My 2 cents worth here says that this PID problem is the same as the
negative ground problem that occurred with the
Sun Power modules that wanted to be positive grounded. Last I heard,
from Sun Power was that they
have basically gotten around that issue and are "ground agnostic" as
either Sun Power or Bill Brooks
says. Transformer-less or non-isolated inverters are used with an
un-grounded PV array and I
think that is what Zachary Strassman is talking about in his reply to
the question.
I do not see the answer to the question about AC line frequency ripple
though which
would be 120 Hz (US) or 100 Hz for a 50 Hz grid system at the PV module.
The ungrounded part makes sense but as far as TL inverters vs. inverters
with transformers,
both topologies should try to keep the PV voltage right at maximum power
point voltage. If they
do that to extract as much energy as possible from the array, there will
be little to no 120Hz or 100Hz
ripple... If the inverter is designed correctly anyway.
boB
On 12/27/2013 8:39 AM, Drake wrote:
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/
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