[RE-wrenches] P1 micro performance

[boB]

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.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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