The key difference is our focus on industrial reality. Academic labs are excellent for fundamental research, but our facility is a complete, full-scale production line operated by German process engineers from J.v.G. Technology. We don’t just test if a concept works; we provide the data to prove it can be manufactured reliably and efficiently at scale. You can learn more about our unique approach here.
Your Partner for Scalable Success
Choosing the right interconnection technology is just the beginning. What truly drives market success is ensuring it can be built reliably, at high yield, and with long-term bankability. The path from an innovative concept to a mass-produced reality requires more than just a datasheet—it requires robust, data-driven validation in a real-world manufacturing environment.
Stop guessing and start validating. De-risk your next-generation module design and accelerate your time to market.
Ready to discuss your project? Schedule a technical consultation with our process engineers today.