The Chinese manufacturer brings the efficiency of heterojunction silicon photovoltaics to 26.30%. The highest value ever achieved in the world
What are HJT solar cells?
(Rinnovabili.it) – Only three days and the world record for HJT solar cells, reached on October 26, is already old. To overcome it, however, is the same creator of the first. Let’s talk about the Chinese manufacturer Longi that, in a continuous race to optimize its products, stands constellating this 2021 with firsts.
The researchers of the group managed to go from a conversion efficiency of 25.82 percent to one of 26.30 percent in just a few days. The technology in question is that of heterojunction silicon photovoltaic or HJT. It is a special PN junction, which combines two different solutions into one unit: one moncrystalline silicon cell inserted between two thin films of amorphous silicon. This mix ensures both greater energy harvesting and better functionality for the double-sided modules. In addition to boasting fewer stages in the production process than a traditional solar cell.
The new conversion value achieved by Longi also represents the highest efficiency in the world for a solar cell Front-Back Contact (FBC). And, as with the previous benchmark, the record was validated by independent tests from the Institut für Solarenergieforschung (ISFH) in Germany.
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“The fill factor FF (ratio between the ratio between the maximum output power and the ideal one) […] exceeded the 86% threshold, reaching 86.59% “, explains the company. “The highest level in the world for silicon cells. A new process developed by our R&D team can effectively reduce the contact resistance of the interface, so as to improve the FF and increase the cell current density “. The latter value reached 40.49 mA / cm².
Compared to the previous HJT solar cells, the new units have some optimizations. The N microcrystalline window layer has been enhanced to further increase current density, with a new intrinsic layer structure developed to improve passivation performance and increase Voc (open circuit voltage) up to 2mV. The LONGi team also applied some transparent conductive oxides completely free of indium.
“From 25.26% to 25.82% up to the last 26.30%. LONGi has now achieved the rare feat of setting world efficiency records for HJT solar cells three times in six months ”.
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