[RE-wrenches] trouble shooting system with Sun Tie

jay peltz jay at asis.com
Mon Sep 15 12:56:35 PDT 2008


Hi Dana,

I've got a old GT that I'm using for a grid-tie micro hydro.

This unit takes 5 hours to track any changes to the turbine ( nozzle  
changes or startup), amazing.

In comparison, a SMA 2500 takes about 30 seconds.

jay

peltz power


On Sep 15, 2008, at 11:26 AM, Dana Brandt wrote:

> 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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