I just started this tread so if you have opinions or want to just express yourself there would be a place to do it !!

Just keep it clean

Thanks

Is there hope for the Xantrex ST & STXR series? I purchased a ST2500 about a year ago, knowing that there were problems with the firmware. Since firmware can be upgraded, I ***umed that there would be future releases that would correct the problems. After all, how difficult a technical problem is it to design a MPPT algorithm for an inverter? As we know now, it is impossible for the current engineers at Xantrex. Their solution to the ST problem with the status display showing bizarre behavior (MPPT thrashing) has been to dumb down the display on the STXR and not show the disturbing numbers.

How long should I hang on to the hope that Xantrex will fix the ST/STXR? Have they already written me off by declaring my ST an obsolete version that is no longer getting development? Even though the STXR behaves even worse?

I like the specifications of the ST/STXR. Using 6 strings of 4 panels each is a good design. The 48 volt nominal design seems inherently safer than the SunnyBoy's requirement to string everything together for an operating voltage of up to 600 volts. And I suspect that the SunnyBoy is much more sensitive to unnecessary shutdowns due to grid impedance anomalies. The ST/STXR has a built in fan, while SMA is considering how to add a fan. While I prefer silence, if a fan is necessary, then it should be included. The basic designs seem to favor the ST/STXR functioning more of the time, at safer voltages, and at lower temperatures. The reality is quite the reverse - the SunnyBoy reliably delivers about 25% more power than the ST/STXR.
[img]images/smiles/icon_mad.gif[/img]

I have a pair of ST-2500s running from identical 16 module KC-120 pannels and the units also exibit the same startup problems. The West unit start a good hour after the East one, and produces about 10% less each day. While in its early morning thinking mode, it cycles the fan on for 30 seconds then off for 20 seconds and does this for an hour. Finnaly it starts and produces at approximately the same level as its East twin. Complaints to Xantrex get a technican who listens politely, but offers no solutions. The West unit also exibited another unusual characteristic this summer in that it would produce a high pitch squeal for 20 seconds out of every minute, going for hours at a time. The unit is in the shade on 100+ F days. Same technical advised that when it quit producing, I should let them know and if it was still under warranty, they would fix it. It's still running,so I guess the neighbors will just have to suffer. Squeal goes away when the days get cooler. [img]images/smiles/icon_confused.gif[/img] null[email]null[/email]

I have started to respond to this post a few times since I first saw it yesterday. I didn't like the way my response was rolling up (primarily because I felt like a flameboy with both barrels blasting and I don't want to come off that way). [img]images/smiles/icon_rolleyes.gif[/img]

A little background:

I came close to getting a Xantrex inverter before I started hearing about problems with their product. Then I saw the SMA/Xantrex comparison article in Home Power, which confirmed what I had heard.

Frankly, I would be furious if my experience with these inverters was the same as you describe.

I realized that maybe we all need to know what Xantrex is really willing to do about your problem (if anything) and how clear it is to them that you really have a problem. I also realize that some "hard core" evidence for Xantrex that you have a sick inverter might be in order.

Problems &/or issues (by order listed in your post):

1> West inverter cycles the cooling fan on & off before it even starts producing.
2> West inverter starts producing an hour after east (this is an issue only if both systems really are "twins" as you state).
3> High pitched squeal from West inverter.
4> Neighbors ("just have to suffer") impacted by your installation.
5> Having to wait for west inverter to fail completely and "if it was still under warranty, they would fix it".

Thoughts about these issues:

Item 1: Does Xantrex have an explanation for the West fan cycling on and off before it starts producing? Why doesn't East do the same?

Item 2: Does Xantrex have an explanation for the difference in starting times (again, only if these systems are truly "twins")?

Item 3: Does Xantrex have any explanation for the high pitched squeal? And again, why only West and not East?

Item 4: Neither you nor your neighbors should have to endure a high pitched squeal from your inverters (note that some noise is understandable while in close proximity to the units, although you would expect the noise would be closer to 60hz hum than a high pitched squeal). The relatively young Solar Industry does not need this kind of "ill will" over how the technology impacts people, and I sincerely hope your neighbor isn't the type to write letters to the editor of your local newspaper... As an aside, I'd bet $5.00 that any AM radio in proximity to this inverter while it is squealing is also useless.

Item 5: This is probably my biggest "hot button". You have described what I consider a defective unit that will fail completely at some point, and it is still under warranty. If it totally shuts down after the warranty expires, you get to foot the bill for the defect!

Thoughts on Next Steps:

Have you tried swapping the East inverter for the West Inverter? With all other conditions remaing the same, if the problems move East with the interver, I'd say you have a very clear cut case.

