[RE-wrenches] PID

[Steven Lawrence]

Hi Drake,
There are a few papers that go into PID, including one form SMA (simple
google search).

http://solarenergy.advanced-energy.com/upload/File/White_Papers/ENG-PID-270-01%20web.pdf
http://files.sma.de/dl/7418/PID-PVOBox-TI-en-10.pdf

In short, it mostly depends on the module construction and whether or not
it's installed correctly (like the article said, negatively grounding old
Sunpower modules do not fare well, nor do positively grounded Evergreen
modules).  Be sure to ask your module manufacturer for their information on
PID, but I believe all Tier 1 module manufacturers do not have
any significant PID.  Even if they did, you could argue that it should be
covered under the module performance warranty.

Also, let's not confuse ungrounded PV systems with transformerless
inverters.  The formerly known as Solaron inverters are transformless and
still uses a grounded conductor.  The SMA CP-US inverters are transformless
and can use a solidly grounded conductor.

-Steven Lawrence

>
>
> Hello Wrenches,
>
> Attached is an article from Home Power that came in my email. It says
> module degradation is increased by PID (Potential Induced
> Degradation) by the use of transformerless inverters.  It says power
> degradation can occur over days or weeks and cause a 10% to 60% loss
> of efficiency.
>
> I called Power One and SMA and their tech support people have not had
> any reports of problems. Is this something we need to be concerned about?
>
>
> Thanks,
>
>
> Drake
>
>
> Drake Chamberlin
> Athens Electric LLC
> OH License 44810
> CO License 3773
> NABCEP Certified Solar PV
> 740-448-7328
> <http://athens-electric.com/>http://athens-electric.com/
>
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