ST XR series, anyone tried on yet? [RE-wrenches]

Kent Sheldon kentsheldon at sbcglobal.net
Mon Jun 24 11:29:23 PDT 2002


William, Interesting thread... The first shipment of SB1800's are
scheduled to arrive in the US July 15th, a second larger shipment will
arrive 4 weeks later.

Regards,

____________________________________________
Kent Sheldon
Manager, Industrial Power Systems
SMA America
ksheldon at sma-america.com
925 513 8813 Brentwood Office (Primary)
530 273 4848 Grass Valley Office




-----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
>

__________________________________________________________________
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Miller Power and Communications
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email: wrmiller at slonet.org
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