Did you install the system yourself or was a contractor involved? If a contractor, have you pointed this problem out to him/her? I would press the contractor to get a unit swapped out ASAP. If you still get no satisfaction, then you should consider talking to the contractor state license board (I see you are in CA - www.cslb.ca.gov) about the problem. It would probably be a good idea to tell them up front you think this is problem with a product sold by your contractor and not the quality of his/her work.

If you "rolled your own", have you talked to the organization you bought the unit from? I suspect you can get some help with one or more organizations that talk to consumers of products, such as CA Dept of consumer affairs (www.dca.ca.gov), AHAM - the A_sociation of Home Appliance Manufacturers (www.aham.org) &/or The Bureau of Electronic and Appliance Repair (www.bear.ca.gov)

Also, since these units are grid tied and they are UL approved, you could consider contacting the California Public Utilities Commission (www.cpuc.ca.gov) &/or Underwriters Laboratories (www.ul.com) about these issues.

Death to Xantrex?

OK, by now you might think I hate Xantrex - this is simply not true. Actually, I think that if I were Senior Management @ Xantrex, I would be pressing my engineering department bigtime to get problems like this nailed and satisfy my customers ASAP.

Note: I don't know if this is a problem that the engineers should "own" alone either, frequently Management is the larger part of a problem with product issues, especially where delivery timeframe incentive bonuses &/or marketing pressures cause product to release before it is ready.

I think that competition is king. SMA appears to have this Xantrex line running for their life (whether they know it or not). I think it would be great for Xantrex to save their [backside] by releasing an inverter that "raises the bar" in all ways relative to SMA (note applicable areas such as overall efficiency, customer satisfaction, reliability, etc).

Xantrex better hurry though, their reputation already looks tarnished... remember that one "Oh sh_t" can wipe out a hundred "Attaboys".)

(Administrivia: Be Safe / Only my opinion / Other viewpoints=invited+encouraged)

(c) 2002 Roger@vipmail.com

Followup info: To be fair, I noted that there is an update notice (released Oct 1, 2002) on the Xantrex website that refers to "under certain conditions, some customers have seen performance that falls below what we would consider industry-leading".

The article claims that the upgrade is expected by the end of December. I don't see that all the issues discussed would fall into this upgrade, but the problem(s) they are fixing are not clearly described so perhaps Xantrex can speak to this?

-Roger

Hi Rob, Alan and Roger,

Thanks for noticing the post on www.xantrex.com for the upgrade program. There are significant financial investments being made to "step up to the plate" and meet the performance of other competitive products. The issues being addressed are: MPPT energy harvest efficiency including cloud tracking, fan operation, noise, display issues, units arriving DOA, wakeup routines, sheet metal inconsistencies, and more. This work is currently in very capable hands and Xantrex is pouring the in the resources to support these efforts. Please know that Xantrex is standing 100% behind its equipment and you, the customers.

Thank you. Tobin Booth, Xantrex Technology

Tobin, Thanks for the reply. I will certainly be looking forward to the revised firmware. The West unit is 10 ft lower than the East unit and gets shaded by East at sunrise. There is a middle tracking array with 8 pannels and it gets no shade from East. Four of the mid panels are attached to the West inverter and as the sun rises, sets of four pannels on West are taken out of the shade sequentially. The fan routine normally starts after all West pannels are exposed to full sun. Until then the LCD just shows 247VAC and 83VDC, 0000 Watts. I also have noticed problems with the moving clouds as noted by the recall notice. Of course, from where I live in the desert, clouds are a rare sight. This summer that was different, with lots of clouds. I also had the same problems noted, elsewhere in this forum, with the mechanical layout...but the nice aluminum case and a hole punch solved that one quickly. I'll be glad to work with your company on this issue and it should be noted that even with these blimishes, the inverters are producing an average of about 600kWh each month.

It is good to hear that top Xantrex management has finally decided that their performance to date has been unacceptable. Customers have only been saying this for several years. Without SMA demonstrating the poor performance of the ST2500, they would still be dismissing our complaints as uninformed dreamers.

The announcement specifies poor cloudy weather performance as the problem they are working on. Even more basic is poor performance during stable conditions. I can be watching a bright cloudless sky, as the ST2500 thrashes up and down between producing 800 watts and 1600 watts. Earlier firmware caused it to thrash between zero and 1600, so they have improved from the first attempts. The next problem is that the maximum performance seems to be throttled back. I can be making 800 watts at 2 amps per string (times 6), and when the amps go up to 5 as the sun goes higher, the watts go to 1400. I understand that watts equals amps times voltage, and my complaint is that the MPPT algorithm is doing a poor job of controlling the voltage.

