Imec and Jolywood R&D collaboration on bifacial n-PERT solar cells hits a record 23.2% efficiency

An ongoing R&D collaboration between Imec and Jolywood (Taizhou) Solar Technology Co, the PV module manufacturing arm of major PV backsheet manufacturer Jolywood (Suzhou) Sunwatt Co, have reported an n-PERT (Passivated Emitter and Rear Totally diffused) bifacial solar cell with a conversion efficiency of 23.2%, a new record. 

Imec announced the results at SiliconPV 2019, which were measured by ISFH Caltec, with a clear path to achieve conversion efficiencies above 24%.

Jia Chen, R&D director at Jolywood: “Jolywood targets to bring the best solar solution to the market. Devoted to R&D and manufacturing of the world’s best n-type cells and modules, we believe n-type technology can contribute to the industry with high performance, high reliability and low LCOE. We have chosen imec to help us reach that target because of their unique expertise and research infrastructure. We are also developing bifacial n-PERT cells with passivating contact technology, and have already achieved efficiencies above 23%. Combining all the technology know-how, we are confident that our bifacial n-type solar cells will achieve an efficiency above 24% very soon.”

The latest record was set from a batch of 12 new M2-sized cells (244.3 cm²) measured at ISFH CalTec that showed an average conversion efficiency of 23.0%, with the best cell topping 23.2%. Imec said measurements revealed a bifaciality factor above 80%. 

Measurements taken under standard front illumination conditions in conjunction with an additional 0.15 sun rear illumination, led to effective a conversion efficiency of almost 26%, according to imec. 
ISFH Caltec also measured an average reverse current of -0.4A (at -12V) indicating improvements to the breakdown characteristics of the cells.

Loic Tous, project leader at imec/EnergyVille added, “Compared to the previous results imec reported, we have further optimized the fully screenprinted bifacial n-PERT cell process and adopted a design with twelve busbars. The current cells also have a screenprinted front grid and rear soldering pads that use less silver. The open circuit voltage (Voc) is now above 690mV with fill factors up to 83%. These remarkable results are obtained using the same industry-compatible equipment to produce bifacial p-PERC cells, with the addition of a boron diffusion.”

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