[RE-wrenches] trouble shooting system with Sun Tie

[Dana Brandt]

Thanks for your feedback everyone. I called Xantrex tech support. They
weren't interested in helping me determine what the problem was and
just assumed it was a faulty inverter. I've been really disappointed
with Xantrex tech support the last few times I've called. I no longer
get someone on this continent who knows about the inverters, which is
frustrating.

They no longer have a swap program and offered me a GT2.8 for $999.
Even with all three strings in series, I still think the voltage will
be on the low end for that inverter so I'll probably go with a Fronius
IG2000.

Dana

-- 
Dana Brandt
Ecotech Energy Systems, LLC
www.ecotechenergy.com
dana at ecotechenergy.com
360.510.0433


On Thu, Sep 11, 2008 at 9:04 PM, Allan Sindelar
<allan at positiveenergysolar.com> wrote:
> Randy and Dana,
> Not sure here (never installed a SunTie, thanks to this list in the early
> days), but I believe that Xantrex' swap program ended years ago.
>
> I see from your website that you're in Bellingham, Washington. OK, that
> explains your low expectations (1,123 kwh/yr from 1.44kW? Here in NewMex we
> estimate around double that).
>
> I copied some earlier (2001) saved Wrenches postings about the SunTie (then
> deleted them). I hope you find them enjoyable and enlightening.
>
> Allan at Positive Energy
>
>
> -----Original Message-----
>
> Dana,
> I thought Xantrex recalled all the ST1500s and replaced them with XR2500s.
>  Mine was, years ago.  You might check with them about this.
> Good luck,
>
> Randy Brooks
>
> Brooks Solar, Inc.
>
> Solar Power for People
>
> 140 Columbia View
>
> Chelan, WA  98816
>
> 509-682-9646
>
> Randy at BrooksSolar.com
>
> www.BrooksSolar.com
>
> On Sep 11, 2008, at 3:23 PM, Dana Brandt wrote:
>
> Hi all,
> I was called out this week to trouble shoot a system I didn't install.
> It's a five year old 1.44kW system with the following: Sun Tie ST 1500
> inverter and 12 Astro Power modules. It only produced 634kWh last
> year. With our sun here, the shading, orientation, equipment, etc. it
> should have produced around 1123kWh.
> I've heard a lot about Sun Tie failures, but don't know the details.
> What are the common failure modes? Is it likely that a failure of the
> Sun Tie would leave it operating, but only producing half what it
> should?
> When I showed up the system was producing 950W on a relatively sunny
> day - seemed pretty reasonable. After restarting the inverter it only
> produced around 150W. Is the MPPT very, very slow to find that sweet
> spot, or what was going on there?
> The system is comprised of three strings of 4 modules each. When I was
> there all three strings were producing about the same current, so that
> leads me to believe it's not a module failure.
> To make things more fun, the modules were installed at two different
> orientations. One string is at 38d slope, 30d east of true south,
> while the other two are at 36d slope, 75k east of true south. This
> certainly has a detrimental impact on the performance, but it doesn't
> seem to me that it could account for all of that energy loss.
> Thoughts?
> Thanks a lot!
> Dana
> --
> Dana Brandt
> Ecotech Energy Systems, LLC
>
>
>
>
>
> [5/19/01]
> "Brand X" has been taking a lot of arrows lately, some in jest and some
> deserved. I can't believe that Xantrex is trying to help Advanced Energy
> Systems and SMA gain market share, but it sure looks that way. A little
> history and an important question.
> First, the ST2500 becomes the hottest thing in PV since the SW.
> Next, ST2500 demand exceeds production.
> Next, ST2500 has software problems.
> Next, Xantrex is "experiencing a shortage of vendor supplied parts" and
> shipments stop.
> Next, Xantrex tries to get us to switch to the derated ST2000-CB.
> Then, Xantrex announces the XR2500 at $2759 with nearly the same specs as
> the $2500 ST2500.
> Meanwhile, we are told ST2500 inverters are still being produced and to
> continue to take customer orders.
> However, I am waiting for ST2500 inverters that I ordered since April 4.
> (How long are you back-ordered without ship dates?)
> And now we are told that the XR2500 "will be available for delivery by July
> 1."
> Joel Davidson
>
>  > [2/14/01]:
>>The ST normally tracks the solar irradiance fairly accurately, when a cloud
>>passes over the output drops proportionally. The LCD meter is powered
>> solely
>>from the array output, no AC backup power. The ST will disconnect from the
>>grid if the grid voltage goes out of the window of acceptance. UL 1741
>>requires a 5 minute timeout before reconnecting.
>>The cooling fan comes on at about 200 watts of output; it is controlled by
>>output, not thermally controlled. (This may change with future versions of
>>the ST.)
>>
>>Here is the situation with the dealer's system. There are two 2300-watt
>>arrays with an ST2500 for each array. To date, the ST as generated up about
>>1,800 watts of output from each array. The LCD indicates that the ST
>>intermittently cycles OFF-ON at around 600-700 watt output level. The unit
>>does come back on. It appears that the LCD can, under some circumstances,
