SHJ Solar Modules Break Efficiency Records with 25.44% Certified Performance

Record-Breaking Solar Performance

Solar technology has taken another significant leap forward with reports of silicon heterojunction (SHJ) modules achieving certified 25.44% efficiency at Fraunhofer ISE. According to the analysis published in Nature Communications, this performance surpasses the previous large-area module record of 24.9% set by Maxeon earlier this year and edges past LONGi’s 25.4% benchmark from July 2024.

The champion modules, covering a masked area of 1.63 m², reportedly achieved an impressive fill factor of 86.03% – a critical metric that indicates how effectively solar cells convert sunlight into electricity. Industry observers note this represents substantial progress in commercial-scale solar manufacturing rather than just laboratory demonstrations.

Surface Engineering Breakthrough

What makes this development particularly noteworthy, according to technical sources, is the innovative approach to surface passivation. The research team apparently tackled a longstanding challenge in crystalline silicon solar technology: the inherent conflict between light-harvesting efficiency and surface quality.

Traditional pyramid-like surface structures with (111) orientation have been ideal for capturing light but problematic for surface passivation because peaks and valleys tend to host dangling bonds that reduce efficiency. The new approach reportedly adapts rear-side polishing techniques originally developed for PERC solar cells, creating surfaces with mixed facet orientations that significantly improve performance.

Technical documents indicate the team used silicon nitride as a protective mask during adjusted saw damage etching, transforming the surface crystallography from dominated (111) conditions to combinations of (311) and (411) facets. This surface engineering, combined with optimized wet chemistry processes, apparently enabled the exceptional passivation quality.

Nano-crystalline Silicon Innovations

The research reportedly achieved another critical advancement through nano-crystalline silicon (ncSi) contact layers. Analysis suggests that on textured surfaces, ncSi formation remained limited with smaller, isolated distributions. However, on the newly engineered shallow slope facets and planar areas, the ncSi formation dramatically improved, extending across entire layers as columnar structures.

Perhaps most impressively, sources indicate the team managed what they describe as a “progressive transition” from RF PECVD processes to VHF bulk layer deposition. This approach apparently leveraged the strengths of different plasma technologies – RF for nucleation and VHF for fast nano-crystallization – while using a resistive incubation layer to screen out excessive bombardment.

The oxygen doping strategy for the window layer also represented a careful balancing act. Technical reports suggest that while higher oxygen ratios improved transparency, they reduced crystallinity. The optimal 80% oxygen ratio apparently delivered the necessary tradeoff between optical engineering and electrical performance.

Cell-to-Module Efficiency Preservation

What really sets this achievement apart, according to industry analysts, is the remarkable 98.6% cell-to-module (CTM) ratio. This metric measures how much of the individual cell efficiency translates to the final module performance – an area where many high-efficiency technologies traditionally struggle.

The analysis reveals that front-back contact (FBC) SHJ technology demonstrated significantly better CTM performance compared to back-contact (BC) alternatives. While FBC technology achieved 94.2% defined CTM, BC technology reportedly managed only 92.7%, with most losses occurring in fill factor performance.

Technical sources attribute the superior CTM performance to several factors: minimal optical shading from smart-wire technology using 28 round ribbons, narrow overlaps between neighboring cells, and reduced ohmic losses. The front-side ribbon ohmic loss was reportedly only 0.6% in the FBC case.

Industry Implications and Validation

The independent certification at Fraunhofer ISE provides crucial validation for the technology’s commercial potential. Three modules sent for testing all reportedly achieved approximately 25.4% efficiency, with the champion reaching 25.44%. Meanwhile, cells from the same technology measured at ISFH apparently reached 27.4% efficiency.

This development comes at a time when the solar industry is aggressively pursuing efficiency improvements toward the theoretical 29.4% limit for silicon solar cells. The reported minority carrier lifetime of 12 milliseconds from low to median injection and over 5 milliseconds at high injection represents what sources describe as unprecedented performance across the injection range for silicon solar cells.

Industry observers suggest that the combination of high cell efficiency and exceptional CTM ratios could significantly impact commercial solar deployment. The technology apparently demonstrates that laboratory breakthroughs can translate to manufacturable modules without the substantial efficiency losses that often plague scale-up efforts.

Technical Validation and Future Outlook

The research team reportedly employed multiple validation methods, including high-resolution transmission electron microscopy and Raman spectroscopy, to characterize the material properties and confirm the mechanisms behind the performance improvements. The consistent results across different measurement techniques and independent certifications apparently provide strong evidence for the technology’s robustness.

As the solar industry continues its relentless push toward higher efficiencies, this SHJ technology represents another step in the evolution from Sanyo’s original HIT cell development through PERC and TOPCon technologies to today’s advanced heterojunction approaches. The reported achievements suggest there remains significant headroom for improvement within silicon-based photovoltaics before reaching fundamental physical limits.

With module efficiencies now consistently breaking the 25% barrier and cell efficiencies approaching 28%, industry analysts suggest we’re witnessing the maturation of silicon solar technology into its most efficient form yet. The coming years will likely see whether these laboratory achievements can scale to mass production while maintaining their exceptional performance characteristics.