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Using Multiple Growwatt 5kw as backup on (manual) transfer switch wiring (Floating neutrals?)

hipringles

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Is there a standard wiring diagram out there? My current short term plan is to use the existing generator lockout switch to connect the inverters to, then also wire in a nema 14-50 as a plug-in charger for the inverters.

Would I just wire it up per the obvious panel way:
  • inverters go to *inverter only* sub panel to "combine" into 1 output?
  • Breaker from that connects to main panel generator lockout breaker
  • Bond the neutral & Ground from sub-panel to the real main
Should I use an ATS system instead? And is just putting a 14-15 plug to connect the inverter IN to the simple answer? These are the exact inverters
 
Do you plan on using a transformer for 120V loads? Assuming yes.
Backfeeding the main panel through a generator interlock and two pole CB will be a problem because of the neutral-bonding problem.
ETA:
Deleted my second sentence, I think I'm wrong, I neglected to consider one situation.

Lots of discussion here:
https://diysolarforum.com/threads/d...pf-5000-es-grid-backup-neutral-bonding.29717/

And here:
https://diysolarforum.com/threads/growatt-spf-5000-es-wiring-for-0-export-need-help.28401/
 
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Do you plan on using a transformer for 120V loads? Assuming yes.
Backfeeding the main panel through a generator interlock and two pole CB will be a problem because of the neutral-bonding problem.
Better idea is to install a dedicated downstream panel, pull over the critical circuits to that panel, use the utility pass through of the inverters for primary power and not pulling over a grid neutral to the new derived panel.

Lots of discussion here:
https://diysolarforum.com/threads/d...pf-5000-es-grid-backup-neutral-bonding.29717/

And here:
https://diysolarforum.com/threads/growatt-spf-5000-es-wiring-for-0-export-need-help.28401/

"Because of the neutral-bonding problem"


What specifically do you mean? My current plan is to have a sub-panel with the 2-3 inverters, transformer, then a main out that goes to a *plug* that will be physically plugged into the generator interlock.

So there will be 1 set of 4 wires (L1 2 N G) connecting to the generator interlock plug, only when using the backup power.

I am guessing the problem has to do with the auto-transformer and the connection between the main panel and the grid neutral?
 
Those generator transfer panels do not switch the neutral. You are splicing in-line to the hot side only.
You'll have a problem connecting an inverter autotransformer to an operating grid panel because you'll end up with multiple neutral bonding points. You'd need a way to switch the neutrals if everything is connected to the same panel.
Discussed in the links I posted.

Transfer panel instructions
http://d163axztg8am2h.cloudfront.net/static/doc/59/45/3008297150d87fc1a26f87fe0a5f.pdf
for sake of instructions, I posted my idea of setup on the other thread
 
Also, that type of panel is an older legacy design.
Since you are not pulling over the neutrals, the magnetic field from the hot is not cancelled out, so the induced currents in the metal case is higher and the dissipation to ground is critical.
 
Also, that type of panel is an older legacy design.
Since you are not pulling over the neutrals, the magnetic field from the hot is not cancelled out, so the induced currents in the metal case is higher and the dissipation to ground is critical.
Curious on your thoughts on a fully connected (through a plug that is only connected when the main is off) 4 line (1/2/N/G) system where the subpanel (that has only the inverters/transformer) is also bonded
 
I edited my original posts, there is a scenario I had neglected to consider and my opinion was wrong based on it.
 
I am using 2 of these manual transfer boxes for 10 circuits each. They are fed by 2 solar arrays and 2 different inverters. It has rocker switches so there is never a way to have solar power on at the same time as grid tied power.
I was looking at a similar product but from reliance controls. I have used one in the past (protran/2), and to be honest I really liked it. I had full control over the loads. An ATS based system removes some of that flexibility IMO. I know this because I replaced it with a generac ATS, and I had to be around when the power went out or risk overloading my genset until I got the 16k unit in. In ATS driven systems you must assume you won’t be home when it happens and that also everything that can turn on will turn on. This goes for solar or genset based things.

i think if I am capturing your question correctly, you want to use the inverter as an SDS. This will work with these types of panels, and you can bond you neutral to ground. But you could not in turn connect that back into your main panel on an interlock. You either provide a full SDS or you do not. You either switch to the SDS completely or you do not.

@Desert_AIP is correct.

Bonding can only be done in one place, and the mentioned (protran/2) panel style switches the hot leg, thus disconnecting the bond provided at the service entrance. They are designed to support the usage of portable generators as a source of backup power as many of them as neutral bonded.
EDIT: The protran/2 does not switch the neutral leg, it switches the hot leg. I honestly don't know how this thing made it through UL

if you are looking to use an interlock I suggest following along in the thread @Desert_AIP mentioned, we do have quite a good conversation going there.


We are working on exactly that. We want to build out a few scenarios and the publish wiring charts that are simple to follow.

There are charts available in the thread address things such as lost neutral (because what happens when the auto transformer fails).

With these units, you cannot get usable power for anything other than 3 wire 240 circuits without an auto transformer. (L1/L2/G). If that is all you plan to run, then you can pretty much disregard this whole post.


*edits due to the horrible keyboard on my ipad
 
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