Silicon is supposed to be running out of road, yet Longi's latest gain of 0.16 percentage points is larger than the previously announced increment, which measured at 0.09. The Chinese manufacturer presented its record cell at the ENERGY EXPO in Romania in September, after earlier results of 28.04 and 28.13 percent this year. Longi says the cell has reached 96.2 percent of crystalline silicon's theoretical limit, which on that figure puts the ceiling at around 29.4 percent, leaving little more than one percentage point left to claim. The hybrid interdigitated back contact (HIBC) design was set out in a scientific paper the company published last November.
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Mixing cell technologies
Longi describes HIBC as combining the strengths of several mainstream cell technologies, with changes to cell structure, materials, manufacturing processes and efficiency modelling. Back-contact designs put both electrical contacts on the rear of the cell, leaving the sun-facing side free of metal shading. Modules rated above 700 W were also shown at the same event, which Longi says marks the successful mass production of the technology.
Silicon's ceiling and the next steps
With silicon this close to its theoretical limit, attention is now shifting to tandem cells, namely the stacking of perovskite on silicon. Longi itself developed a silicon-perovskite tandem with 35.5 percent efficiency earlier this year, an improvement of almost two percentage points in three years. Two German labs sit behind several of the numbers: ISFH in Hamelin verified the 28.29 percent, while Fraunhofer ISE's CalLab measured Longi's 26.2 percent silicon module record in 2025 and confirmed the 47.6 percent quadruple-junction cell that remains the world's most efficient. (TF)
