Growatt 12KW inverter seems to have a fundamental flaw.

SlyPhi

New Member
Hi all.

New to this forum, looking for help.

Some background:

I live 100% off grid in Australia.

I used to run a lead acid/ mpp solar system which did well, until it recently died in a very weird way (but that's another story) and found myself in the situation where I needed to install a Growatt 12kw system with a maxxcell 10kw lithium battery in a hurry.

Unfortunately a falling tree wiped out all but 3 of my panels and I can't get more for a few weeks, so I've been existing on 3 panels and generator backup, and herein lies the problem - the Growatt inverter refuses to charge the battery off the generator until the voltage drops to what ever it's defined in program 12 and the panels aren't enough to charge the battery to any great extent (it's winter here too). This might be fine for someone with a grid connection but for someone off grid this is absurd to the point that it makes the inverter almost useless. Frankly, when I turn my generator on, I want the damn battery charged no matter what the voltage in the battery is (obviously up to a point of course).

Seriously - this is a major flaw in the design of this inverter since there seems to be no way to turn this 'feature' off.

Has anyone found a firmware hack to kill this nonsense?

Would it be possible to use a stepdown transformer, a bridge rectifier and a large capacitor to take the 240v AC from the generator, turn it into 120VDC and simply jam it into the solar input? (apparently the solar inputs aren't hobbled in this stupid way like the grid input is)

I'm tearing my hair out over this because a system that cost close to $10K can't run a fridge overnight.
 

Groscout

Solar Enthusiast
My growatt goes full retarded when it has a trickle from the pv array and is plugged into grid/generator while trying to charge. Try switching the inverter off while charging with the generator. If that doesn’t do it try switching off your PV array as well. I’m still trying to figure out why mine goes from charging at 2 or 3 amps from the PV array and generator to 40a ‘as it should’ when I switch off the PV array via the combiner box and inverter off. I’m hoping someone with a better understanding of Growatt Mythology can elaborate.
 

SlyPhi

New Member
So its sound like the 12k Growatt is not that good? I was thinking of getting one to make my first 48v system.

To be fair it's early days for me on this inverter. I had a much smaller, much simpler MPP solar 3024 system running on lead acid that was fairly straight forward. The issues I'm having with the Growatt are related in part to my lack of panels - I'm pretty sure if you had 6kw of panels it would probably perform much better, however this issue with the 240v charging is frustrating as hell - so bad in fact that I couldn't recommend it to anyone who wanted to create a completely off grid solution. Forcing the AC to charge only in a certain set of circumstances and providing no other option is just dumb in my opinion, but I would love to hear from anyone who actually knows these inverters inside and out what they think - maybe I'm just missing something.

The documentation that comes with the inverter is pretty bad. Not enough information and badly presented.

I will say however that the support I got from my Australian supplier has been pretty good so far. They're unable to offer a solution yet, though not through lack of trying.
 

MurphyGuy

Solar Addict
Which "OPERATING MODE" do you have your system set to? Found this on page 24..

It says that "LINE MODE" will use the AC MAINS to provide power and charge the battery.
 

the_uglydog

Solar Enthusiast
I'm also in the process of ordering a Growatt 12kw off grid inverter to replace my Aims 10kw which has never worked correctly since new. I have a 8kw Growatt grid tie right now operating a different system that I had a couple of issues with. Here in The Philippines the grid voltage and hz are often way off. Sometimes the voltage gets as low as 169v and the hz varies from 58 to 61. I couldn't get the inverter to stay online. I have mine connected to the Growatt Shinelink system. On that you can adjust all the parameters on their inverters plus monitor everything from anywhere in the world. When I couldn't adjust things to work correctly they did it for me over the internet. My Growatt grid tie is the most dependable inverter I have and their support has been terrific! Their tech support is service@ginverter.com tell them everything including the model and where you are, they have different people for different parts of the world. That's about it. the dog
 

the_uglydog

Solar Enthusiast
To be fair it's early days for me on this inverter. I had a much smaller, much simpler MPP solar 3024 system running on lead acid that was fairly straight forward. The issues I'm having with the Growatt are related in part to my lack of panels - I'm pretty sure if you had 6kw of panels it would probably perform much better, however this issue with the 240v charging is frustrating as hell - so bad in fact that I couldn't recommend it to anyone who wanted to create a completely off grid solution. Forcing the AC to charge only in a certain set of circumstances and providing no other option is just dumb in my opinion, but I would love to hear from anyone who actually knows these inverters inside and out what they think - maybe I'm just missing something.

