SB Disco for 2 strings (was RE: ST XR series, anyone tried on yet? ) [RE-wre
mrousso at urbanrefuge.com
mrousso at urbanrefuge.com
Fri Jun 21 14:20:24 PDT 2002
Those look good. Also, an Outback PSSB with a
combiner box front-end would be useful. This could
also provide an AC disco option to boot.
Thanks!
Mo
--- "Brian C. White" <brianw at connectenergy.org>
wrote:
> Mo,
>
> Take a look at Connect Energy's PCBHV4D, I think we
> may have the
> disconnect you are describing.
>
> Contact me off list if you have questions
>
> Brian C. White
> Mechanical Design / Technical Sales
> Connect Energy
> www.connectenergy.org
>
> If I can be of further help, please contact me
> directly.
> 530-271-1919 x.106
> brianw at connectenergy.org
>
>
> mrousso at urbanrefuge.com wrote:
> > In my opinion a really nice dc disco would also
> have a
> > combiner box built in. So, if you are running two
> > strings of 24vdc panels you can combine them
> before
> > the SB, provide string fusing, and have only a
> single
> > disco to contend with. Is my thinking flawed --
> any
> > other suggestions?? We are doing quite a bit of 2
> > string installs with a single SB.
> >
> > Thanks!
> > Mo
> > --- jberdner at sma-america.com wrote:
> > > William:
> > >
> > > Two of our customers have been testing the new
> XR's
> > > which are
> > > replacements for older ST's.
> > > They both tell me they are better than the ST in
> > > steady state conditions
> > > (clear sky) but still have trouble if there are
> any
> > > clouds in the sky.
> > > This is really key since we don't all have
> perfectly
> > > clear sky days.
> > > The MPPT seems to get lost if the irradiance is
> > > changing.
> > > Now the XR's are only 10 to 15% behind the Sunny
> Boy
> > > instead of 20 to
> > > 25% for the older ST's.
> > > 10% does not seem like much but would you
> seriously
> > > consider an inverter
> > > that was 80 to 85% efficient instead of one that
> was
> > > 94.4 ?
> > > By the way - I use 92.5% for design by the way
> not
> > > 94.4 peak as in the
> > > CEC calculation
> > >
> > > To address the comment re: internal disconnects.
> > > We tried to put one in but we can't' get a
> > > conclusive go ahead from UL.
> > > The inverters are considered serviceable items
> and
> > > therefore you have to
> > > be able to remove it form the installation and
> leave
> > > things in a safe
> > > condition.
> > > Right now this means an external disconnect
> until UL
> > > says otherwisw.
> > > I know the ST /XR does it but that does not mean
> we
> > > want to do it too.
> > > We operate at higher voltages and I want to be
> safe
> > > rather than sorry.
> > > I am working on lower cost disconnects and will
> let
> > > you know when we get
> > > one.
> > >
> > > 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.
> > > 20830 Red Dog Road
> > > Grass Valley, CA 95945
> > > 530.273.4595 (voice)
> > > 530.274.7271 (fax)
> > >
> > >
> > > -----Original Message-----
> > > From: William Miller
> [mailto:wrmiller at slonet.org]
> > > Sent: Thursday, June 20, 2002 9:32 PM
> > > To: RE-wrenches at topica.com
> > > Subject: Re: ST XR series, anyone tried on yet?
> > > [RE-wrenches]
> > >
> > > Bob-o:
> > >
> > > We used to joke that the person who recommended
> the
> > > meters on the ST was
> > > bound to get fired. I guess he or she did get
> > > fired.
> > >
> > > I am not impressed that the STs no longer have
> the
> > > metering we were used
> > > to. I thought this was one of only two
> advantages
> > > the ST had over the
> > > Sunny Boy (the other is built in disconnects).
> > >
> > > Also, it sounds like you are assuming the
> shut-downs
> > > are caused by grid
> > > problems. Do you have evidence of that? (After
> > > watching the original
> > > ST
> > > inverters shut down hundreds of times, I am
> > > convinced it was because the
> > > MPPT algorithm was too aggressive and, after
> loading
> > > the panels too
> > > much,
> > > the voltage collapsed. You could see the PV
> volts
> > > cave just before the
> > > shutdown.)
