You’ve seen the numbers. With N-Type TOPCon technology capturing over 60% of the market in 2024 and cell efficiencies pushing past 26%, the decision to shift from PERC seems clear.
But as a decision-maker, you know the real challenge isn’t just hitting a peak efficiency number—it’s about consistently manufacturing reliable, high-yield, bankable modules at scale.
How do you ensure the theoretical advantages of TOPCon translate into predictable, long-term performance in the field? The answer lies not on the datasheet, but in the deep science of process control, where the gap between lab potential and industrial reality is closed.
The PVTestLab Optimization Framework: Turning Process Control into Bankable Performance
At PVTestLab, we help manufacturers move beyond theoretical models by providing an applied research environment to validate and optimize every process lever. We’ve developed a data-driven framework that directly connects material science and process parameters to the three outcomes that matter most: energy yield, long-term reliability, and bifacial gain.
This framework isn’t about chasing incremental gains in a lab; it’s about building the process stability that guarantees performance across millions of modules. It’s the science of making innovation repeatable, scalable, and profitable.
„Many can achieve high efficiency with TOPCon in a lab. The challenge is maintaining that performance with minimal degradation over 30 years under real-world conditions. That requires a fanatical focus on process stability—from firing temperatures to encapsulant selection. This is where we see the biggest variance between leading and lagging manufacturers.“ — Patrick Thoma, PV Process Specialist, PVTestLab
Mastering the Process Levers of TOPcon Performance
Our research has identified a few key areas that have an outsized impact on the industrial success of N-Type TOPCon technology. By systematically testing and validating these levers, you can de-risk your production and unlock the full potential of your modules.
Mitigating LeTID in N-Type Modules
A common misconception is that N-Type cells are entirely immune to degradation. While they solve the Boron-Oxygen LID common in P-type cells, they are still susceptible to Light and elevated Temperature Induced Degradation (LeTID). Our research connects this susceptibility to excess hydrogen introduced during deposition and passivation steps, which is then activated by specific thermal profiles during the firing stage.
PVTestLab’s Applied Testing: We run controlled experiments that simulate different industrial firing profiles and subsequent LeTID stress tests (e.g., 75°C at operating current). By precisely mapping thermal profiles against degradation rates, we identify the exact process window that minimizes LeTID activation without compromising cell efficiency.
Impact on Reliability and Yield: An uncontrolled process can lead to a 1-2% unexpected power loss from LeTID in the first 1,000 hours of field operation—a critical blow to a project’s financial model. A validated process, as shown in our tests, neutralizes this risk, ensuring the module’s performance remains stable and predictable, thereby protecting its bankability.
The Critical Role of EPE Encapsulants
With a bifaciality factor of around 85%, TOPCon modules generate a significant portion of their energy from the rear side. This makes the choice of encapsulant more critical than ever. While standard EVA is effective, advanced co-extruded encapsulants like EPE (EVA-POE-EVA) offer superior performance by combining the adhesion of EVA with the high durability and low water vapor transmission rate (WVTR) of POE.
PVTestLab’s Applied Testing: We conduct comparative lamination trials to analyze how different encapsulants interact with TOPCon’s sensitive passivated contacts and fine-line metallization. Our material testing services evaluate key factors like PID resistance, UV stability, and optical transmittance to quantify the real-world impact on bifacial gain and module longevity.
Impact on Bifacial Gain and Reliability: An optimized EPE encapsulant can improve rear-side energy gain by up to 3% compared to standard materials, thanks to better light transmission. More importantly, its superior moisture barrier drastically improves resistance to Potential Induced Degradation (PID), adding years of reliable performance to the module’s operational life.
Fine-Tuning Rear-Side Optics for Maximum Gain
The impressive bifaciality of TOPCon modules comes from their passivated rear surface. However, simply having a bifacial cell isn’t enough. The final energy gain is heavily influenced by the optical properties of the encapsulant and the backsheet, which work together to trap light that would otherwise escape.
PVTestLab’s Applied Testing: We create module prototypes using various combinations of transparent backsheets and encapsulants. Using our AAA Class flasher, we measure the exact bifacial gain under standard test conditions. This process allows us to isolate the optical contribution of each material and identify the combination that delivers the highest energy yield without increasing manufacturing complexity or cost.
Impact on Yield: With a bifaciality factor of around 85%, even small optical improvements have a big impact. Our trials show that a well-matched backsheet and encapsulant pairing can boost the effective energy yield by an additional 1-2% annually in typical albedo conditions—a significant gain that flows directly to the project’s bottom line.
Frequently Asked Questions about TOPCon Process Optimization
Isn’t TOPCon a mature enough technology to not require this level of testing?
While core TOPCon technology is well-established, the materials ecosystem around it—new encapsulants, pastes, and backsheets—is constantly evolving. What worked for PERC is not always optimal for TOPCon’s sensitive layers. Continuous process validation is a competitive advantage, not a remedial step.
How do tests at PVTestLab translate to our specific production lines?
Our entire facility is built with industrial-scale equipment from leading manufacturers like J.v.G. Technology. The process parameters we define—lamination recipes, curing times, thermal profiles—are designed to be directly transferable to a full-scale production environment. We bridge the gap between lab theory and factory floor reality.
Can’t we just rely on our material supplier’s datasheets?
Datasheets provide specifications under ideal lab conditions. They don’t account for interactions between different materials within a module laminate or the stresses of a specific lamination cycle. Our applied testing validates performance in a real, integrated system, revealing issues that datasheets can’t predict.
Your Path from Process Validation to Market Leadership
Adopting N-Type TOPCon is more than a technology upgrade; it’s an opportunity to deliver a new standard of performance and reliability. Realizing that potential requires moving beyond datasheet specifications and embracing the applied science of process optimization.
By validating material choices and fine-tuning process parameters in a real-world industrial environment, you can build modules that not only meet but exceed performance expectations. If you’re ready to de-risk your production and unlock the full bankable potential of your TOPCon modules, our team is here to help you build the process that gets you there.
Contact our process engineers today to build your validation and optimization plan.