XW6048 and tristar problem

System
System Posts: 2,511 admin
in Grid Tie and Grid Interactive Systems #1
I have a Question that no one has been able or willing to answer for me, can someone Help??

My system consist of 15/190Watt evergreen Panels.a Xantrex 6048 and xantrex XW- mppt 60 , Working fine.
I added to the system,10/60watt Kaneka thin film solar panels(in Parallel) along with the Morningstar 60amp Charge controller. which is working well.
my problem is that any time the 6048 inverter charges the battery (at night) the Morningstar charge controller shows a red light and goes into Fault.
so I have to switch it of at night.
I also added a 48volt wind turbine with its 3 phase controller to the system. When the inverter begin charging the batteries it goes into dump mode which is what it is suppose to do when it see the high voltage.
Is there any way to have all 3 of these work together?
I notice that the tristar doesn't go into sleep mode when there is no load.it stays on all the time. can this be the problem?
thanks All.
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Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,631 admin
    #2
    Re: XW6048 and tristar problem

    What is the Battery Voltage and what is the XW 6048 charger set to charge at? Sounds like the charging voltage is set high... Also, what is the XW charger's maximum charge rate setting.

    Also, what size battery bank do you have--A small battery bank appears to be an issue when charging (voltage goes too high before chargers can "throttle back" the current).

    At a minimum, if you are charging/using 6kW of power, your 48 volt battery bank should be a minimum of ~600 AH capacity (20 Hour Rate).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    #3
    Re: XW6048 and tristar problem

    Something is pushing you battery voltage high , possibly an issue related to your Wind and XW charging the same bank?

    The TriStar Mppt HVD default is 62V ... you can use the MSView software

    http://www.morningstarcorp.com/en/support/product.cfm?Name=TriStar%20MPPT

    to adjust it, but I think you have other issues

    Also there is such thing as "sleep", if its not harvesting power its still functional ( web server and all), just the power electronics are turn-off ... its still has lower TAR loses than the MX/FM/XW chargers
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  • System2
    System2 Posts: 6,290 admin
    #4
    Re: XW6048 and tristar problem

    Thanks for your replies.
    I know that it's not the wind turbine, I took it off the battery bank and I still had the same Issue.
    recharge voltage 49.9V
    Absorb time 180 Min
    Grid support Voltage 54.7V
    Low batt cutoff 45V
    High batt cutoff 70V
    Maximum charge rate100%
    My battery bank is small 100AH( waiting for replacement
    I will post after I replace the batterybank
    tanks again.
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  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    #5
    Re: XW6048 and tristar problem

    For the XW, your grid-support is too high, 52V, especially with a 100ah battery bank would be advisable.

    Your probably having the issue with the inverter where for 30-45 seconds on undersized battery banks the battery voltage spikes up, 100ah is almost non-functional with a XW-6048 , I run 600ah and that's about as small as I would use if the loads running near the full 6kw rating of the inverter.

    As I said, you can change the TriStart's to a high HVD of your choosing, but all that will do is keep them online, not the real issue of your battery voltage spiking above the default 62V setting. Oh and if you do an EQ, not from the TriStar's, that would set off the HVD as well
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  • tallgirl
    tallgirl Solar Expert Posts: 413 ✭✭
    #6
    Re: XW6048 and tristar problem

    SG,

    Battery bank size is practically irrelevant with non-flooded batteries. The float charge on AGMs and Gels is so incredibly small that even with much larger banks of batteries, this problem is going to happen.

    The problem, as others have pointed out, is that the XW responds far to slowly, compared to the CC. At high states of charge, all batteries have the same exponential change in voltage for small increases in charging currents. Except that with VRLA's, it takes an even smaller increase in charging current to do that, and even with the battery type set appropriately, the CC will output entirely too much power into a fully charged battery bank. There's nothing that can be done about that -- VRLAs are just that much more sensitive at high SOC than FLAs.

    Lowering the sell voltage only works because it keeps the batteries from being full all the time. That strategy stops working as soon as the batteries =are= full, such as if the inverters disconnect from an AC over-voltage or loss of grid power and an Absorb cycle completes. And the only solution to that problem is reducing the Absorb voltage and time so that VRLA batteries don't actually reach their full state of charge. Which has its own set of problems.
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  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    #7
    Re: XW6048 and tristar problem

    The suggested sell voltage is to address AC ripple and the effects on the Mppt chargers, which with a ripple to large, the chargers can't track correctly

    As for the bank size, all one needs is a load that can sink about ~50 watts to keep the charge voltages in check. My understanding of the issue is this is resolution related on the AC current as the XW attempts to idle the charging for it 45 second timeout when voltages raise above its charger settings, it can't tell that ITS the one raising the voltage. After the timeout of min charge current is reached, it turns off the inverter ( charging is the inverter enabled ). This could be caused by being in Absorb or Float and the AC line voltage increases when the battery is fully charged

    With flooded or properly sized AGM's things work well, with 100ah of AGM's its an issue. Its not an issue of reaction time, it's an issue of trying to regulate below 1% of charge with undersized battery bank, at higher current levels its a non-issue

    52V is over 100% SOC ... not sure what you mean by your explanations to the contrary.
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  • boB
    boB Solar Expert Posts: 1,032 ✭✭✭✭
    #8
    Re: XW6048 and tristar problem
    tallgirl wrote: »
    SG,

    Lowering the sell voltage only works because it keeps the batteries from being full all the time. That strategy stops working as soon as the batteries =are= full, such as if the inverters disconnect from an AC over-voltage or loss of grid power and an Absorb cycle completes.

