My Xantex System seems to have a peak output that is lower than I think it should be?

MJones
MJones Registered Users Posts: 5
Hello,
I am new to this forum so if I posted in the wron place I apologize. I have been wondering why my solar panels have a rated output of 5760 Watts and my peak output on a very sunny day is 2.82 KW. It used to be 3.36KW but when they updated the breakers last year it changed. My solar system is generating peak 2.82 KWs. I think this should be higher given what I have. I was wondering if there is a configuration setting I can’t seem to find that will set the peak higher? My system is:
2 rows of 12 240W PV modules (5760 W) TSM-PA05
Combiner box with 15a series string fuses, 4 strings per container box
PV disconnect/breaker Xantex 865-1075 60a 160V dc
Battery disconnect/breaker Xantex 865-1075 60a 160V dc
4 Rolls Series- 4000 model-S530ah 24Vdc battery bank
(2) Xantrez XW MPPT60 150 Solar Charge Controller
(1) Xantex XW4024 -120/240-60 Series Hybrid Inverter/Charger
Hialeah EZ read meter
Critical Load Panel
200a main load panel with 150a breaker
Xantrex XW Power Distribution Panel
XW System Control Panel (1 in house, 1 at Panels)

All the components say Schneider Electric on them.

Any help/suggestions on how to get the peak higher (if possible) is greatly appreciated

Merwyn Jones

Comments

  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    Re: My Xantex System seems to have a peak output that is lower than I think it should be

    Your Trina panels have a NOCT (Normal Operating Cell Temperature) value of 174 watts so 174 x 24= @4175 that you could expect at the panels. So how far are the panels from the controller?

    Where are you measuring production? after the charge controller? after the Inverter?

    At what stage is the charging cycle when you are measuring? You only get maximum production while in Bulk charging, once you reach absorption you production is likely to be tapering off.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: My Xantex System seems to have a peak output that is lower than I think it should be
    MJones wrote: »
    Hello,
    I am new to this forum so if I posted in the wron place I apologize. I have been wondering why my solar panels have a rated output of 5760 Watts and my peak output on a very sunny day is 2.82 KW. It used to be 3.36KW but when they updated the breakers last year it changed. My solar system is generating peak 2.82 KWs. I think this should be higher given what I have. I was wondering if there is a configuration setting I can’t seem to find that will set the peak higher? My system is:
    2 rows of 12 240W PV modules (5760 W) TSM-PA05
    ...
    ...
    Any help/suggestions on how to get the peak higher (if possible) is greatly appreciated

    Merwyn Jones
    OK.
    1. You should not expect the full nominal power output except on the occasional cold clear summer day with full sun. :)
    2. But you should be getting more than 1/2 the nominal power and certainly as much as your previous high of 3.36.
    (3. Is there any issue with shading of the panels? One which has grown since installation as a tree grew?)

    So, based on 1 and 2, something is wrong with one or more panels or with the way they are wired, or with the charge controller. Or, as Coot said, you just are not needing full power to keep the batteries in the Absorb or higher state.
    Simple, no?

    Since you have two strings and they are supposed to be identical, the first test I would make would be to open the breakers one at a time so that you are measuring only one string's output.
    If they are vastly different, you have a bad panel or a wiring error in the low string.
    If the power outputs are close (but not identical) and the Vmp of one string is different by 30 volts or so from the other while operating alone you have a bad panel. If the Vmp is different by more than 40 volts you probably have two or more bad panels. When you combine the output of the two strings in parallel the weak/defective string will not contribute much to the total even though it produces power on its own.

    That should get you started without having to mess with any wiring. Let us know the results. :)
    SMA SB 3000, old BP panels.
  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    Re: My Xantex System seems to have a peak output that is lower than I think it should be

    You could also increase your loads until your system voltage dropped, this should insure that even in absorb or float that you were using all available power from the panels, it might take a few minutes for the system to react...

    ... so run your heavy loads, a water heater, an air conditioner, start popping some pop corn in the microwave, max out your inverter... then check to see what the incoming use is.

    Not 'Coot but I take that as a compliment... though he might not :)
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: My Xantex System seems to have a peak output that is lower than I think it should be

    Welcome to the forum.

