SWR2500U Some derating likely [RE-wrenches]

Fri Nov 22 13:59:01 PST 2002

Joel:

Use 20 140's if you want to keep it simple.

If you have any questions, or if I can be of any further assistance,
please do not hesitate to contact me.

Best Regards,

John Berdner

SMA America, Inc.
12438 Loma Rica Drive, Unit C
Grass Valley, CA  95945
530.273.4595 (voice)
530.274.7271 (fax) 

-----Original Message-----
From: Joel Davidson [mailto:joeldavidson at earthlink.net] 
Sent: Friday, November 22, 2002 11:15 AM
To: RE-wrenches at topica.com
Subject: Re: SWR2500U Some derating likely [RE-wrenches]

Dear John,

1. Let's keep it simple. Use PVUSA PTC conditions:
Wind speed at 1 m/second at 10 meters above grade.
Irradiance at 1000 watts/m2.
Ambient temperature 20 degrees C.

2. One of the nice things about the Sunny Boy inverter is no fan. Let's
keep
it that way as much as possible.

Happy Thanksgiving,
Joel Davidson
"You can lead a horse to water, but you can't make it drink. You can
send a
man to Congress, but you can't make him think."

jberdner at sma-america.com wrote:

> Joel:
>
> As Mo pointed out it is all about airflow.
> This is why it is difficult for us to quantify exactly when and how
much
> derating at what power level.
>
> How much does the wind blow ?
> How much does the sun shine ?
> How hot does it get and when ?
>
> These are all critical variables that are up to Ma Nature.
> Beyond that we can only go with experience (2.8 to 3 kW STC max) and
> provide solutions, i.e. a fan, when we are wrong.  What I can say
> conclusively is: a 12 Vdc 3" muffin fan, running at 9 Vdc, draws about
> 1.5 Watts, is virtually silent, and  drops the heatsink temperature by
> about 15 C.  This simple solution is enough to solve any derating
issue
> we have seen to date.
>
> If you have any questions, or if I can be of any further assistance,
> please do not hesitate to contact me.
>
> Best Regards,
>
> John Berdner
>
> SMA America, Inc.
> 12438 Loma Rica Drive, Unit C
> Grass Valley, CA  95945
> 530.273.4595 (voice)
> 530.274.7271 (fax)
>
> -----Original Message-----
> From: Joel Davidson [mailto:joeldavidson at earthlink.net]
> Sent: Thursday, November 21, 2002 6:36 PM
> To: RE-wrenches at topica.com
> Subject: Re: SWR2500U Some derating likely [RE-wrenches]
>
> Mo,
> Thanks for the solid feedback!
> Joel Davidson
>
> Mo Rousso wrote:
>
> > I know Joel is looking for some hard data, but I can only offer my
> > observations.
> >
> > We installed 24 BP MSX-120 (12VDC nom) on 1 SB 2500 on an open
> southern
> > exposure roof with a pitch angle of 18 degrees.  The owner wanted to
> push
> > the inverter to the max and we added a 25th panel to the string.
> >
> > The inverter is mounted on an interior south facing wall of the
garage
> > (please don't yell at me John!!!) in Fallbrook, CA.
> >
> > On those days when we had nice bright skies and cool temps the
> inverter
> > would go into derate mode.  However, we added a fan to the heat sink
> and the
> > derate issue has been completely eliminated.  The customer is
getting
> every
> > erg he can out of the set-up and is now a happy camper.
> >
> > I decided to add a fan to my SB to see what would happen.  My home
has
> 20 BP
> > 2150s modules with 10 modules per pole on DP&W TPM racks.  Both
poles
> feed a
> > single SB2500.  In the past, I would occasionally  see derates maybe
> 20
> > times per year for a 1 to 2 hour period each.  The fans I mounted
are
> DC and
> > are powered by a 10W PV module that is oriented so that it powers up
> the
> > fans around 10 AM until dark.  All deratings have ceased and I have
> actually
> > seen my SB display post an output reading of 2507 watts.
> >
> > My goal is to build a small DAQ system and actively log my system
> > performance so that I have hard data to analyze.  Until then, if
> derating is
> > an issue, put on a fan - it works.
> >
> > Mo
> > --
> > Mo Rousso
> > HelioPower
> > Renewable Energy Systems
> > Remote Power Solutions
> > mrousso at heliopower
> > www.heliopower.com
> > 760.845.8843
> >
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