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Potential Induced Degradation 
PID results improved over the past year, with 82% of BOMs produced in 2025 having <2% power loss following PID(-). But PID remains a relevant reliability concern with 15% of PID BOMs suffering a PID failure and one BOM exhibiting non-recoverable PID power loss >20%.
71%
BOMs are PID Top performers
144
Manufacturers are PID top performers
15%
of BOMs had a PID failure
The PQP’s Potential Induced Degradation (PID) test doubles the IEC/UL certification test duration to 192 hours. PID occurs primarily in electrically ungrounded PV systems with high voltages, especially those using transformerless inverters. Of the different forms of PID, PID-shunting occurs when sodium ions from the glass travel to pinholes in the anti-reflective coatings on the cells, permanently lowering performance. While PID-polarization is static charge build-up due to internal circuit voltages, and is possibly reversible.
Key Takeaways
Less power loss
83%
of BOMs produced in 2025 degraded by <2% following PID(-).
This is an increase from the 72% of BOMs produced in 2024 that degraded by <2%, and represents a statistically significant change. The median degradation following PID(-) decreased from 1.5% for BOMs produced in 2024 to 1.1% for BOMs produced in 2025. The average PID(-) power loss also improved. See the Power Degradation graph below for more.
Failures persist
15%
of BOMs experienced at least one PID failure
Failures detected during PID testing included 6% of PID BOMs experiencing a power loss failure, 5% of PID BOMs experiencing a delamination failure, 2% of PID BOMs experiencing a safety failure, and 1% of PID BOMs experiencing a failed bypass diode. See the Failures page for more.
PID polarization
83%
of PID power loss failures were due to PID-polarization
Five out of the six BOMs with PID power loss failures were affected by PID-polarization. While this degradation is typically reversable following a short UV exposure, there have been reports of PID-polarization occurring in the field under certain site conditions.
PID(-) versus PID(+)
82%
of BOMs have higher negative-polarity PID than positive-polarity PID.
There was only one BOM in the 2026 Scorecard dataset with <2% degradation for PID(-) and ≥2% degradation for PID(+), stopping it from being a Top Performer. Conversely, 18% of BOMs with <2% degradation for PID(+) had ≥2% degradation following PID(-).
PID Test Result Spotlight
Despite PID-shunting (PID-s) being a well-known failure mode, cases of PID-s continue to be seen on some BOMs. One recent BOM exhibited particularly high PID-p power loss (>20%) following PID192(-), mainly driven by fill factor losses. Notably, the performance degradation under low irradiance was even worse, at almost 30%. Post-PID192(-) EL images showed a 'checkerboard' pattern accompanied by intensified edge darkening. The manufacturer submitted new PQP samples for a PID retest and achieved <2% following PID192(-). This demonstrates that strong quality control of cells is both possible and necessary to ensure suitable PID resistance.
Initial
Post-PID192(-) - 21.7% power loss
The initial image shows no indication of PID susceptibility, but after 192 hours of PID(-) testing, most cells show significant darkening due to an accumulation of PID-shunting. Click on each image to see the corresponding full-size EL image.
Power Degradation of PID(-) BOMs
All 2013/2014 and 2015 results are from 600 hours of PID testing. This was decreased to 192 hours for 2016 results and beyond. Only PID-negative results are shown.
Outliers with >10% degradation are not shown. In some cases, these cause a significant reduction in the mean.
See Potential Induced Degradation Top Performers
Click here to see the 150 BOMs listed as PID Top Performers →The PID test procedure, what PV module materials are assessed, and a case study on why PID is important can be found here on kiwa.com/pvel