    Let me assure you first of all that changing the breakers (and why was this done?) will not alter system output unless the breakers are now undersized and tripping out, shutting things down. There is no way they will only limit current.

    Second, is this grid-tie or strictly off-grid? If it is not grid-tie your power output from the panels will be in direct relation to the amount used: lower loads = less production because there's no place for the power to go. If it is grid-tie it does all have a place to go and yet you have a drop in production of almost 20%.

    Which brings us to #3: the 3.36 kW hours vs. the 2.82 kW hours. Same time of year? If not don't expect an even comparison.

    Notes on your specs: in one place you say you have two rows of panels, then you say you have four strings per combiner box. How many combiner boxes and how many strings of panels t make that array? With twelve 240 Watt panels on a 48 Volt system I would expect eight strings of three panels in series to get the 5760 Watts. This could be four strings on each of two combiner boxes, which would work with one 60 Amp breaker per box. On a 24 Volt system this would also work, although the array Voltage would be running slightly high making more work for the charge controller.

    The array is significantly over-sized for 530 Amp hours of 24 Volt battery. You really only need about 1650 Watts for that (and only one controller). You've got enough array for 1840 Amp hours @ 24 Volts. Are you sure about the battery bank size?

    With an XW 4024 your power output (AC) will never exceed 4kW sustained. That would require 5200 Watts (or more) of array. The battery bank is also undersized for this, as it should be 200 Amp hours per kW of inverter for a 24 Volt system or 800 Amp hours minimum @ 24 Volts. The S-530 is in fact 400 Amp hours; are you sure you don't have eight of them? Two parallel strings of four in series would give 800 Amp hours @ 24 Volts and should work providing the charge settings are correct (high enough Voltage).
  • MJones
    MJones Registered Users Posts: 5
    Re: My Xantex System seems to have a peak output that is lower than I think it should be

    Hello,
    Thanks for your quick review and response. The answers to your questions are:
    1) Each row of the panels is 40 ft. They are wired to a junction box that goes to the breaker boxes and then into the MPPT 60 150. So from Junction box to MPPT, 25 ft is the distance
    2) I see the KW out on the screen that is on the Hybrid Inverter/Charger. It is consistent with the SCP display also. But your question got me thinking as there also displays on the 2 MPPT‘s. So this morning I noted each display. The Inverter read 2.67 kW. Each MPPT on the Output screen read 1339W, 26.5V 50.6A. On the MPPT System Screens it read 2766W 25.5 V, and 104.0A. (note they may not match as it took me time to record them and they were changing with the morning sun)
    3) The system was in BULK mode and the battery indicator read that the batteries were fully charged.
    4) No shade at all near panels.
    5) It is a system that is tied to the GRID.
    6) I have 2 rows of panels. My understanding is that each row has 4 ‘strings’ that come off of it (so 3 panels/string) and into each (2) combiner boxes where I have a breaker for each string.
    7) I think it is a 24V system and I have 4 batteries in the wooden box.
    8) The breaker was a 60 amp breaker and in mid summer it was tripping all the time so they replaced it with an 80amp ( I will double check this) breaker and, to me, limited the output so it would not trip any longer.
    I will try to the test to flip the breakers on 1 string and see what happens this weekend when I get home. If you have any other questions just let me know. It was 8am when I read the meters so the sun was just coming up.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: My Xantex System seems to have a peak output that is lower than I think it should be

    #8 - No; switching an 80 Amp breaker for a 60 Amp breaker will in no way affect the output of the system. The fact the 60 Amp was tripping repeatedly indicates current was exceeding 60 Amps at times.

    #7 - This could be a problem in itself as I described before. The battery bank being undersized can have an effect on power exported to the grid.

    #6 - Okay the physical outlay is two rows but you have eight strings in total. This makes sense.

    #5 - Good; always someplace for the power to go. So Watt hours should be approximate to total production.

    #4 - Also good, but time of year is a factor as well because sun angle changes through the months. Comparing August's output to January's is bound to show a discrepancy even near the Equator.

    #3 - In BULK mode the batteries are not fully charged. If the batteries have not been used for back-up since the last charge cycle the Bulk stage should be very short, as should the Absorb stage. Xantrex equipment, however, is not the best at handling this. But since we are looking at a change in operation we'll discount the Brand X Bugs.

