[RE-wrenches] P1 micro performance

[Bill Loesch]

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.brearley at solarprofessional.com>/* wrote:
>
>
>     From: David Brearley <david.brearley at solarprofessional.com>
>     Subject: Re: [RE-wrenches] P1 micro performance
>     To: "RE-wrenches" <re-wrenches at 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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