37th EU PVSEC, 07 - 11 September 2020

04 February 2019

Higher & Higher: The Year Starts With Solar Efficiency Improvements Across the Board

The PV industry continues to make progress on all fronts. Not only are global solar installations expected to grow significantly this year (see EU PVSEC Blog), solar cell efficiencies are key enablers to lowering costs for solar power as well. And in the last two months there were several impressive announcements for efficiency improvements of different cell technologies.

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Look at heterojunction technology (HJT), one of the most promising high-efficiency solar cell candidates these days. The French research institute CEA achieved a 23.9% conversion efficiency for a HJT PV cell. The significance of this efficiency level is that it has been attained on a standard wafer size in an industrial environment using HJT production equipment supplied by Swiss company Meyer Burger. The CEA team manufactured 5-busbar cells on equipment that can support an hourly throughput of 2,400 cells an hour. It achieved the 23.9% efficiency over the whole surface of a standard size solar cell (244 cm²). Germany’s CalTec-ISFH certified the efficiency.

PERC, which stands for Passivated Emitter Rear Cell (PERC), has not only become the new standard for monocrystalline solar cells, this technology has also become the subject of an efficiency race of PV cell and module manufacturers. LONGi Solar has announced a 24.06% conversion efficiency for its bifacial monocrystalline silicon PERC cell based on a commercial wafer size. The integrated PV manufacturer claimed back the crown from another Chinese company JinkoSolar, which attained 23.95% in May 2018 using selective emitters and an advanced passivation scheme, superseding LONGi’s February 2018 announcement of 23.6%. While the results are very impressive, in particular regarding the large size, such record PERC cells use special features that won’t be seen in production anytime soon.

The same is true for the remarkable thin-film record from Solar Frontier. The Japanese company announced a new world record solar cell conversion efficiency for copper indium selenium (CIS) technology. Solar Frontier produced a 23.35% conversion efficiency for a 1 cm² lab-size thin-film solar cell using its CIS technology that was verified by AIST.

As solar researchers are making remarkable progress in improving efficiencies of single-junction crystalline solar cells and are getting closer to the theoretical efficiency for that cell design of around 30%, they are also already working on third-generation PV technologies that involve multiple-junction crystalline silicon cell-based architectures. Fraunhofer ISE has reported a new efficiency record of 22.3% for a III-V/Si tandem cell architecture. The German research institute underscored that the III-V layers were directly grown on the silicon in collaboration with German equipment maker Aixtron SE, the Philipps University of Marburg and Technical University Ilmenau.

Perovskite is another interesting candidate for silicon-based tandem cell structures. In December, Arizona State University & University of Nebraska-Lincoln announced a 25.4% efficient perovskite-silicon tandem solar cell. The researchers attribute the performance leap from the previous level of 23.6% to the new chemicals additions to the precursor solution. About a week before, UK based Oxford PV achieved 28% power conversion efficiency for its perovskite solar cells, beating its previous record of 27.3% for a perovskite-silicon solar cell announced in June 2018. This record efficiency was attained on a 1 cm2 cell and was certified by NREL.

For certain applications it make economic sense to use also very high efficient III-V semiconductors exclusively. Alta Devices, the US subsidiary of China’s Hanergy Thin Film Power Group, has reached 29.1% efficiency for its single-junction GaAs solar cell technology. The efficiency was certified by Fraunhofer ISE CalLab.

If you are working on any such interesting technology that comes with a promise of improving the output power of a solar cell device of any class, section or category, the 36th EU PVSEC - taking place in September in Marseille, France - provides the perfect platform to share your research results with the PV scientific community. You are invited to submit your solar research abstracts by 8 February 2019.