    #2 - 1339 Watts from one controller + 1339 Watts from the other controller adds up to 2678 Watts. Pretty much just what the inverter read. Minor math errors can be discounted. The Voltages indicate this is a 24 Volt system.

    #1 - If one string has dropped out and you have eight strings you should see a drop of 1/8th output or 12.5%. The comparative numbers in the first post indicate almost 20%. But it is worthwhile checking this.

    Here's how:
    First, are the combiners equipped with fuses or circuit breakers? Breakers will be much easier to deal with for this.
    Second, the combiners are probably far from the display panels so you'll probably need two people and a form of communication between them. What you will be doing is disconnecting each string in turn and noting any change in controller output. This is why breakers are such a good idea here; each string breaker can just be turned off, then on again. If there are fuses you must cover all the panels in the string to drop its power output and see if that has any effect at the controller. The decrease should be 1/4 the power output of the controller.

    If a covered or turned off string causes no change in the controller output then something is wrong with that string and further investigation is warranted. Don't be surprised if there is no change and the difference is due only to sun angle change.

    Note: each controller has 2880 Watts of panel on it. On a 24 Volt system we'd expect to see a peak current of (2880 * 0.77 / 24) 92 Amps from that. This would easily explain why 60 Amp breakers were tripping, but would not explain why 60 Amp controllers were used when they would easily be overloaded as well. 60 Amps @ 30 Volts would be 1800 Watts which means each controller has 1000 Watts more than it can handle on it: a waste of panel.

    From what I'm seeing somebody did not set this up right. The 'cheapest' solution would be to up the system Voltage to 48, thereby reducing the current to levels the 60 Amp controllers can handle. This would mean adding batteries and changing the controller; not very cheap.
  • MJones
    MJones Registered Users Posts: 5
    Re: My Xantex System seems to have a peak output that is lower than I think it should be

    Hello Cariboocoot and Thanks,
    When you said “60 Amps @ 30 Volts would be 1800 Watts which means each controller has 1000 Watts more than it can handle on it: a waste of panel.” I think you nailed the problem.! One thing I do not understand is when he changed the breakers how did he change, or the system change, to lower the output from 3.36 to 2.82.
    I will check the stings this weekend but I think you nailed my problem! I do not think I will find any strings broken when I test that this weekend.
  • jcheil
    jcheil Solar Expert Posts: 722 ✭✭✭
    Re: My Xantex System seems to have a peak output that is lower than I think it should be
    The 'cheapest' solution would be to up the system Voltage to 48, thereby reducing the current to levels the 60 Amp controllers can handle. This would mean adding batteries and changing the controller; not very cheap.

    I tend to agree that this is in 48v territory for sure, but what about them just adding another controller and splitting the array into a 3rd one and staying at 24v?
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: My Xantex System seems to have a peak output that is lower than I think it should be

    The $1220 solution (I just checked the specs to be sure) is to replace both 60 Amp controllers with MidNite Classic 150's which can handle up to 94 Amps on a 24 Volt system. Might have a bit of 'clipping' from time to time, but not 1,000 Watts worth!

    Of course you'd have to upgrade the output breakers too. And you'd be faced with 180+ Amps of charge current which is far more than 400 Amp hours of battery can take so you'd have to increase the battery bank still. Even 800 Amp hours would be too small for that much current.

    In fact to reconfigure properly you'd go to 800 Amp hours @ 24 Volt battery (to handle the ripple current problem), use one Classic 150 and an array of around 2494 Watts. With the 240 Watt panels you could go twelve: four strings of three or half the array you have now. Max out the one controller and provide peak Watts around the 2.8 you have now, only not as often (makes me wonder if one of the controllers has suffered from over-current and isn't actually working).

    You can see here why a 4kW inverter ought to be 48 Volt especially for GT application. As it is the battery bank needs an 800 Amp hour minimum and to actually peak the inverter output at 4kW you get something like this: 5.2 kW array (normally runs about 77% efficient) producing 167 Amps peak current meaning a 1600 Amp hour 24 Volt battery bank. A lot of parallel connections there. If you up the system Voltage to 48 the current drops in half for the same amount of power: one charge controller, not two, 400 Amp hour battery minimum (better at 800) so fewer parallel connections, and slightly greater efficiency over-all.

