China achieves the world’s most efficient silicon solar cell: a record marking a new milestone in photovoltaic technology

Chinese researchers have designed the most efficient silicon solar cell ever measured, achieving a certified efficiency of 27.81%.

The achievement, published in Nature in 2025, was independently verified by the German Solar Energy Research Institute of Hamelin, consolidating a breakthrough that redefines the limits of solar energy.

The protagonist is a HIBC (Hybrid Interdigitated Back-Contact) cell, which approaches the theoretical ceiling of silicon: the Shockley-Queisser limit, situated at 33.7%. Today, commercial cells hover around 26%, so each additional tenth represents a huge technical challenge.

The challenge of the fill factor

The Chinese team’s breakthrough focused on solving an old problem: the fill factor (FF), an indicator that measures a cell’s ability to harness the electricity it generates.

• A low FF implies current losses due to internal design or charge recombination.
• High-efficiency cells often stumble at this point, remaining more theoretical than practical.

The company Longi managed to overcome this obstacle with a hybrid solution based on two key innovations.

Two decisive advances

1. Laser-created back contacts

The team employed a laser process that crystallizes the contact material, generating ultra-conductive paths for electrons.

• Result: a more stable current.
• Exceptional fill factor: 87.55%, a value close to the ideal for single-junction silicon cells.

2. Advanced surface treatments and iPET

The second innovation was the iPET (in situ passivated edge technology) technique, which passivates the cell edges, areas especially vulnerable to losses.

• Charge recombination was significantly reduced.
• Electrical leaks that limited performance were “silenced”.

Certification and next steps

The European certification confirmed the efficiency of 27.81% under strictly controlled conditions.

Longi researchers are already working on two fronts:

• Optimizing electrical contacts to further reduce internal resistance.
• Refining the laser process so that the technology can exit the laboratory without becoming more expensive.

The goal is not just to break records, but to achieve a scalable and affordable technology, capable of being produced by millions and at reasonable prices.

Impact on the solar industry

China has demonstrated an enormous capacity to scale photovoltaic innovations, from PERC to TOPCon. The question now is whether HIBC technology can follow the same path.

Several European and Asian companies have already begun to adapt pilot lines to assess the real production costs.

Cumulative benefits of efficiency

Although the improvements seem incremental, their impact is enormous:

• They allow more homes and businesses to be supplied without installing additional structures.
• They facilitate energy communities in areas with limited space.
• They reduce costs and accelerate the electrification of industries still dependent on gas.
• They prepare the ground for tandems with perovskites, where HIBC cells could act as the lower layer and exceed 30% total efficiency.

The efficiency record achieved by Longi’s HIBC solar cell is not just a technical triumph: it is a step towards cleaner, more accessible solar energy that is compatible with the planet’s limits.

Each advance brings the possibility of a future where renewable electricity is more abundant, economical, and capable of sustaining the global energy transition closer.