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Growatt 3000 SPF Floating Neutral (Solved for Now)

Found a fatal flaw I hadn't thought about. Growatt needs battery to turn on. It won't run on 120v input alone. We don't have solar yet. For some reason, growatt stopped charging batteries and when they ran dead we now have a houseboat with zero power. Generator and shore power are useless as growatt doesn't bypass 120v. It won't turn on without battery and we don't happen to have a 48v battery charger laying around.
 
yadaninetyone said:
Found a fatal flaw I hadn't thought about. Growatt needs battery to turn on. It won't run on 120v input alone. We don't have solar yet. For some reason, growatt stopped charging batteries and when they ran dead we now have a houseboat with zero power. Generator and shore power are useless as growatt doesn't bypass 120v. It won't turn on without battery and we don't happen to have a 48v battery charger laying around.
Click to expand...
Ironic, I came across this issue with the 3000 watt 24v version too. always running on battery, voltage dropped to the grid power trigger, not sure if it actually made it, as it was a night, then the batteries were off by BMS due to low voltage. The growatt could not be turned on via grid power. SOOO.... I will have to check to see if I have the latest firmware for it. How that dumb issue is fixed. Like how did that get past engineering as being ok?
 
I am trying to solve this Issue with ground bonding to get a natural gas furnace to start up. It needs a proper ground. The P/N on mine is SKDV06.CZ05302 (3000watt 24volt) Is the Grid to Output Neutral jumper the right thing to do here?
I have checked voltage on the output of the inverter from ground to L1 and Neutral, and they have either ~55 volts and ~75 volts when checked to ground. Will the neutral jumper which eventually gets bonded at the main panel short this out?
The unit is used primarily for Solar Battery operation, and will go to grid when battery empty. Growatt is connected to gride side with no GFCI with 6 feet of cable.
 
Aerial Gopher said:
I am trying to solve this Issue with ground bonding to get a natural gas furnace to start up. It needs a proper ground. The P/N on mine is SKDV06.CZ05302 (3000watt 24volt) Is the Grid to Output Neutral jumper the right thing to do here?
I have checked voltage on the output of the inverter from ground to L1 and Neutral, and they have either ~55 volts and ~75 volts when checked to ground. Will the neutral jumper which eventually gets bonded at the main panel short this out?
The unit is used primarily for Solar Battery operation, and will go to grid when battery empty. Growatt is connected to gride side with no GFCI with 6 feet of cable.
Click to expand...
Do you have the 24VGrowatt 3000SPF?

Aerial Gopher said:
I have checked voltage on the output of the inverter from ground to L1 and Neutral, and they have either ~55 volts and ~75 volts when checked to ground.
Click to expand...
Is that when the system is running from the battery or when it is running from the grid?
 
FilterGuy said:
Do you have the 24VGrowatt 3000SPF?


Is that when the system is running from the battery or when it is running from the grid?
Click to expand...
Yes SPF 3000TL LVM-24P and while it is on battery it has the voltages referenced from ground to Hot and Neutral. Should I check my multimeter? :p I was a bit confused by it.

From what I recall (been about 1 week since I tested this), when it goes to grid it does bond the output side neutral to ground, as its just passing the neutral through, and its bonded in panel. Ground always had continuity through input to output when in grid or battery mode.
 
Aerial Gopher said:
Yes SPF 3000TL LVM-24P and while it is on battery it has the voltages referenced from ground to Hot and Neutral. Should I check my multimeter? :p I was a bit confused by it.

From what I recall (been about 1 week since I tested this), when it goes to grid it does bond the output side neutral to ground, as its just passing the neutral through, and its bonded in panel. Ground always had continuity through input to output when in grid or battery mode.
Click to expand...
OK. You have the older version of the SPF 3000TL LVM-24P. Growatt told me it should be hooked up like this:

1661316171256.png
Notice that this turns the system into a common-neutral system.
 
FilterGuy said:
OK. You have the older version of the SPF 3000TL LVM-24P. Growatt told me it should be hooked up like this:

View attachment 108177
Notice that this turns the system into a common-neutral system.
Click to expand...
Thanks for clarifying, I will test it out tomorrow and see if the furnace turns on. Hopefully never need it but always nice to have the plan in place. Interesting though I have the old unit, as I just bought it a few weeks ago. :-( Seems like the new version had to have the external relay anyways, and seemed like more work. I am very happy with this one. Really quiet. I dumped an SRNE one which had 1 - 1.5 kWh per day losses for the inverter, and fans were so noisy at like 6000 RPM. Growatt is so much nicer! Live and learn.

Its funny that I use this big inverter for a 170 watt load, a network switch and also an additional 100 wats for monitors and laptop in office. BUT, sometimes need to use bigger stuff. Just playing with solar. My electrical bill was $2.04 last month so I guess its working out.
 
I apologize in advance for hijacking this thread (well kinda...). But this is one of the more comprehensive discussions here on the forum regarding this issue (N/G bonding).

