Xantrex GTI dropout

cardinalflyer · July 2010

Hello,
My system consists of 72 BP SX170 panels, 2 Xantrex SW5548's and 2 Xantrex GTI's. I have my system grid tied to sell back to the grid.
Over the past 3 years, I have had to replace 3 GTI's because of intermittant dropout from grid tie. This dropout causes the inverter to stop selling to the grid. After much testing of the grid AC, Southern California Edison doing a 3 week long test of the grid feeding my system, a new power transformer on the pole feeding AC to the house to insure the AC was clean and not causing the inverter to drop out, I have traced this failure down to something that I wouldn't have though would have been the problem.
The inductor in the Xantrex GTI either shorts to the iron core or opens up when it gets hot having a lot of AC current passing thru it while the inverter is in sell mode. Xantrex Customer Service was totally un-helpful. I was told that Schnieder Electric/ Xantrex no longer supports the SW or GTI's any longer. I was told to just disconnect the GTI. I did this and found that my system is down by 20 percent selling back to the grid on this one GTI failed inverter combination. Typically each leg of the AC being sold is around 32 KWH per day. On the failed GTI leg, I am lucky if I get 24 KWH a day. Without the GTI my system is illegal in California without it in line. Given the thousands of dollars invested in this system, this is unacceptable.
Xantrex offered to sell me an XW series system to replace the SW system I have at a discounted price to replace the entire SW system. I only had to come up with about 9 grand to do the job.
Big DEAL! I haven't finished paying for the system I already own. My system is only 5 years old and I have a bloody fortune tied up in it.
I appologize for writing a book before I ask my questions.
One, does anyone know what the specs are on the inductor in the Xantrex GTI so that I could replace the inductor?
Two, does anyone know what can replace an SW5548, 48 volt system for battery backup, other than the XW6048 if the GTI's are in fact nothing but a pile of junk?
I have given up on Xantrex products. If they will only support products for the life of its production, then the solar industry is in trouble.
Lack of factory service on products that cost thousands of dollars only after a few years of service is deplorable.

Thanks in advance for any advise you may have.

autoxsteve · July 2010

Re: Xantrex GTI dropout

wow. 2 year warranty only on those. bad jobu there.

I bet Solar Guppy could help. Did you have someone install the system for you? Have you spoken to them about it (are they standing behind the installation/products?)?

Good luck I am sure you'll be able to repair it. Have you opened up one of these to see ifyou can sleeve the inductor?

cardinalflyer · July 2010

Re: Xantrex GTI dropout

Thanks very much for the reply...
Yes I have contacted my installer. He says he wished he could honor the factory warranty. Unfortunately the warranty expired along with the support from Xantrex. He did say he would charge me nothing to replace the inverter system, if that is what I have to do and rewire it as required except for materials used. He did replace all 72 of my BP panels at no charge after we found so many of them failing to work over time. It was discovered BP had a design/ manufacturing flaw in the production of the lot of panels that mine were shipped from. BP hired several consultants to evaluate the panels at great expense to them. The consultants said there was indeed out of spec failures on 16 of the 72 panels. BP chose to replace them all. BP paid the installer and shipping both ways. BP also gave me a new warranty on all 72 panels starting from the day the replacements were installed. Their warranty is 25 years...

AntronX · July 2010

Re: Xantrex GTI dropout

cardinalflyer wrote: »

...It was discovered BP had a design/ manufacturing flaw in the production of the lot of panels that mine were shipped from...

Can you tell how exactly those panels failed? Also, 2 year warranty on inverter is just silly. Inverters should be designed to last 20 - 25 years.

cardinalflyer · July 2010

Re: Xantrex GTI dropout

What was found on the BP panels that failed was:
Poor solder joints between cells.
Poor solder joints on terminals from the top of the panel to the output terminals.
Poor sealing of panel glass.
A few had bad bypass diodes.
From what I have been told, most of the failures were caused by workmanship issues in the panel manufacturing plant in Spain which has since closed. All BP panels are now working 100 percent. I check the output of each set (36 pairs of two for 48 volt output) with a Fluke 337 clamp on DC current meter every few days at the DC breaker panels, while they are operating normally.
As for the warranty from Xantrex lasting only two years and should last 20... Does fat chance mean anything to you? These days most Xantrex Solar products are warranted for 5 years, but one can buy an extended warranty for another 5 years if one so desires. At the time I purchased my system (2005), Xantrex only had two year warranties with nothing beyond that period of time available.
The only question is, even with a 10 year warranty will Xantrex be around to honor it or will Xantrex build a "new and improved" inverter and abandon the inverter that one purchased with a 10 year warranty?
So far in the past two years, Xantrex has been sold, has developed and are selling "new and improved" XW series inverters and the SW series is kaput. Not a very good record in my book.

RCinFLA · July 2010

Re: Xantrex GTI dropout

If it wasn't for bad luck, you would have no luck at all...

The SW GTI was always a poor 'bandaid' to issue of raw SW did not meet the new UL1741 regulations.

I am surprised it lets you sell without GTI. The older units, prior to Dec 2001, software allowed selling without GTI. This was prior to the UL1741 and the GTI.

Software rev 4.2 and later has GTI rigging.

I was under the impression that the newer revision of software would shutdown selling in a few seconds if there was no GTI attached.

Just a guess but you might have a grid phasing issue with choke in only one leg of a series stacked arrangement. The stacking interface sync's the two at 180 deg phase for the 240v, but the ACin, with only one series choke, is going to shift L-N phase on one side.