>>"lock-up". During the lock-up the LCD only displays "Rev 3". So far Trace
>>has not been able to recreate this "lock-up" even with a unit that suffered
>>from intermittent lock-up in the field. Trace is still studying the
>> problem.
>>Perhaps there are some sensitivities to installation environments, like
>>inductive coupling to a parallel high voltage line at the site.
>>
>> >From conversations with the Trace engineers, the occasional, intermittent
>>cycling seems to be caused by the ST's MPPT algorithm being a little too
>>aggressive in tracking the mpp on the knee of the IV curve. It appears that
>>with certain modules, under certain conditions, the algorithm can
>> over-shoot
>>the knee of the curve. Trace is actively studying any occurrences of this
>>problem. If and when a new algorithm is released, it will be field
>>upgradable with a single replaceable chip.
>>
>>The Trace engineers have been very helpful and responsive with this
>>situation. They are very willing to help with any problem ST installations.
>>They both want help get the system running and they are learning about
>>unexpected glitches and quirks that can occur with any new product release.
>>
>>Several dealers have asked my opinion about the ST inverters. I advise them
>>the ST (Rev.1) like any other first release product, is very likely to have
>>some quirks and problems that occasionally show up. If I were to
>>sell/install any newly released, Rev.1 product, I would advise the customer
>>that "the product is a first generation product and there may be some
>>unexpected quirks. That both I (the dealer) and the factory will stand
>>behind the product and will work to resolve any problems that might occur."
>>If the customer (or you as the dealer) are not comfortable with that
>>arrangement and understanding, then they should either choose another
>>produce or wait until the new product has proven itself in the field
>>(perhaps with a few up-grades or expanded installation guidelines).
>>
>>I hope this helps shed some light on the current situation with the ST
>>inverters. If any of you dealers are having problems with STs that you've
>>installed and your distributor can not help to work with Trace, please
>>contact me and I will see what I can do to help.
>>
>>Sincerely,
>>Steve Bell
>>SunWize Technologies
>
> [2/9/01]
> According to well-informed sources, there is pressure being put on Trace to
> pull them from the market until they work out the bugs on the MPPTracking.
> I don't know about you all, but reading reports of a 2200 watt system under
> full sun putting out all of 800 or so watts is rather disturbing.  With the
> grid-tie market going crazy in CA., it would give the industry and real
> black eye if battery-less ST systems were putting out a fraction of the
> appropriate output.
> Marco Mangelsdorf
>
> [2/7/01]
> I just got off the phone with John, our dealer (he is competent) ; here
> is what he says.
> He has two ST-based systems operating; one is a single ST2500 with 1,000
> watts of Arco modules, the other is system has two ST-2500s and about 2,200
> watts of UniSolar modules per ST.
> Both systems seem to be acting the same way. Multiple times during the day
> the ST will power up to about 650 to 700 watts and then cycle off. Many
> times the LCD display goes dim or shuts off and the Total Daily Watt-Hour
> reading on the LCD re-zeros when it cycles down. The units do come back on
> after a short while. This happens many times during the day.
> Although he does not have exact monitored data, it seemed that the power
> output of the ST is well below expected. On a sunny day with 2,200 watts of
> UniSolar the ST was indicating less than 800 watt-hours of output.
> The cooling fan comes on whenever the ST output climbs above about 200
> watts.
> John talked to Dean at Trace about the problems he is having. Dean says that
> the ST may cycle off and on several times in the morning and then
> occasionally (two-three times) during the day. John reports that the cycling
> is much more frequent throughout the day.
> Dean says that the ST may be too aggressive in its power tracking and they
> (Trace) may need to adjust it's aggressiveness. The fan operating anytime
> the ST output is over 200 watts is supposed to be some code or regulatory
> requirement. (It seems like it should only operate when the ST is warm.)
> Because the ST sometimes losses the daily watt-hour total on the LCD when it
> cycles, it sounds like the unit is totally cycling down during it's many
> daily cyclings. (The LCD also shuts off and clears the WHr total every
> night.) It sounds like Trace may need to supply a replacement chip to fix
> this cycling problem. It also sounds like some independent measurements of
> ST output v.s. array input may be well advised.
> In fairness to Trace, this is their Ver.1 of the ST. Hopefully they will fix
> the problems quickly. Remember the Ver.1 SW-series had problems too.
> I hope this explaination makes sense. Thanks for all the feed-back so far.
> Any other experiences with the ST are welcome.
> Steve Bell
> SunWize Technologies
>
>
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