The documentation that comes with the inverter is pretty bad. Not enough information and badly presented.

I will say however that the support I got from my Australian supplier has been pretty good so far. They're unable to offer a solution yet, though not through lack of trying.
Actually is sounds a bit like what happens to my 2 Must 5kw inverters when they go into power saver mode. If there's a setting for that, take it out of that mode. Neither of mine will charge and they have a hard time restarting when they were in it. the dog
 

SlyPhi

New Member
Which "OPERATING MODE" do you have your system set to? Found this on page 24..

It says that "LINE MODE" will use the AC MAINS to provide power and charge the battery
I don't think this is settable. The inverter chooses the mode based on conditions I think. Regardless, when it's in 'Line Mode' it still seems to refuse to charge the battery from the generator unless the battery voltage is low.
 

SlyPhi

New Member
Actually is sounds a bit like what happens to my 2 Must 5kw inverters when they go into power saver mode. If there's a setting for that, take it out of that mode. Neither of mine will charge and they have a hard time restarting when they were in it. the dog
Yeah the switch on the front is a 3-way switch with a confusing array of options. ON (Power Saver), OFF (Inverter) and ON (Inverter). After talking to the Growatt support guy he said never use Power Saver because it doesn't do what you'd think it does, so I never have. The OFF switch isn't really an OFF switch, it just stops the 240V output and I've only ever run the inverter in the ON (Inverter) position.
 

SlyPhi

New Member
What are your inverter's settings, specifically:

Settings #
01 Output Source Priority
05 Battery Type
11 Max utility charge current
14 Charger source priority
01 - UTI
05 - USE (advised by Growatt tech, although I previously was running it on US2)
11 - 10 Amps. (The generator has duel 15A outputs but annoyingly the inverter can only select 10A or 20A, not 15A)
14 - SNU
 
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wattmatters

Solar Addict
That's what I'd suggest at this stage of your scenario.

05 - USE (advised by Growatt tech, although I previously was running it on US2)
There is a lithium battery option but requires communications with a compatible BMS.

If you have USE then you would have made adjustments to battery voltage settings 19, 20, 21. I guess just checking there's no issue with those settings as well.

11 - 10 Amps. (The generator has duel 15A outputs but annoyingly the inverter can only select 10A or 20A, not 15A)
This sets the upper limit at which the inverter will the cap charging current at. You could set it at 20A or 30A and if your generator can only supply 15A, it will take the 15A (provided the battery needs charge, if it's full-ish then the charge rate will drop).

Check setting 02 as well as that sets a global limit for charging from all sources.

That's charging with Solar and Utility.

While I agree you'd hope it would combine them, you might be right in that your limited array is causing problems. Try changing this setting to CUt - this is charging with utility only, solar used only when utility is not available. Hopefully this will enable the generator to charge the battery at a decent rate.

Also I note this about the inverter:

Screen Shot 2021-08-18 at 3.04.29 pm.png
So just make sure the inverter is not in Power Saving mode.
 

SlyPhi

New Member
There is a lithium battery option but requires communications with a compatible BMS.

Actually there seems to be 2 lithium battery options LI and US2. I was using the US2 option because the inverter will only talk to the BMS of a Growatt battery. When I was on the phone to the Growatt rep here in Aus he suggested using USE instead and we set up the appropriate settings in 19, 20 and 21 then. The Maxxcell battery I have has its own BMS between the input and the cells and manages any current on its own apparently so no communication is necessary. As far as I can tell, these options just omit all the different charging protocols necessary for lead acid batteries.

This sets the upper limit at which the inverter will the cap charging current at. You could set it at 20A or 30A and if your generator can only supply 15A, it will take the 15A (provided the battery needs charge, if it's full-ish then the charge rate will drop).

Check setting 02 as well as that sets a global limit for charging from all sources.