The best MPPT implementation currently appears to be the OK4 (locally known as the Trace Microsine) inverter. An interesting performance test would be a side by side comparison of power output per panel with an OK4 inverter versus the SMA & Xantrex units. The OK5 looks even more interesting, since it can support a 48 volt string like the ST2500 uses. You could even take one string off the ST2500 and move it to an OK5. The biggest problem with the OK4/Microsine is the price per watt, and the OK5 appears to be a major improvement in that department. Lots of small MPPT inverters instead of one large inverter is attractive where the panels are subject to different orientation and/or shading. It will be a while before the OK5 is available in the US, but it will be a welcome addition to our current choices.

Where can one look at the spec's on these inverters ??

The microsine hasn't been made in years I thought ... and was it ever UL1741 approved ?

The OK4/OK5 are made by a Dutch firm named NKF Electronics. Check out www.nkf.nl/electronics/photovoltaics

The MicroSine is just an OK4 marketed by Trace. Trace dropped them, but the OK4 continues to be available. The OK5 will be priced at about $1.10/watt, with a target of $0.50/watt when production is fully ramped up. I'd buy 2400 watts of inverter for $1200! They've got their work cut out for them in establishing their European market, so I wouldn't expect them to market directly here for some time. On the other hand, the OK5 comes in 120 & 240 volt versions, both of which autoswitch between 50 & 60 cycle power.

The MicroSine does have UL 1741 approval. Care to bet how many installations have power company approval? My guess is zero, considering the ease of just skipping that step. The OK5 is probably designed to meet UL 1741, but until someone in the US jumps through the hoops we're probably talking guerrilla installations here.

There is another company named MasterVolt that makes a device similar to the MicroSine. As far as I can tell though, it is only available in a 240 volt / 50 cycle version. It is basically a wall wart (plug in transformer) that inverts power from 1 or 2 solar panels.

[ October 05, 2002: Message edited by: Rob Larson ]

NO way this is UL1741 approved ... it claims "Field adjustable voltage and frequency limits " which I am 100% certain UL doesn't allow

You can get a used suntie for 50 cent/watt (Ebay) which can then be upgraded for free. You will end up with a warrented , UL1741 inverter for your 50 cents a watt target ...

Quote from the MicroSine Owner's Manual on the TraceEngineering website:

"This product is manufactured by NKF Kabel for Trace Engineering. The MicroSineâ„¢ inverter is UL listed to the UL Standard 1741 (Draft), Static Inverters and Charge Controllers for use in Photovoltaic Power Systems. It is listed for use either separately from the photovoltaic modules or as a listed component for factory ***embly into an AC photovoltaic module / inverter system. Consult local authorities as to national and/or local electric codes and any additional installation requirements."

I don't know if it should have been listed, but Trace documentation claims that it is. There may be differences between the OK4 and the MicroSine that are required for regulatory approval in the US. It wouldn't surprise me if the current OK4 distribution is using the Trace UL listing, which may no longer be valid.

Regardless of the current regulatory situation, the MicroSine/OK4 is a very effective device. It's primary problem is the cost per watt, which clearly limits it's market potential. The OK5 corrects this problem and should be competitive in the current grid-tie inverter market. The claimed potential is that they can cut the retail price in half, while maintaining a 20 year design life.

It's great to hear that you are optimistic about the upgraded ST. I look forward to your performance report on it.

Rob,

I dug thru the manufactures web site and if you dig deep enough you will find almost ALL of the production is used in the Netherlands

Only for the year 1998 were any units offered for sale to the US , which makes sense since that would have been the draft of UL1741.

This unit is not UL1741 approved and is NOT for use in the US. I will work with Xantrex to see what can been done about this since this is clearly not something that people should be using. The website that one can buy from is not allowing returns so folks ... DONT BUY THESE DEVICES.

On the OK5 , this will never fly in the US , they are using peircing of the AC lines for connecting the inverters , this won't meet NEC requirements and you can't have unprotected 120 VAC running on the backside of the panels , this would require conduit.

This outfit is making inverters for there country and thats fine but don't be lulled into thinking it will be here or legal in the US.

Sorry If I'm comming across as a hard-*** on this one but folks , saftey is a real issue and it not just your *** that's on the line , it's our industry as well.

Thank you for your comments and this is what I had hoped solar-guppy could do , have real questions about real products and get real answers

The history of the MicroSine is that Trace sold it, and claimed UL 1741 certification. I tend to believe that they legally offered it for sale, and that all units sold were (and are) legal to use according to the UL 1741 requirements at the time of initial sale. From what you say, NEC compliance would require (at the minimum) addition of a DC disconnect.