    If you are meaning, the typical 52V or so sell voltage, this sell voltage assumes that the batteries ARE full. Normally, on-grid, grid tie, where the batteries are not called upon to discharge very often, this is usually the case. (except for that once in a while Absorb or mini-EQ "boost")...

    So, the low sell voltage is really there to keep the batteries just above their natural OC voltage and to keep battery float losses at a minimum (higher system efficiency), and battery life at a maximum at the same time. Floating batteries all the time is not always a good thing for their life. Solar at least gives them a rest at night.

    boB
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  • tallgirl
    tallgirl Solar Expert Posts: 413 ✭✭
    #9
    Re: XW6048 and tristar problem

    SG,

    52 volts is "full" if and only if the batteries =are= full. Overnight losses, ripple, clouds, bad karma, and slow inverter reaction times all do a good job of insuring that 52 volts is likely not actually "full".

    And for what it's worth, the XW I'm currently fighting with has 675Ah of gel batteries. So ... not just a problem with tiny little banks. You might also want to look at manufacturer recommended trickle charge currents for Gels and AGMs because they are measured in small number of milliamps per amp-hour of capacity. 50 watts net is 1,000 milliamps, more or less.
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  • tallgirl
    tallgirl Solar Expert Posts: 413 ✭✭
    #10
    Re: XW6048 and tristar problem
    boB wrote: »
    If you are meaning, the typical 52V or so sell voltage, this sell voltage assumes that the batteries ARE full. Normally, on-grid, grid tie, where the batteries are not called upon to discharge very often, this is usually the case. (except for that once in a while Absorb or mini-EQ "boost")...

    So, the low sell voltage is really there to keep the batteries just above their natural OC voltage and to keep battery float losses at a minimum (higher system efficiency), and battery life at a maximum at the same time. Floating batteries all the time is not always a good thing for their life. Solar at least gives them a rest at night.

    boB

    When I've tested systems at low Sell voltages, I've found that the basic assumption that selling just above Voc (51.6 to, let's say, 52.4) maintains 100% SOC is incorrect. Typically those systems seem to reach equilibrium around 90% SOC, based on performing an actual Absorb cycle and using an appropriate return current as proof of 100% SOC, which is then confirmed by SG measurement.

    The reason, in part, is that there is a minimum voltage =above= Voc that is required to drive the charging reaction, but any voltage below Voc will cause discharge. Unless Vsell as at or above Voc + Vactivation, discharge naturally occurs over time.
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  • boB
    boB Solar Expert Posts: 1,032 ✭✭✭✭
    #11
    Re: XW6048 and tristar problem
    tallgirl wrote: »
    When I've tested systems at low Sell voltages, I've found that the basic assumption that selling just above Voc (51.6 to, let's say, 52.4) maintains 100% SOC is incorrect. Typically those systems seem to reach equilibrium around 90% SOC, based on performing an actual Absorb cycle and using an appropriate return current as proof of 100% SOC, which is then confirmed by SG measurement.

    The reason, in part, is that there is a minimum voltage =above= Voc that is required to drive the charging reaction, but any voltage below Voc will cause discharge. Unless Vsell as at or above Voc + Vactivation, discharge naturally occurs over time.

    Well, you have to make sure that the batteries were at 100% SOC BEFORE you go to that low sell voltage. My brain is multi-tasking this morning, so there may be something you are trying to say that I am not quite grocking. :D

    boB
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  • tallgirl
    tallgirl Solar Expert Posts: 413 ✭✭
    #12
    Re: XW6048 and tristar problem
    boB wrote: »
    Well, you have to make sure that the batteries were at 100% SOC BEFORE you go to that low sell voltage. My brain is multi-tasking this morning, so there may be something you are trying to say that I am not quite grocking. :D

    boB

    Coffee? You can has coffee?

    funny-pictures-your-cat-had-too-much-caffeine1.jpg

    What I mean is that the normal operation of a system, when the upper voltage is set below Vfloat, tends to discharge the batteries. Even if the voltage is held above Voc for SOC = 100%.
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  • boB
    boB Solar Expert Posts: 1,032 ✭✭✭✭
    #13
    Re: XW6048 and tristar problem
    tallgirl wrote: »
    Coffee? You can has coffee?

    ...kitty pic here...

    What I mean is that the normal operation of a system, when the upper voltage is set below Vfloat, tends to discharge the batteries. Even if the voltage is held above Voc for SOC = 100%.


    Ahhh,,. Yes... Correct.., Re-Float should happen once in a while.

    The point of low sell V though, is two fold. First, system efficiency is higher (PV to grid) and second, NOT floating the batteries all the time has been shown to increase their life.

    Selling somewhat above their open circuit voltage assures that you are not selling the batteries.

    Having said that, yes... The batteries should be given an Absorb charge once in a while if they haven't had one, to make sure they don't sulfate, (or the VRLA equivalent).


    boB
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