The issue of Light and elevated Temperature Induced Degradation (LeTID) is affecting mostly high-efficient PERC cells, but what is LeTID and why is it happening at high-efficient PERC p-type cells mostly?
What is Light and elevated Temperature Induced Degradation (LeTID)?
According to Fabian Fertig and et al. research, besides the well-known LID of excess charge carrier lifetime within Czochralski-grown silicon substrates induced by the activation of the boron-oxygen complex, significant performance degradation has been observed also for certain p-type PERC silicon solar cells and modules.
The syndrome of LeTID for PERC p-types
After exposing p-type PERC solar cells for the first time to the sunlight, there is a sudden loss in the PV module performance. Light and elevated Temperature Induced Degradation (LeTID) and LID are the main reason for this loss in the performance. These losses are also known as degradations and showed in the guaranteed power performance chart of the modules.
A Possible Solution
Recently, LONGi Solar is employing gallium-doping technology to reduce PID and LeTID related degradations. Banking on this doping technology, LONGi promises to keep the first-year degradation below 2%, while the actual value is about 1%.
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