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<br>
My 2 cents worth here says that this PID problem is the same as
the negative ground problem that occurred with the<br>
Sun Power modules that wanted to be positive grounded. Last I
heard, from Sun Power was that they<br>
have basically gotten around that issue and are "ground agnostic"
as either Sun Power or Bill Brooks<br>
says. Transformer-less or non-isolated inverters are used with
an un-grounded PV array and I<br>
think that is what Zachary Strassman is talking about in his
reply to the question.<br>
<br>
I do not see the answer to the question about AC line frequency
ripple though which<br>
would be 120 Hz (US) or 100 Hz for a 50 Hz grid system at the PV
module.<br>
<br>
The ungrounded part makes sense but as far as TL inverters vs.
inverters with transformers,<br>
both topologies should try to keep the PV voltage right at maximum
power point voltage. If they<br>
do that to extract as much energy as possible from the array,
there will be little to no 120Hz or 100Hz<br>
ripple... If the inverter is designed correctly anyway.<br>
<br>
boB<br>
<br>
<br>
<br>
On 12/27/2013 8:39 AM, Drake wrote:<br>
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<blockquote cite="mid:20131227164242.3789FFFC6@che.dreamhost.com"
type="cite">
Hello Wrenches,<br>
<br>
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.
<br>
<br>
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?<br>
<br>
<br>
Thanks,<br>
<br>
<br>
Drake<br>
<br>
<br>
<a moz-do-not-send="true" name="_MailAutoSig"></a>Drake Chamberlin<br>
<i>Athens Electric LLC<br>
OH License 44810<br>
CO License 3773<br>
NABCEP Certified Solar PV <br>
740-448-7328<br>
</i><a moz-do-not-send="true" href="http://athens-electric.com/">http://athens-electric.com/</a>
<br>
</blockquote>
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