Christopher Hailstone is a leading voice in energy management and grid security, renowned for his ability to translate complex photovoltaic physics into practical utility solutions. With a career spanning the evolution of renewable infrastructure, he has become a go-to expert for understanding how microscopic changes in cell architecture impact macroscopic grid reliability. As the solar industry moves toward higher efficiency benchmarks in 2026, Hailstone’s insights into the collaboration between academic pioneers and global manufacturers provide a roadmap for the next generation of energy delivery.
The following discussion delves into the technical intricacies of back-contact TOPCon (TBC) solar cells, specifically focusing on the mitigation of cut-induced losses during manufacturing. We explore the strategic shift toward gap-region cutting to halve efficiency degradation and the critical role of 0.3 mm gap widths in maintaining performance under low-light conditions. Furthermore, the conversation highlights the economic benefits of zero-busbar designs and the significant achievement of reaching 27% power conversion efficiency in large-scale production.
The industry has moved decisively toward dividing full-size solar cells into half, third, or even quarter segments; could you explain why this structural change is so vital for managing resistive losses?
In the current landscape of 2026, we are obsessed with squeezing every possible milliwatt out of a module, and cutting cells is a fundamental part of that strategy. The primary reason we do this is that resistive losses scale quadratically with the length of the cell, so by shortening the path electricity has to travel, we significantly boost the overall output. It has become a standard practice in crystalline-silicon manufacturing because it allows us to handle higher currents without the heat and efficiency penalties that plagued older, full-cell designs. However, it isn’t a free lunch; the moment a laser touches the silicon, it creates raw, unpassivated edges that can act like a “black hole” for energy if not managed correctly. We are essentially balancing the massive benefits of reduced resistance against the new challenge of surface defects and dangling bonds at the cut site.
When a laser scribes these cells, it exposes unpassivated edges that can lead to carrier recombination; how does the “gap-region” cutting strategy fundamentally change the physics of these losses?
The beauty of the research coming out of the partnership between UNSW and DAS Solar is that it identifies a “sweet spot” for the laser to strike. When you cut through the emitter region, you are exposing the very heart of the cell’s charge-collection zone, which leads to a dramatic drop in performance as photogenerated electrons and holes recombine at that broken edge. By shifting that cut to the gap between the n-type and p-type contacts, we spatially separate the damaged edge from the heavily doped junctions. Our simulations show that this simple shift in placement can reduce efficiency penalties by approximately 50% compared to traditional methods. It’s a sophisticated way to minimize edge-induced carrier recombination without needing the extra, costly step of adding secondary edge passivation during the manufacturing process.
The research mentions a very specific 0.3 mm gap width as a design guideline; why is this particular measurement so critical for maintaining efficiency across different lighting conditions?
Precision at the sub-millimeter level is what separates world-class modules from mediocre ones, and that 0.3 mm gap is a perfect example of optimized engineering. This width is specifically designed to minimize the total efficiency loss by balancing the physical space needed to prevent recombination with the need to keep the cell compact. We found that under low irradiance, these cut cells actually become more sensitive to losses because photogenerated carriers are more likely to wander laterally toward those active cut edges before they can be collected. Having that optimized 0.3 mm gap acts as a buffer, ensuring that even when the sun is low or the sky is overcast, the resistive losses and hole transport remain stable. It’s about ensuring the cell remains robust and reliable in real-world environments, not just under perfect laboratory flash-testers.
With the successful fabrication of a TBC cell reaching 27% efficiency, what does the implementation of a zero-busbar design mean for the future of sustainable manufacturing?
Reaching a 27% power conversion efficiency is a monumental milestone that proves back-contact TOPCon technology is the new gold standard for the industry. The move to a zero-busbar, or ZBB, design is particularly exciting because it tackles one of the biggest cost bottlenecks in solar: the use of silver. By utilizing a ZBB layout, we significantly reduce the silver content required for metallization, which makes the cells both cheaper to produce and more environmentally sustainable. This design doesn’t just look cleaner; it fundamentally improves the electrical behavior of the device by reducing shading and optimizing current collection. When you combine high-GW-scale production with these material savings, you get a technology that is ready to dominate the utility market.
What is your forecast for the adoption of back-contact TOPCon technology?
I expect back-contact TOPCon technology to become the dominant architecture for all new utility-scale projects within the next few years. The combination of 27% efficiency and the ability to mitigate cutting losses through gap-region optimization makes it an unbeatable proposition for developers. We are seeing a massive shift where the industry is moving away from simpler PERC designs toward these more complex, yet higher-yielding back-contact structures. As manufacturers like DAS Solar continue to refine these laser-cutting techniques to preserve every bit of energy, the cost-per-watt will drop so significantly that older technologies will simply be unable to compete. The grid of the late 2020s will be powered by these high-efficiency, low-silver-content modules, providing a level of reliability and performance that was unthinkable just a few years ago.
