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<div class="moz-cite-prefix">On 3/21/2013 9:59 PM, Exeltech wrote:<br>
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<td style="font: inherit;" valign="top">Wrenches,<br>
<br>
I'm probably a lone voice on this .. and not intending to
get overly picky.<br>
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No, two lonely voices, Dan.<br>
<br>
I associate clipping with audio waveforms which stops<br>
the negative or positive voltage peaks flat. Also called<br>
flat-topping.<br>
<br>
Limiting is like turning down the volume. The waveform<br>
stays the same and does not distort as it would if it<br>
were being flat topped (and flat bottomed)<br>
<br>
Thanks !<br>
boB<br>
<br>
<br>
<br>
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<td style="font: inherit;" valign="top"><br>
Could we call power limiting what it is .. "limiting", and
not "clipping"?<br>
<br>
Clipping implies distortion, which isn't the case here.
Limiting is just that.<br>
The inverter output is limited to some maximum value --
not "clipped".<br>
<br>
The output power curve flattens when integrated over time,
but this still isn't<br>
distortion in the waveform. It's simply a point in the
output where the derivative<br>
is zero. Not increasing, not decreasing. Just .. zero.
No additional increase<br>
in the output for an increase in available energy at the
input. Think "governor"<br>
on an engine....<br>
<br>
Thanks.<br>
<br>
<br>
Dan Lepinski, Sr. Engineer<br>
Exeltech / Exeltech Solar Products<br>
<br>
<br>
--- On <b>Thu, 3/21/13, David Brearley <i><a class="moz-txt-link-rfc2396E" href="mailto:david.brearley@solarprofessional.com"><david.brearley@solarprofessional.com></a></i></b>
wrote:<br>
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From: David Brearley
<a class="moz-txt-link-rfc2396E" href="mailto:david.brearley@solarprofessional.com"><david.brearley@solarprofessional.com></a><br>
Subject: Re: [RE-wrenches] P1 micro performance<br>
To: "RE-wrenches"
<a class="moz-txt-link-rfc2396E" href="mailto:re-wrenches@lists.re-wrenches.org"><re-wrenches@lists.re-wrenches.org></a><br>
Date: Thursday, March 21, 2013, 11:37 PM<br>
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<div>Thanks for sharing the screen capture, Marco.</div>
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<div>Interesting issues to think about here. This is
actually prime clipping season in many places (not
sure about Hawaii) due to the cool weather. While
there are more sun-hours in the summer, the cell
temperatures are often high enough that you won't
tend to see rated power out of the modules. </div>
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<div>While I'm not running performance models for
work, the people who do are routinely increasing
dc-to-ac ratios, often as high as 1.4-to-1. Having
said that, most inverters aren't installed on a
roof. (Not yet anyway.) </div>
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<div>I'd probably lean to a more conservative sizing
ratio for micros. While I can imagine some
scenarios where I'd be comfortable with a 215 W
micro on a 265 W module—like a flat roof install
in Vermont, which reportedly doesn't see 1,000
W/m^2 very often—I wouldn't try that here in
Texas.</div>
<br>
<br>
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