As long as we're quoting rules & regs, I'm rather upset that the ST2500 was placed on the certified equipment list for the California BuyDown program. Xantrex claimed, and some bureaucrat agreed that the ST2500 provides 93% efficiency. You've demonstrated that the 93% is advertising copy, not measurable performance. That 93% figure is used in calculating the amount of money the state rebates for the inverter, so it seems to me that it a legally important number. Who is watching the store?


Shifting gears...

There are currently three general designs for grid-tie inverters. The ST uses multiple strings of groups of 4 solar modules for a 48 volt nominal system. The SunnyBoy uses fewer strings for a up to 600 volt system. The OK5 is a small inverter that supports a maximum of 4 panels.

These design differences impact the final performance of an otherwise identical system. The SunnyBoy design would seem to be potentially the most efficient, since there is no need for a conversion step between 48 (actually more like 65) volts up to whatever is required (300?) to supply the grid at 240 volts. While it is more efficient than the ST design, it is also more dangerous and less fault tolerant. The OK4/OK5 design is attractive because it can be scaled in much smaller increments. If you have multiple orientations (a mixture of south, east & west facing panels), the OK4/OK5 design allows MPPT optimization at each orientation. A single large inverter simply cannot optimize a multiple orientation setup - it is going to be a compromise.

The regulatory problems of the OK5 represent minor design adaptations compared to the technical problem Xantrex has had with design of a decent MPPT implementation. From what I can tell, the OK5 needs a different mechanical connection to the house wiring. AC and DC disconnects are needed. I didn't notice if they have ground fault equipment. And the anti-islanding adjustments may need to be restricted to meet UL 1741. They clearly have the US as a target market, otherwise why include support for 120 volt 60 cycle power?

Xantrex got blind sided by ignoring SMA as a potential competitor. They should have collected competitive performance data on the SMA line long before they finalized the ST design. The OK5 represents another significant design that could cause them real trouble if it got proper localization and marketing. The OK5 offers a superior solution for installations with either just a few panels, or with panels at a variety of orientations.

Xantrex provides a 2 year warrantee for the ST/STXR, with an optional upgrade to 5 years. SMA provides a 5 year warrantee. NKF is talking about an expected 20 year life for the OK5 design. Outback is really proud of the durability of their design. After the MPPT fiasco is past, the next competitive issue will be durability, and the ST isn't exactly a leader in that department either.

I'll know more about the OK4 in a few days , I've ask both Xantrex and SMA to look into this inverter and whether it is legal in the US.

I agree , publishing spec's that are vaporware is not a business like thing [img]images/smiles/icon_eek.gif[/img] and I am working with Xantrex to get things in order and will remind them to get the website spec's corrected

As Far as I'm concerned , the OK5 is just a paper product , it hasn't been field proven and anyone can make claims about how great there latest widget is but without one to test that meets , UL1741 , NEC ,building inspector's requirements and has been independently verified it doesn't mean a thing.

Don't so easily dismiss the cost in both time and money to met US regulations , the costs can run into the 100's of thousands of dollars and if your only going to sell 2000 inverters it doesn't make economic sense.

This year , I am told the entire US market is less than 6,000 inverters ... the only reason SMA got the R&D dollars is due too it was design for the German market and sold 40,000 units. Also The German Market has tougher regulations than the US which makes meeting our regulations a no-brainer. If you notice the OK4 (and OK5) are not sold in Germany.

The ST/XR mess is not directly of Xantrex's making and we can as owners can thank our lucky stars Xantrex is going to make wrong , right.

If this was still trace , they would just look the other way as they did thru 2 years of testing that showed nothing but problems. I've seen the actual test data FSEC and Lakeland Electric pilot programs provided to trace, They told Trace there were serious problems. No one that had anything to do with the ST is working at Xantrex now ....

Xantrex will end up spending millions , on problems that really was the fault of Trace Engineering which Xantrex got thru the acquisition a year and a half ago.

As for voltages you need about 380VDC to make 264 VAC in an inverter , 264 is RMS , not peak , hence when 380 is needed.

There are actually more than 3 choices now that SMA has 3 different models out , the smaller one (I think it is 700 watts) and will work with 4 panels I believe.

They are the same design as the SB2500 , they just use different transformers. Since the power board is the same H-bridge design , they run at the same current , but since the voltage is lower you get the lower power limit.

In two months folks will start being very very happy with there XR performance ...

I am under NDA with Xantrex [img]images/smiles/icon_wink.gif[/img] ....

[img]images/smiles/icon_smile.gif[/img]

[ October 07, 2002: Message edited by: Solar Guppy ]