Hi Dan,
A very heartfelt thanks for the education.
It is exactly this kind of attention to detail that separate the
professional from the practitioner. Moreover, at least in this case, the
proper terminology is hopefully better and more widely understood.
Thanks again,
Bill Loesch
Solar 1 - Saint Louis Solar
314 631 1094
On 21-Mar-13 11:59 PM, Exeltech wrote:
Wrenches,
I'm probably a lone voice on this .. and not intending to get overly
picky.
Could we call power limiting what it is .. "limiting", and not "clipping"?
Clipping implies distortion, which isn't the case here. Limiting is
just that.
The inverter output is limited to some maximum value -- not "clipped".
The output power curve flattens when integrated over time, but this
still isn't
distortion in the waveform. It's simply a point in the output where
the derivative
is zero. Not increasing, not decreasing. Just .. zero. No additional
increase
in the output for an increase in available energy at the input. Think
"governor"
on an engine....
Thanks.
Dan Lepinski, Sr. Engineer
Exeltech / Exeltech Solar Products
--- On *Thu, 3/21/13, David Brearley
/<david.brear...@solarprofessional.com>/* wrote:
From: David Brearley <david.brear...@solarprofessional.com>
Subject: Re: [RE-wrenches] P1 micro performance
To: "RE-wrenches" <re-wrenches@lists.re-wrenches.org>
Date: Thursday, March 21, 2013, 11:37 PM
Thanks for sharing the screen capture, Marco.
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.
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.)
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.
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