Xantrex System Failures

Re: Xantrex System Failures

UPDATE:

Various of my installers were out here yesterday and the day before unsuccessfully trying to get my Solar Power System working. I'm going to summarize here, but I'll probably miss a few things. If so I'll post more here, and I'll try to answer any questions. To remind everyone, my System is:
36 Solar Panels rated at 245W each (previously I had said 240W each, but I looked at the wrong document then) for 8.8 kW
3 XW-MPPT60-150 XW Charge Controllers
4 Xantrex XW6048 Inverters (rated at 6kW each)
2 XW Power Distribution Panels (PDP) serving 2 Inverters each.
XW Automatic Generator Start Module (w/ 8.5kW generator)
XW Control Panel
48 Trojan L16RE 2V batteries arranged into 2 banks of 24 each.

Unfortunately, the guys yesterday had not talked to the guy who came out the previous day so there was considerable repetition of failures. At least the guy on the first day updated the firmware in the Inverters; it took him 3 hours to do that. The mode I have called "Perpetual Motion" (one Inverter charging the batteries from the output of the other three Inverters running solely on batteries) occurred on both days. The bunch yesterday insisted this is normal despite me explaining the first 2 Laws of Thermodynamics to them several times. Finally, they called Xantrex, and the Xantrex Tech had them reconfigure the System to make the Inverter that was spuriously charging the batteries the new Master. The Tech claimed that the Inverters have variations in sensitivity to the battery voltage, and that Inverter had gotten confused and thought it was grid-tied--it was trying to charge the batteries from the grid. I'm not comfortable with this solution as it seems to be jury-rigged. I'm afraid that aging of the Inverters will cause another slave to think it is grid-tied and try to charge the batteries from the output of the other Inverters. I don't see how with proper wiring this could happen. The installers think this is a permanent fix; I'm afraid that it is only temporary.

The guys yesterday claimed that the System was working because they had fixed the System wiring (ironically, one of them was responsible for the original wiring). In any event, they attributed the failures the previous day with the other guy to the wiring. After fixing the Master/Slave problem described above to avoid the Perpetual Motion mode, I insisted on real load tests:
A. The 1st test with the Solar Panels cut-in (i.e. available): We got up to 18kW, and I noticed that the Solar Panels were supplying power. This was supposed to be a test of the batteries alone. They went on the roof and cut out the panels (the Charge Controllers switched to display insufficient light). With the Solar Panels unavailable, the System crashed with an F48 error (under voltage in the DC system). Something to note in this test: we only saw up to 5kW from the panels displayed on the Charge Controllers. Since we are near the Vernal Equinox, and just after Solar local noon on a cloudless day in Central Texas (30 degrees latitude, 2200 ft. altitude), I asked why our 8.8kW of Solar Panels never supplied over 5kW? They made some measurements at the combiner boxes on the roof and announced that they could see 7.1kW up there which is normal!!! They told me that our 8.8kW system of panels really will only produce 7.1kW max.
B. The 2nd test with batteries alone supplying power: We got up to about 16kW load when the F48 fault crashed the system. These people's bosses and a Professional Engineer in the field have told me that my battery banks should be able to supply 24kW for at least an hour or more. These failures on batteries-alone make me suspect that my battery bank is screwed. I have not been successful in getting these guys to actually look at the battery banks. I cannot even get them to measure the DC current coming out of the battery banks during the tests (my clamp-on multimeter is only AC -- I need to find a good DC clamp-on one)! Then one of these guys tried to convince me that my 24kW bank of XW Inverters is really only capable of delivering 20kW and that is 90A to the house. I was very, very tired and not inclined to discuss that.

BTW, I have made a video record of all of these tests starting back in November. I can review them to get pretty much exact information on what happened.

The installer guys are returning Friday to try to get the System working. I don't know what they plan to do. I am nervous as the bunch yesterday was intent on calling the System fully functional because it was operating fine at no-load. Only my instance on real-load tests showed the System to be faulty. Yet while I insisted on real load tests, I am concerned about the effect on my appliances. We have to turn on a lot of big draw items to get near 24kW (and we haven't gotten there yet--it shows you how rarely we expect to need all 4 Inverters). I do not know how gracefully, these Inverters crash.

QUESTIONS:
1. Should I only expect 7.1kW max. from my 36 Solar Panels (245W each) from which I had expected 8.8kW?
2. Can I expect this to be a final solution to my Perpetual Motion problem as the system ages and other inverters develop different sensitivities to battery voltage?
3. Even with all the batteries in the world can I only expect 20kW from my four XW6048 Inverters as one install guy claimed?
4. Should I be worried about the effect of these crashes on my appliances?

Re: Xantrex System Failures

Blackcherry04 wrote: »

The 245 W comes from a laboratory test that is very hard to duplicate in the field, you'll never get the same tilt, azimuth and intensity to see it on a constant basis. If your lucky you might see it a couple times a year and then you may not see it on many panels at once. I have 8.2 KW and 35, 235 W, It usually maxes out around 6800-6900 watts. I have gone over 7000 a few times.

I hate to tell you , these systems very rarely live up to the promises they make when they sell them to you.

Thanks! I was unaware of this, but it is good to get better information than I get from the glossy brochures.

However, I see that you are getting 84% (at 6900W, 85% at 7000W) from your panels at optimal while our installer guys are telling us that the best we can hope for is 80% of ours. Moreover, I still have not figured out how one of the installer guys can go on the roof and see 7.1kW at the panels while the Charge Controllers are reading <=5kW at the System; I don't know where that difference of >2kW is going. Perhaps, I just don't understand what the Charge Controllers are telling me.

In any event, I cannot just accept what my installer is telling me. They have given me too much conflicting information. Should my System ever stand up to a real load test without crashing, my wife and I will find and hire an independent expert to examine all our subsystems and the integrated system before accepting it.