    This should have been a 48 Volt system.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: My Xantex System seems to have a peak output that is lower than I think it should be
    jcheil wrote: »
    I tend to agree that this is in 48v territory for sure, but what about them just adding another controller and splitting the array into a 3rd one and staying at 24v?

    That could be viable too: buy another XW 60 MPPT and associated combiner box and wiring and output breaker. If we look at that we see 5760 Watts divided up as three 1920 Watt arrays (eight 240 Watt panels each; four parallel of two in series - lower array Vmp increases controller efficiency). Total output would be around 184 Amps (over 60 Amps per controller so still maxed out) and that is too much for the battery bank.

    I sure hope those batteries are okay.

    Maybe just remove some panels and sell them off.
  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    Re: My Xantex System seems to have a peak output that is lower than I think it should be
    MJones wrote: »
    8) The breaker was a 60 amp breaker and in mid summer it was tripping all the time so they replaced it with an 80amp ( I will double check this) breaker and, to me, limited the output so it would not trip any longer.

    ...Are you saying that they also reduced the output from the charge controllers? that could be your reduction right there.

    Producing 2700 watts in 'morning sun' isn't too shabby, Are your panels oriented to face south? I suspect they limited the output on your charge controllers, did the same person originally setup the system then come out and make the changes?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • SkiDoo55
    SkiDoo55 Solar Expert Posts: 414 ✭✭✭
    Re: My Xantex System seems to have a peak output that is lower than I think it should be

    Question as to set up on inverter? Are you selling to grid or just grid support? Are your production numbers from the the controllers to battery as asked before or the inverted production of the inverter? If sell got turned off then production would be totally dependent upon loads on inverter output.
    do you have 60 amp full rated breakers on input and output of each charge controller. Output of charge controller is limited to 60amp VDC by the controller. If the are using 1 input breaker for both controllers then at full load input you could have close to 70 amp. Should have separate breakers for each controller. In/Out.
    GT3.8 w/4600W Trina 230W, TX5000 w/5000W ET-250W, XW4024 w/1500W ET-250W, 4 L16, 5500W Gen. (never had to use) Yet!!
  • MJones
    MJones Registered Users Posts: 5
    Re: My Xantex System seems to have a peak output that is lower than I think it should be

    Hello Again,
    As you mentioned, this weekend I shut off each breaker from the lines that come from the PVs to see if any difference in the output was seen. For each breaker I saw an associated power drop so, as we suspected, all the PVs seem to be working. My next plan was to call Xantex customer support and tell them about our discussions and conclusions on this forum to see what upgrades I need. He asked me to check the input voltage to the MPPT which was 50v at the time! I was expecting 24v. He said that given the voltage and power we saw the MPPT 60 150 is within specs. He next told me to look at the 2 settings below on my System Control Panel (SCP). I saw the ‘from’ value and the ‘to’ value is what he instructed me to change it to. The first one he said was set wrong and was probably stressing the batteries. He then had me look at other settings and they looked fine. He said that these 2 settings would cause the output power to go up. Unfortunately, it was cloudy and raining here today so we could not verify it. It looks like rain for the next 2 days so Friday may be the first time where there is a chance for the output to go above the usual 2.86kw. I hope it doesn’t blow the breakers.
    I will keep you posted with the results when we get some sun. Any thoughts on what he has me doing?
    Again, Thanks for all you advice and council
    Merwyn
  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    Re: My Xantex System seems to have a peak output that is lower than I think it should be

    I have no chance to understand the 'from' and 'to' values? from and to where? the grid? the batteries, the inverter, the charge controller...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • MJones
    MJones Registered Users Posts: 5
    Re: My Xantex System seems to have a peak output that is lower than I think it should be

    Hi,

    Sorry for the confusion. I forgot to append that from my note :-(
    He had me change the Grid Support voltage (GSV) from 26v to 32v and the Charge Cycle: from 3 stage to 2 Stage No Float

    Sorry, Merwyn