SB's in high temperature (was lemmings) [RE-wrenches]

[Joel Davidson]

Dear John,
I am glad you are working on the inverter power rating issue. I hope it
doesn't take as long to get inverter standards at it is taking to get PV
module standards. Chuck Whitaker's January 1998 "PV Module Energy Rating
Procedure" report that starts, "In May 1994, NREL initiated an effort to
develop a consensus-based approach to rating PV modules." Here it is eight
years later and still no PV module energy rating procedure. If you'd like to
share the preliminary inverter rating standards, some of us designers will
start using them before waiting for their formal adoption.
Best regards,
Joel Davidson

jberdner at sma-america.com wrote:

> Joel:
>
> UL established the power rating our inverter at 2500 Watts.
> You can certainly design the system around 2200 Watts and it will run
> just fine.
>
> I am a member of the Standards committee at UL and we are proposing
> changing to UL 1741 the way power ratings are established to make power
> rating better reflect real world conditions.  This will give us a level
> playing field for inverter power ratings (for both grid tied and off
> grid) that better reflects the needs of customers.
>
> 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, February 06, 2003 3:05 PM
> To: RE-wrenches at topica.com
> Subject: Re: SB's in high temperature (was lemmings) [RE-wrenches]
>
> John,
> I think you will sell just as many Sunny Boy inverters if you rate them
> 2.2
> kW instead of 2.5 kW.
> Best regards,
> Joel Davidson
>
> jberdner at sma-america.com wrote:
>
> > Graham:
> >
> > While you can use the Sunny Boy + Breeze scenario there is another
> more
> > conservative approach is reliability and longevity are of paramount
> > concern.
> > If you undersize the array by 10 to 15% there should be no issue at
> 103
> > F.  This approach adds no additional hardware and not pushing the
> > inverter to its limits will certainly extend it's life. There is a
> rule
> > of thumb in power electronics (I forget who's rule it is) - for every
> > 10C decrease in temperature the life is doubled. This is true for all
> > power electronics not just our inverters.
> >
> > Fan Life - In building the Sunny Breeze we selected a fan with 30 k
> > hours MTBF.  The 2 to 3 year estimate for life is out estimate for
> > outdoor, unprotected mounting.  If mounted indoors it will run more
> > frequently but the life of the fan should certainly be well beyond the
> > warranty period.
> >
> > 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)
> >
>
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