Researchers Reduce Performance Losses in TOPCon & SHJ Solar Cells

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Researchers at Hebei University, China have developed an organic solution that can compensate for performance losses caused during the cutting and separation process while assembling the shingle solar panels.

The team’s study provides a new passivation technology that can recombine the loss on the edge surface and can easily be integrated into the current production line.

They found that the technique could increase the fill factor of a 24.4%-efficient HJT device from 77.9% to 82.5%, with the efficiency itself growing by 1% to 2%.

Efficiency losses are caused by the integration of stripes into the shingles panels during the cell-to-module (CTM) process, as the solar cells are cut into sub-cells through laser slicing technology.

“In order to compensate this recombination loss during the CTM process, we used an organic polymer ink mixed by ethanol, water and Nafion to form the passivation layer…We show that the organic passivation coating can substantially reduce the newly formed edge loss from laser scribing,” the researchers said.

The team said the spraying method can produce a uniform film on the passivate side compared to the unpassivated one.

The solar cells with the passivation layer were found to be brighter than those without one. This indicated that the organic passivation layer had a satisfactory edge passivation effect for both the tunnel oxide passivated contact (TOPCon) and silicon heterojunction (SHJ) solar cells and the edge recombination losses were largely reduced.

Researchers said the device can achieve long-term stability through the careful controlling of humidity and simple packaging technology.

The large performance losses that the TOPCon and SHJ cells have in the cell-to-module process, is one of the main obstacles in the upgradation of the photovoltaic industry.

The researchers hope their development can be utilized to help address the issue and bring about necessary upgrades in the PV industry.

In November 2022, China-based solar cell and module manufacturer Jinko Solar announced achieving a record maximum solar conversion efficiency of 26.1% in its 182 mm N-type module, which is Jinko’s latest TOPCon cell technology.

Researchers from China, Australia, and Singapore recently in October 2022 used a tube-type industrial plasma-assisted atomic layer deposition method and announced a maximum power conversion efficiency of 22.8% in a 613-Watt TOPCon module with 60 cells.