Help wanted-Growatt/MPPT users.

apctjb

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Trying to troubleshoot an issue and hoping that other Growatt/MPPT owners might be able to help.

Does anyone know what triggers the inverters to stop solar charging after reaching float voltage and what triggers them to resume charging?

Is charge termination and resumption based on voltage setpoints, elapsed time, SOC, or something else and are they user adjustable?

The issue I am observing is that once PV charging stops after float voltage is reached it can take a long time for charging to resume, sometimes more than a day. I have a 560AH LiFePO4 battery and loads are modest so voltage is not changing much. But rather than drawing energy from the battery it would be nice to have solar meeting the load, but that only happens when the inverters are in charging mode. Once they stop charging they draw energy from the battery regardless if solar is available.
 

apctjb

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273
No takers?

No charging again this morning despite full sun. Battery remains close to fully charged as nightime loads are minimal, regardless I would assume that each morning the charge controller would resume charging cycle, even if it quickly when to absorption and float. But perhaps not, and it is waiting until battery voltage drops to some setpoint (and I wish I new what it was) before resuming charge cycle.

Anyone else have an issue where there all in one Growatt or MPP does not attempt to charge every morning?

1615130133981.png

If I turn the inverter on/off it will immediately start charging, and charge normally until it reaches "full charged" so I know the MPPT charger works.

Another thing that puzzles me, why would a inverter/charger designed for off grid solar ever go into a fully charged mode and stop charging altogether rather than staying in float?
 

Joe BoyKey

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My Growatt SPF-6000T-Dvm is set to Bulk up to 56.4 and float at 54.6v, so when Batteries are charged at 56.4 it shuts off Solar till Batteries get down to 54.6 - float, takes about 20 min on a sunny day. Then Solar kicks back in to float along at 54.6 and handle all loads, Joe.
 

Zwy

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Jan 3, 2021
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845
No takers?

No charging again this morning despite full sun. Battery remains close to fully charged as nightime loads are minimal, regardless I would assume that each morning the charge controller would resume charging cycle, even if it quickly when to absorption and float. But perhaps not, and it is waiting until battery voltage drops to some setpoint (and I wish I new what it was) before resuming charge cycle.

Anyone else have an issue where there all in one Growatt or MPP does not attempt to charge every morning?

View attachment 39952

If I turn the inverter on/off it will immediately start charging, and charge normally until it reaches "full charged" so I know the MPPT charger works.

Another thing that puzzles me, why would a inverter/charger designed for off grid solar ever go into a fully charged mode and stop charging altogether rather than staying in float?
You need to list your settings if you want answers. All the way from #1 thru #24. This video might help also.
 

apctjb

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273
You need to list your settings if you want answers.
Settings are all factory default except for #5 battery type which is set to use2. Full list of settings shown below.

Obviously settings 19,20 (Absorption voltage, Float Voltage) influences when the charger goes from bulk to absorption and then from absorption to float. But my question is what influences how long the charger stays in float before resuming bulk or stops charging altogether (my situation) and after it stops charging what setting influences when it resumes? Is anyone else seeing there solar charger not kick in the next morning and start the charging cycling if solar is available? I am going on third day with no charging and I am trying to understand if that is normal or somethings up.
1615142311361.png
1615142406372.png
 

apctjb

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Messages
273
My Growatt SPF-6000T-Dvm is set to Bulk up to 56.4 and float at 54.6v, so when Batteries are charged at 56.4 it shuts off Solar till Batteries get down to 54.6 - float, takes about 20 min on a sunny day. Then Solar kicks back in to float along at 54.6 and handle all loads,

Interesting that it stops after bulk and resumes at float. On mine when it reaches Bulk it starts to throttle down charging (Constant voltage mode) until float voltage is reached, then it stays in float voltage for a period of time and then charging stops altogether. What I am hoping to figure out is what setting controls when it stops charging after having been in float and what setting adjust when it resumes.
 

Joe BoyKey

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Switch to use, had the same problem before, it will fix it, Joe
I don't have compatible batteries/BMS, Ian had me switch to use2 and I had the same problem, switch to USE
 

apctjb

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I don't have compatible batteries/BMS, Ian had me switch to use2 and I had the same problem, switch to USE

I had it set to USE initially and when it wasn't working Ian had me switch to USE2.

When you say you had the same problem do you mean that once the batteries reached float they would stop charging and then not resume charging or something else?

I wonder if me having Bulk and Float set lower than your 56.4 is a factor. I tried setting mine up but have one cell that starts running away and triggers the BMS so had to reduce the upper voltage setting as did not want the BMS acting as a charge controller.
 

Joe BoyKey

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Changed to use2, the next morning noticed no solar charging, (gap in blue) voltage at cut off was 53.5v, Batteries not charged, switched back to use and restarted inverter, never had the problem again. My smart Lifepo4 batteries all stop charging on their own when the controller walks voltage up to 56.4v.
1615146955775.png

1615148253774.png
 
Last edited:

Tired Old Man

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Feb 19, 2021
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Interesting that it stops after bulk and resumes at float. On mine when it reaches Bulk it starts to throttle down charging (Constant voltage mode) until float voltage is reached, then it stays in float voltage for a period of time and then charging stops altogether. What I am hoping to figure out is what setting controls when it stops charging after having been in float and what setting adjust when it resumes.
The battery voltage ?
 

apctjb

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Joe BoyKey; Thank you for sharing your settings, very helpful. 56.4 is too high for my LiFePO4 bank as one cell is kicking out the BMS if I bring the battery that high. So I have mine down to 54. I wonder if that is part of the problem as lower voltage setpoints puts me in the flatter part of the battery voltage curve and with 560AH my batteries can hang at 53.5 volts for days....
 

Joe BoyKey

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Sounds like You need to top balance your cells, not knowing what kind of Batteries you have - one can only guess. Mine are all Lifepo4 Smart batteries with built in BMS and they take care of themselves, you have battery specs, post them for real help, Joe.
 

Zwy

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845
Settings are all factory default except for #5 battery type which is set to use2. Full list of settings shown below.

Obviously settings 19,20 (Absorption voltage, Float Voltage) influences when the charger goes from bulk to absorption and then from absorption to float. But my question is what influences how long the charger stays in float before resuming bulk or stops charging altogether (my situation) and after it stops charging what setting influences when it resumes? Is anyone else seeing there solar charger not kick in the next morning and start the charging cycling if solar is available? I am going on third day with no charging and I am trying to understand if that is normal or somethings up.

View attachment 39980
View attachment 39981
You didn't watch the video, did you? You have UTI set on #1.
 

apctjb

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You didn't watch the video, did you? You have UTI set on #1.

Have tested it with UTI, SOL or SBU , doesn't appear to have any impact when utility is not present. Ian suggest I leave it at UTI
 

apctjb

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Note; if I take the inverters out of parallel mode then both charge normally. Put them back into parallel mode, one stops charging and then neither resume charging the next morning.

The problem appears related to parallel operation, which in my application is needed.
 

Joe BoyKey

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Make sure your solar arrays are seperate, never have a common ground, ie.. 1 set of panels to one charge controller and he other array to the other controller - no common wires on the panels, just a thought, Joe.
 

apctjb

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Make sure your solar arrays are seperate, never have a common ground, ie.. 1 set of panels to one charge controller and he other array to the other controller - no common wires on the panels, just a thought, Joe.

Very interesting thought. I had posted previously asking about the issue of having PV negatives tied and all the responses were it would not be an issue. I only have 1 charging relay with my BMS so that poses a new problem with lots of rewiring.

Do you know why having PV negatives common is a problem for Growatt?
 
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