I went ahead and changed this to 20A and it then proceeded to charge at 20A (although the battery was low so no idea if it fixed my initial problem). It occurred to me though that is 20A is on the battery side not the generator side and so at 52V this would be ~1000VA. On the generator side 1000VA is only about 4A, so correct me if I'm wrong, but I assume I'd be able to draw up to ~3500VA on a 15A outlet and therefore could set the maximum charging amperage all the way up to 70A without tripping the RCD on the generator output?

The global limit for solar+util charge amperage is set at 80A which was both the default and what was recommended by the Growatt tech.

If I do end up trying these much higher charging amperages I will change the charge source to CUT for sure just to be safe.

So just make sure the inverter is not in Power Saving mode.

I assume this refers to the power saving mode on the 3 way switch on the front of the unit. I've never run it on this setting and was advised not to bother with it by Growatt.
 

wattmatters

Solar Addict
It occurred to me though that is 20A is on the battery side not the generator side
That's correct. It's setting the maximum DC current going to the battery.

but I assume I'd be able to draw up to ~3500VA on a 15A outlet and therefore could set the maximum charging amperage all the way up to 70A without tripping the RCD on the generator output?

DC Power Out = AC Power In x Conversion Efficiency. *

If your AC supply power is limited to 3500VA in and inverter conversion efficiency is say 90%, the power out (to the battery) is 3500 * 0.9 = 3150VA.

3150VA at a nominal DC charging voltage of 57V = 55A

To keep things inside limits, I wouldn't set the Utility charging current any higher than 50A.

* Edited formula to make more sense
 
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niktak11

Solar Enthusiast
My MPP solar unit has a separate setting for voltage that it will start charging from the grid. Does Growatt not have that?

Edit: Looks like #12 controls this. Maximum it can be set to is 51.2V though.
 
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Jgb3

Solar Enthusiast
I have a growatt 12k did you get this figured out? I didn’t read everything but i did have the same problem but fixed it
 

Jgb3

Solar Enthusiast
Well if anyone wants to know on mine it was the frequency that the generator was putting out with no load on it it was over 63hz so the growatt wouldn’t accept it( just gave me a blinking power pole) all I had to do was put my heat gun on it (or any load) to drop the frequency and I was good I even cranked the amps all the way up to test it out2B7E62C3-591E-407A-8AEA-133E55FC8D53.jpeg
 

SlyPhi

New Member
OK so I've had some luck but then ran into another couple of problems.

The unit settings that seem to work for me are:

01 - UTI
02 - 80A
03 - APL
05 - USE
06 - LTE
08 - 230
09 - 50
11 - 40
12 - 50V
13 - 56V
14 - SNU
19 - 57.6V
20 - 57.6V
21 - 48V
23 - DIS
24 - 57.6


The generator would charge the battery at a reasonable rate and seemed to be no longer refusing to charge only if the voltage was low (really I'm still mystified as to why this was happening).

The problems I then encountered were that some of the settings would be impossible to set - for example the setting in 12 is supposed to go to a maximum of 51.2V.. but this was impossible to set above 50V, though this is a moot point as 01 is set to UTI. Also the setting in 11 allowed you to change the least significant digit, but this would always go back to zero meaning you could only select multiples of 10 Amps for utility charging (no big deal but was kind of confusing).

The main problem I encountered was once the battery was fully charged, the inverter abruptly stopped putting out power and threw fault code 03 - Battery Voltage too high. When this happened I changed the charger source priority to OSO (only Solar), but even then my tiny PV array was able to trigger this condition which is concerning. I was instructed by Growatt to set 19 and 20 to 57.6V but I might drop it down slightly to see what effect that has.

The first of my replacement panels should arrive tomorrow and I'm hoping to have 9 out of 18 panels up and running by next weekend, so it will be interesting to see what happens with a bit more grunt coming in from the sun.
 

Jgb3

Solar Enthusiast
When I charged it with the generator once it shut off (fault code 03) I let the battery voltage settle back down then lowered the amps the generator could put in and charged it quiet a bit more at like 10-20 amps seemed to work cause it only took a few hours to top balance with a small bench top power supply
 
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