Ultraviolet Induced Degradation

Kiwa PVEL’s ultraviolet induced degradation (UVID) test goes beyond standard IEC/UL certification to identify modules that are susceptible to this degradation mechanism. HJT and TOPCon modules are advertised to have improved first year and annual degradation rates, but examples of both (in addition to PERC) have shown significant UV-induced power loss. While the test duration is not necessarily sufficient to reach the maximum amount of degradation resulting from UVID, this test is able to distinguish between UVID- susceptible and UV-stable modules.

Key
Takeaways

The degradation following 120 kWh/m2 of UVID ranged from 0.6% to 16.6%.

The median and average UVID power loss across 10 BOMs tested was 2.2% and 3.5%, respectively, with only half of the BOMs tested having less than 2% degradation. Considering 120 kWh/m2 is only representative of 6~24 months of outdoor exposure (depending on location), these initial UVID results raise significant concerns for module warranty compliance.

Test Result Spotlight

Since introducing the UVID test as part of the updated PQP in November 2023, Kiwa PVEL has started to identify commercially available BOMs that suffer significant degradation following UV exposure. In this example, the power loss was just over 5% following a 60 kWh/m2 UV dose and exceeded 12% following 120 kWh/m2. The EL images of UV-susceptible modules typically exhibit a ‘checkerboard’ pattern that is also seen in LETID-susceptible modules, indicating that cells are not uniformly affected by UVID stresses.