Imec, Jolywood announce 23.2% front-side conversion efficiency for n-PERT bifacial cell

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From pv magazine Global.

Belgian micro and nanoelectronic research center Imec and Chinese bifacial solar panel maker Jolywood have achieved a 23.2% front-side conversion efficiency for an n-PERT solar cell.

Imec said the result was certified, with 12 M2-sized (244.3 cm²) cells measured by the solar cells laboratory at the calibration and test center (CalTeC) of Germany’s Institute for Solar Energy Research (ISFH). The Belgian research body added, its measurements showed cell bifaciality of more than 80%.

The cells’ effective efficiency was estimated at around 26% after exposing it to standard front illumination conditions together with 0.15-sun rear illumination, Imec scientists said. They said CalTec certified an average reverse current of -0.4 A (at -12 V), which should provide excellent breakdown characteristics.

ISFH partner EnergyVille – a sustainable and intelligent energy collaboration between Flemish research partners KU Leuven, VITO and UHasselt – said the bifacial cells have screen-printed front grid and rear soldering pads that use less silver, and the efficiency landmark was achieved thanks to a new design with 12 busbars.

“The open circuit voltage (Voc) is now above 690 mV with fill factors up to 83%,” said Loic Tous, project leader at imec/EnergyVille. “These remarkable results are obtained using the same industry-compatible equipment [that is used] to produce bifacial p-PERC cells, with the addition of a boron diffusion.”

Advantage n-PERT

Imec researchers wrote: “The developed n-PERT technology has a number of inherent advantages over p-type PERC cell technology, which is demonstrated in these newest cells: the potential for higher efficiencies because of a lower sensitivity to metal impurities and the absence of light induced degradation.”

The Belgian institute and Jolywood said they will now aim for bifaciality of more than 90% and front-side conversion efficiency of 23.5%.

The two entered a partnership to improve n-type manufacturing processes in May. At the time, the partners unveiled a plan to develop bifacial cells with an average frontside efficiency of 21.9%. Imec had previously achieved an average efficiency of 22.04% on its bifacial n-type PERT cells and its cell technology is said to have the potential for a cost-of-ownership at module level of less than $0.30/W (Rs20.87). In particular, Imec cited the limited use of silver along with the potential for multi-wire interconnection schemes as factors that could lead to a low cost production process.