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120-240 Dilemma- Growatt SPF 6000T DVM-MPV... Did I buy the wrong ALL in ONE?

Habilis

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Apr 27, 2022
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Hello there people more knowledgable than myself!!
Im the proud new owner of a Growatt SPF 6000T DVM-MPV. My decision to buy was based on powering our cabins 120V circuits 1st but having the robust ability to run our 240 V well pump as a bonus. The documentation from Growatt is confusing me... in the "AC Wiring" section of the manual it looks like I can do ONE OR THE OTHER but NOT BOTH. Also when I look at their diagram I find it odd there's not much mention of bonding or grounds... its occurring to me while I type... Did i buy a grey market gizmo that doesn't conform to NEC? Its been 35 years since I wired a house, so my skills are in the tank. Im asking here because Im having a little trouble getting Growatt to respond to my queries ?.
Thanks in advance for assisting old novice, any pointers on this issue truly apreceated!
Cheers
 

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Arguably, any unit that isn't UL1741 listed (I don't see that one is) isn't NEC compliant.

The wiring is definitely confusing. You can confirm for yourself if it's truly split phase with a VAC voltmeter:
L1-N: 120VAC
L2-N: 120VAC
L1-L2: 240VAC

you can also check for ground/bonding after turning the inverter off and checking continuity between N and G.

Good luck getting anything at all out of Growatt. Way better option to buy from a seller in the U.S. for support.
 
Growatt SPF 6000T is a low freq inverter with a center tapped large heavy weight output transformer.

They only provide L1 & L2 input for 240vac. The output has L1, L2 and neutral for 240/120v. When running with AC input, either grid or generator only connect up input to 240vac AC and leave generator/grid neutral not connected. Make sure you connect grid box or generator ground wire up to inverter ground input. Any grid neutral-ground bonding in main breaker box might cause a problem, explained below.

If you common connect an AC input 240/120vac neutral to output neutral you may have output transformer attempting to correct any imbalance in input 120vac L1-N or L2-N voltage. It likely will not be a big issue if AC input is fairly well balanced but for a generator input you just as well just leave its AC input neutral disconnected. The output transformer center tap provides the 240/120 vac split phase.

You don't get full power from a single 120vac AC side. You can get full power from 240vac or full power from both 120 vac sides summed together if they are balanced with same load current on each 120vac leg.

There should be an inverter setting for max AC input current. Make sure you set this appropriately for your generator or inverter may overload generator. The inverter will measure output load current and any charging AC current load and change charging to avoid overloading generator based on what you set for AC input current maximum.

As to the MPPT charge controller, the Growatt LF inverters SCC take PV directly to battery terminals on inverter.

LF hybrid inverter block diagram (2).png
 
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Believe this is diagram you are looking for. Be careful to only loosen the bottom terminal strip screws. The top screws go to internal inverter wires. Some folks have loosened both and shoved their connecting wire deep into terminal block driving the inverter internal wire out of the terminal block at the top.

SPF6000-T AC hookup.png
 
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Wow... this is really helpful, thanks so much for taking the time!
 
Arguably, any unit that isn't UL1741 listed (I don't see that one is) isn't NEC compliant.

The wiring is definitely confusing. You can confirm for yourself if it's truly split phase with a VAC voltmeter:
L1-N: 120VAC
L2-N: 120VAC
L1-L2: 240VAC

you can also check for ground/bonding after turning the inverter off and checking continuity between N and G.

Good luck getting anything at all out of Growatt. Way better option to buy from a seller in the U.S. for support.
Ha!
My local seller has yet to hire anybody that knows anything about Growatt gear. :-/
And
Thank you for your response.
 
Believe this is diagram you are looking for.
Excellent info in post 3, great diagram in post 4. (y)

This is the dilemma for me. What happens to Neutral when the generator is replaced by Grid Power?

EDIT: Question answered in post #9, suggesting "DON'T SUPPLEMENT WITH GRID POWER, USE A GENERATOR INSTEAD."
120-240 dilemma WYT.PNG
The diagram is simplified to focus on AC in. AC out is more complicated than shown.
 
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Excellent question.
i’m nowhere near a utility pole so I haven’t had to figure that one out. I did follow the guidance suggested by RCinFL (??) and am up and running with generator as shown in the diagram.
Now… configuring the damn thing. The documentation from Growatt is a sadistic joke IMHO. I bought SolarAssistant software and put it on a Raspberry pi… I just plugged it in and IT IS WORKING!
I’m now confident about 80% of the settings. A huge improvement from the bizarro LCD panel.
 
Per code, you cannot connect to grid because you need common neutral from grid neutral to inverter output neutral. All your existing house wiring outlets has their grounding and neutral bonded at main grid breaker panel.

If you common connect grid neutral to inverter output neutral the inverter output transformer will attempt to correct for any grid L1-N and L2-N voltage imbalance which will consume some of inverter output transformer power handling capability. This is same issue with autotransformers.

99% of time there is not enough imbalance on grid to cause significant inverter transformer neutral current. But, if it is significant it can damage inverter. Inverters like Xantrex, Outback, and Magnum monitor the neutral current and will release their connection to grid if it gets too significant of a load on inverter transformer. Low cost low freq inverters like AIMS, Growatt, etc. do not have this neutral current check.

Most all inverters have a temp monitoring of output transformer and will shut down inverter if it gets too hot, but this is slow reacting due to the mass of transformer to heat up. A sudden heavy neutral imbalance can saturate output transformer which will blow out inverter MOSFET drive devices.
 
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Believe this is diagram you are looking for. Be careful to only loosen the bottom terminal strip screws. The top screws go to internal inverter wires. Some folks have loosened both and shoved their connecting wire deep into terminal block driving the inverter internal wire out of the terminal block at the top.

View attachment 92882
I have been trying for months to figure out why my solar panels were not showing up on my display. After reading this post, I looked at my internal wiring and that's exactly what happened to my inverter. The internal wires were pushed out from the top screws. I'm up and running now. Thanks @RCinFLA
 
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