Thanks, first time I'm hearing about this. I'm looking at LG NeON 2 360W panels - found some brochures saying they've "anti-PID." Still trying to figure out how big of a worry this is though. Check out
https://www.photovoltaik4all.de/media/pdf/28/75/4c/LGE-PID-White-Paper-v1-1.pdf for example.
Looks like SMA makes a "PV Offset Box" - it's installed ground level so I can add it later if this becomes a worry.
And this paper from SMA says, using PV Offset Box helped the PV panels but increased chance of damage to inverter.
Dated 2016, it recommends use only with newer (as of then) SMA inverters, not older models like I have. Don't know the situation regarding current models, I looked but no mention in the manuals or literature on the product page. Ideally it would be a built-in feature that could be enabled.
"Modules touted as being PID-free are anything but PID-free, as shown by this comparison test on modules from four different manufacturers for test periods of 168 (procedure 1) and 336 hours. The manufacturers are grouped by identical colors: manufacturer 1 and manufacturer 2 have claimed to be “PID-free.” It is interesting to note that for manufacturer 1, from which two batches were tested, there is a significant difference between modules. The modules with the worse results had degraded by more than 50% after the first test step. There is also a significant difference between modules from manufacturer 2, but this was not visible until the second week of testing. The dotted line indicates the 5% pass/fail criterion typically used in photovoltaics."
Potential-induced degradation: Even though many module manufacturers are now promoting PID-resistant modules, the problem of potential-induced degradation remai
www.vigdu.com
Also says, "Without moisture and dirt, there is little chance of PID occurring." I think that is because dirt and moisture on panel serve as an electrode, applying ground potential over face of panel.
"Due to moisture and impurities, a conductive layer is produced on the front of the glass. Through this, potential builds up between the glass and the solar cell, generating a small current as sodium (Na+ ) ions move from the glass toward the cell. On the front of the solar cell, these sodium ions create an accumulation of positive charges, which then cause short-circuiting (shunting) in the solar cell."
"PID can be reversed in certain cases by applying an opposing potential to counter the damage-inducing potential. For this reason, it would be a reasonable strategy to move the modules around in the string at regular intervals, such that the degraded modules can be regenerated. This is extremely time-consuming."
With a transformerless inverter, half the panels are above ground potential, and half below. If assigned to three or four groups, using extension cables they could be rotated through different orders of connection so they spend some time biased above ground, some time below. So much bother, though. And it only addresses the reversible portion of degradation.