A bit of background:
I recently bought a MUST 3kw 24v Hybrid inverter/charger (AIO model PH1800) via Aliexpress. This is a single phase 230VAC (European) Hybrid (grid-feedback capable) inverter.
I bought this model thinking that MUST is a big company and that this model is a Voltronic rebrand. Turns out it's not a Voltronic. It does has have very similar specs to MPP Solar 3kw Hybrids and the Growatt SPF 3000.
But, it only works with some proprietary software from MUST via USB (modbus RS485) and not with Watchpower.

Anyways, after extensive testing, I found that this inverter does NOT have ANY N/G bonding when in battery (off-grid) mode.
Things I've checked:
1. Inverter totally OFF - No continuity between AC out N/G.
2. Inverter connected to battery and producing AC out - same, no N/G bonding.
3. No menu option to change dry-contact behavior (can only be used as generator start signal when battery low).

When I contacted MUST via Aliexpress, they said it has to be done "manually" (stupid answer...).
I also asked if Neutrals can be connected together (like advised here) and they answered that their engineers don't recommend this.

My utility is probably TN-S (or maybe TN-C-S) so ground is not bonded in the main panel of my apartment, but it is bonded somewhere (either at utility transformer or at the building main utility entrance).

Any recommendations on what I can do ? I'm really stumped on this. I don't understand how they can release a Hybrid All-in-one without addressing this issue somehow.
Getting answers from MUST is really hard. I contacted them directly, but no answer. Only the seller on Aliexpress has been responding to my questions, but their answers are always really short and lacking any helpful information.

Since I will use this connected to grid AC and use both battery and solar (when available), I don't see how I can use an external relay when grid AC exists.
As for grid-feedback (grid-tie) usage, it would be nice to have, but I'm willing to give up on that feature if I can find a solution to the N-G bonding.
Thanks in advance for your help.
 
Is this inverter a grid-tied inverter? That changes things. (I didn't think it was)

Edit: everything i find on Google says off grid inverter.
 
timselectric said:
Is this inverter a grid-tied inverter? That changes things. (I didn't think it was)

Edit: everything i find on Google says off grid inverter.
Click to expand...
Mine (MUST PH1800) is basically an AIO that functions like most common off-grid AIOs, but has a menu option to enable grid feed-back of any excess solar power being produced (after powering loads and recharging the battery).
 
meetyg said:
...

My utility is probably TN-S (or maybe TN-C-S) so ground is not bonded in the main panel of my apartment, but it is bonded somewhere (either at utility transformer or at the building main utility entrance).

Any recommendations on what I can do ?...
Click to expand...
Being that you state you live in a apartment before you do anything to your electrical system you should have the approval of the owner.

Normal setup for these off grid inverters is to wire "AC out" to a sub-panel and not the Main. "AC in" is supplied by the Main by a breaker and passed through (thus providing the NG bond) to the sub which does not have common NG setup. In inverter mode if the unit does not create a NG bond your sub-panel would need to do so.

Sounds like this unit will not work for you.
 
Mattb4 said:
Being that you state you live in a apartment before you do anything to your electrical system you should have the approval of the owner.

Normal setup for these off grid inverters is to wire "AC out" to a sub-panel and not the Main. "AC in" is supplied by the Main by a breaker and passed through (thus providing the NG bond) to the sub which does not have common NG setup. In inverter mode if the unit does not create a NG bond your sub-panel would need to do so.

Sounds like this unit will not work for you.
Click to expand...
Sounds like many of these AIO won't work for many people (other than pure off-grid or grid backup/UPS).
 
HLDMYBR said:
Can anyone link to a good external relay on Amazon that would take care of this task?
Click to expand...
Is your installation stationary or moblile? If you have a stationary set-up you might not even need a relay. Just hook the Input neutral and the output neutral.
 
FilterGuy said:
Is your installation stationary or moblile? If you have a stationary set-up you might not even need a relay. Just hook the Input neutral and the output neutral.
Click to expand...
It's mobile, but I need to be able to plug in to grid or generator once in a while.
 
@FilterGuy , I see here that tying input and output neutral with this unit is acceptable for units that do not have an internal ground neutral bond( mine do not)

is this still acceptable? with two units would one tie both output neutrals to the input neutral?
Is there any possibility of this backfeeding the grid? I read a post from you where MPP said not to have common neutrals because of the possibility of backfeeding the grid
 
1201 said:
@FilterGuy , I see here that tying input and output neutral with this unit is acceptable for units that do not have an internal ground neutral bond( mine do not)

is this still acceptable? with two units would one tie both output neutrals to the input neutral?
Is there any possibility of this backfeeding the grid? I read a post from you where MPP said not to have common neutrals because of the possibility of backfeeding the grid
Click to expand...

Growatt has been all over the map on whether this is supported, so it is hard to say what they deem acceptable.

By reports from others and even from Growatt in one isolated instance, it appears to be OK.

Other brands of very similar models say it is OK.


Meanwhile: I thought we decided your inverter does do the bonding internally....???
 
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