On 3/21/2013 9:59 PM, Exeltech wrote:
Wrenches,
I'm probably a lone voice on this .. and not intending to get overly
picky.
No, two lonely voices, Dan.
I associate clipping with audio waveforms which stops
the negative or positive voltage peaks flat. Also called
flat-topping.
Limiting is like turning down the volume. The waveform
stays the same and does not distort as it would if it
were being flat topped (and flat bottomed)
Thanks !
boB
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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