> > >
> > > I did a back-to-back comparison between the
> > > original ST2500 and the
> > > SB2500
> > > and found the ST to be about 10% less efficient
> than
> > > the SB. Sounds
> > > like
> > > we may be in the same ballpark. This comparison
> was
> > > relevant for the
> > > periods of time that the ST was running.
> Frequent
> > > shut-downs and the
> > > subsequent time-outs could reduce the efficiency
> > > significantly.
> > >
> > > This was actually a trick question as I
> installed
> > > two XRs yesterday, but
> > > wanted to reserve judgement until I heard from
> > > others. One of my two
> > > inverters had a missing lower line on the
> display.
> > > This was also
> > > disappointing as I have many of display failures
> in
> > > the original STs.
> > >
> > > I'm looking for a reason to use STs rather than
> > > Sunny Boys and I haven't
> > > found one yet. With the SB1800s now shipping
> (they
> > > are shipping, aren't
> > > they?) the 1500 no longer fills any kind of gap
> in
> > > the product line.
> > >
> > > Thanks for your responses,
> > >
> > > William Miller
> > >
> > >
> > >
> > > At 10:20 AM 6/20/02 -0700, you wrote:
> > > >William,
> > > >We probably ARE all fiends, at that!
> > > >I've got six of the STXR 2000 in parallel on a
> big
> > > system in Redding.
> > > >We had a few fits and starts, but at this point
> > > they all seem to be
> > > >playing nicely. I'm seeing about 65-68%
> conversion
> > > from PV nameplate
> > > >watts to ac watts out. That's about 10% less
> than
> > > the Sunny Boy will
> > > >give you, but you've got to figure that 48V to
> 240V
> > > step up is going
> > > >to be less efficient anyway.
> > > >Roy,
> > > >Yes, the meter built into the XR shows
> cumulative
> > > DAILY watts (resets
> > > >every night) ONLY. If you want instantaneous
> watts,
> > > volts, etc., you
> > > >have to have the STXR remote. Xantrex claims
> that
> > > they changed the
> > > >display because they were getting too many
> calls
> > > from end users
> > > >reading it and being confused. Yeah, yeah...
> maybe.
> > > On the other
> > > >hand, Xantrex is a MARKETING company, so....
> > > >One cool thing about the remote is the error
> codes
> > > feature. It will
> > > >tell you how many times the inverter has gone
> off
> > > line for 5 minutes
> > > >due to poor grid voltage, frequency,
> overheating,
> > > etc. It's amazing
> > > >how often that happens. So much for grid
> stability.
> > > Unfortunately,
> > > >the codes are not resettable to zeros (dumb) so
> you
> > > have to keep a
> > > >running tally from looksee to looksee.
> > > >Bob-O
> > > >
> > >
> > >
> >
>
__________________________________________________________________
> > > William Miller
> > > Miller Power and Communications
> > > PO Box 50, Santa Margarita, CA 93453
> > > Voice :805-438-5600 Fax: 805-438-4607 VMail:
> > > 805-546-4875
> > > email: wrmiller at slonet.org
> > > http://millerpowerandcomm.com
> > > License No. C-10-773985
> > >
> >
>
_____________________________________________________________
> > > Compatibility:
> > > Word processor: WP7
> > > Spreadsheet: Quatro Pro 7
> > > CAD: Microstation 95, DXF, Visio 4.1T
> > >
> >
>
_____________________________________________________________
> > > "Every decent man is ashamed of the government
> he
> > > lives under."
> > > H. L.
> Mencken
> > >
> >
>
__________________________________________________________________
> > >
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> >
> >
> > =====
> > Mo Rousso
> > Urban Refuge, Inc.
> > 760.451.9374 (v) 760.451.9784 (f)
> > mrousso at urbanrefuge.com
> > www.urbanrefuge.com
> >
> > __________________________________________________
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> >
> >
>
>
>
> Brian C. White
> Mechanical Design / Technical Sales
> Connect Energy
> www.connectenergy.org
>
> If I can be of further help, please contact me
> directly.
> 530-271-1919 x.106
> brianw at connectenergy.org
>
> - - - -
> To send a message: RE-wrenches at topica.com
>
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>
> List rules & etiquette:
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>
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>
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>
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>
>
>
=====
Mo RoussoUrban Refuge, Inc.760.451.9374 (v) 760.451.9784 (f)mrousso at urbanrefuge.comwww.urbanrefuge.com
__________________________________________________
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