The series stacking cable may only sync the two at 180 degs when there is no ACin.

RCinFLA · July 2010

Re: Xantrex GTI dropout

From what limited documention I have downloaded, it looks like the choke is used to allow the SW to raise and lower the inverter voltage compared to grid with the choke providing a voltage dropping inductor (ballast). The delta is probably only about 15 volts. There is an AC voltage measurement on the grid side of inductor in the GTI, that is sent to SW unit. The SW already has AC1 AC voltage measurement on other side of inductor (along with AC1 current measurement).

If grid is present and not islanding, the grid side of inductor will stay fixed due to the low impedance of a valid grid.

My guess is the inductor is about 1.5 mH, capable of passing 30 amps without saturating. There is a bypass relay in GTI that shorts inductor out when not in selling mode.

You can always take the other good one and measure it.

Another item you might want to check is the small voltage sense transformer on the PCB. If it is the same one used in the SW unit they have a nasty habit of getting creamed by lightning strikes on the power grid. If it is the same as one used in SW unit it is a 120vac primary to 13.8vac secondary, that is actually measured by ADC converter.

cardinalflyer · July 2010

Re: Xantrex GTI dropout

Thanks RCinFLA for the information. I appreciate it very much.
My SW5548 works without the GTI, by disconnecting the data cable from the inverter to the GTI. That is all I did. I have sent 3 emails to Xantrex and called them twice about this GTI situation and haven't received on reply from them, nor have I recieved any information on how to "legalize" my system without the GTI by calling them on the phone. All they have told me was to buy the XW inverter and that would solve my problems.
May I ask, where did you find the info on the GTI? I have spent hours trying to find some technical info on this piece of junk and have had no luck.
I will check the voltage sense transformer to see if it is in fact putting out 13.8 volts. If the transformer has failed, do you know if they are availble? I found the shorting and transfer relays at Newark Electronics. The small switching relays are a little harder to find with the correct pin-outs, but I am working on finding them to. As for the inductor, you were pretty close on the value. I measured 1.4mh. The trick now is to find one of that value and current capablity that will physically fit in the box.
My dealer/ installer advised me that he is ripping out several Xantrex installations and replacing the inverters and GTI's for several customers he has and would be more than happy to dump the GTI's off in my driveway. What a guy!!
He told me they all have failed exactly like mine have. This problem has not only been a lot of grief for me but from what he told me, its been a nightmare financially for him supporting these products.
I am determinded to get these things fixed. I should have known these GTI's were as you call it "a bandaid" to make them comply with the standard when I bought them. Little did I know that Xantrex was going to dump them as soon as they did. In the business I'm in, we have a saying.. You're only good as your last show! Thanks again RCinFlA for you help. I appreciate it very much.

RCinFLA · July 2010

Re: Xantrex GTI dropout

I don't have a GTI but have four SW units.

From what I have read, the GTI primary component of operation is the series choke.

One of the problems with the SW and UL1741 is making the grid presence testing, required to detect an open grid, but perhaps driving the neighbors house. (islanding). The SW have three transformers (Papa bear, Moma bear, and baby bear). These three transformer secondaries are wired in series. This only allow a maximum of 27 different voltage steps available to make a sinewave, typically, depending on battery voltage and AC grid voltage, less then 27 steps are used.

This means the inverter output voltage adjustments are rather coarse, roughly in about 9vac to 15 vac increments. The newer XW inverter with high freq PWM incremental control has almost infinitely fine resolution on making output voltage adjustments.

The series inductor acts like a ballast to allows the SW to raise and lower the inverter voltage without causing such large current surges in and out of the inverter that also back up into the batteries. The inverter instantaneous voltage delta relative to grid may result of inverter shifting the sync'd phasing relative to grid phase.

When power grid is good it is like the immovable object. Any attempt by inverter to raise or lower the matching voltage or frequency phase will be met with stiff opposition. So as the inverter voltage is raised, the inductor allows the inverter to move up some, but on the grid side of the inductor it will not budge in voltage.

The GTI inverter measures this grid side voltage and reports it back to SW through GTI interface. Besides this voltage reading there is some control lines to engage the power relay that shorts out the inductor when it is not needed.

What I don't know is whether the series inductor is left engaged the whole time during selling or whether it is only engaged every so many seconds when grid presents testing is performed during selling. If the latter, then the power relay is clunking all the time when selling and really would take a beating.

I think, without the series inductor the surge current will be whatever the max ACin current and max AC charge current setting are. They might even be higher.

The info I got from Xantrex site, I think. Attached are a couple.

t00ls · July 2010

Re: Xantrex GTI dropout

when I put my first system in, I had 2 sw 4048's with the interconnect cable to sync them up.

the electric company came out and did testing on the harmonics and how fast the inverters dropped off when there wasnt any voltage at grid.
what happened was that the inverters synced together kinda slowly shut down (1/2 a second) I think dont remember.....the gti is supposed to take care of that

what I read off the xantrex site was that you could use capacitors to correct the power factor....I think it would also take care of the harmonics and the dropout

here is a link to that document http://www.xantrex.com/web/id/341/DocServe.aspx

heres the link to other tech documents http://www.xantrex.com/support/web/id/1001/support1.asp

hope this is helpful

cardinalflyer · July 2010

Re: Xantrex GTI dropout

Thanks Tools,
I haven't looked at the capacitor approach yet. I will read the article and see what I can figure out. Did you use capacitors in your system? If so, what did they do for you?
A note to all the readers out there. Thank you all for the help and suggestions you have offered.

Xantrex GTI dropout

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