Chinese module manufacturer Longi has received TÜV SÜD certification for its Hi-MO 9 and Hi-MO X10 HPBC 2.0 back-contact modules, in accordance with standards PPP 58234A:2025 and IEC TS 62804-1 Ed2, for their resistance to polarisation-induced degradation (PID-P). According to Longi, these are the first modules to receive this certification.
PID-p is a type of performance degradation caused by voltage, which occurs when the electric field generated by the system voltage causes polarization effects in the passivation layer of silicon cells. While performance losses due to PID-p are reversible, they develop more quickly than other irreversible voltage-induced degradation mechanisms, according to Longi. Due to its growing significance, PID-p has attracted the attention of technical standardisation bodies such as the IEC, as well as research institutions such as NREL. In the TÜV SÜD testing process, real-world stress conditions are simulated by combining voltage, temperature, and light exposure in order to evaluate the durability of modules under polarisation stress.
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