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In this work, we analyse the light and elevated temperature induced degradation (LeTID) behaviour of gallium (Ga)-doped Czochralski (Cz) passivated emitter and rear cells (PERC). We show that these cells, based on industrial precursors, are prone to LeTID, degrading on average 8.3% rel in efficiency. The degradation and regeneration is slower than in boron (B)-doped PERC cells leading to a greater loss of energy over a 20 year lifespan of a solar module on a German rooftop, since, according to our experiments, regeneration does not start during that time frame. We show that the method of mitigating LeTID by slightly altering the temperature profile during fast firing, previously introduced on B-doped PERC cells, also works on Ga-doped PERC cells, reducing the maximum degradation to between 1% rel and 4% rel. This process does only slightly reduce the initial efficiency of the cell by up to 0.8% rel. Lastly, we show that increasing illumination and temperature from 0.15 suns eq. to 2 suns eq. and 75 °C to 140 °C, respectively, is an adequate way to accelerate LeTID testing on Ga-doped samples by more than two orders of magnitude while achieving qualitatively and quantitatively similar results to those obtained in a standard test. • Ga-doped PERC cells made from industrial precursors can show severe LeTID-degradation. • LeTID can be mitigated by adapting FFO firing profile. • This process can be implemented at relatively high belt speeds. [ABSTRACT FROM AUTHOR]

Light- and elevated temperature-induced degradation (LeTID), which can lead to significant module power loss in the field, has been extensively studied for boron (B)-doped silicon solar cells in the past. Current mass-production has shifted to gallium (Ga)-doped silicon substrates. Therefore, process influences on LeTID must be re-investigated for the changed acceptor species, as the LeTID-degradation extent and kinetics can be drastically different. We study the influence of the dielectric layer and the firing profile on the LeTID extent in Ga-doped lifetime samples. Furthermore, the effect of the bulk doping concentration is investigated. We find that a dielectric layer with high hydrogen content, a-SiN x :H (PECVD), leads to largest LeTID degradation. However, AlO x (PECVD) interlayers serve as very effective diffusion barriers, thus mitigating LeTID, as expected from studies on B-doped material. We observe no significant dependence of LeTID susceptibility on the doping concentration. Most interestingly, it appears that modifying the peak firing temperature, which has the greatest effect on the extent of LeTID in B-doped silicon, has a much smaller effect on the Ga-doped material, with LeTID being observed even when firing at 700 °C. • Ga-doped lifetime samples can show severe LeTID-degradation. • LeTID can be mitigated by adapting passivation layer and/or FFO firing profile. • Increasing temperature and illumination accelerates LeTID tests by a factor of 1000. [ABSTRACT FROM AUTHOR]