Need help. Will this breaker setup work for my design?

[SniperX]

I have a 100A main panel for the solar shed. All loads are on this but the panel is full and cannot take another breaker. I have a Growatt 12kw AIO 250V 120A and the manual says to use a 80A breaker between the inverter and the panel. Normally, you would put the breaker in the panel BUT 80A is over the 50% threshold for the panel and even if that was not a factor, the panel is full (the husband bought the panel before asking what was needed)

To complicate things, my system is off-grid. I want to power this panel either by a Honda ES7000is generator OR the Growatt 12kw (with solar and 6 EG4 48V 100A batteries) so I have an EATON 100A manual transfer switch. Right now, the main power input is wired to the generator, but I am trying to install the Growatt and I am not sure how to proceed.

Question: Since my panel is full and I am going to a transfer switch, can I put the breaker between the transfer switch and the inverter like the black arrow in the picture? I would need to put that on a rail of some sort and put a box around it, but would this be acceptable? So Growatt 12kw wired to the 80A breaker, then the breaker wired into the bottom of the transfer switch. The generator wire is pulled from the panel and wired to the top of the transfer switch and then in the middle of the transfer switch, those wires then go to the top of the fusebox for the main fuse.

The Growatt 12kw can only accept 6 AWG wire (I wish I could put 4 AWG for AC but 6 AWG is the max) and this is what is keeping me awake at night. 6 AWG is rated for around 105 A (wire rated at 90 degrees C) and they want an 80A breaker. Would this wire size be ok for 120A the Growatt could provide if maxed out? 4 AWG would be better because it is rated at 140AWG at 90C.

I have been all over the place trying to find out what to do and I am on overload and getting overwhelmed.

The fusebox photos show the red/black wire going into the main 100A breaker and that is currently the wiring for the generator plug outside the shed. That wire would move to the top of the top portion of the transfer switch and then the middle row of the transfer switch would be wired with 6 AWG (or I could use 6AWG to transfer switch from Growatt 12kw and then use 4 AWG going from the transfer switch to the panel) back to the main 100A breaker on the panel. The bottom row of the transfer switch would be for the Growatt but it has to be 6 AWG. I need to know if the 80A breaker can go to the right of the transfer switch and before the Growatt 12kw to satisfy the manual's instructions to have an AC breaker. All ground (green wires) would go to a mechanical lug which would then go back to the ground in the main panel. I have a double plug on order since that is a single one and you can only put 2 wires in on connection for those. I will change that out when it gets here.

I know generally they wire the AC input on the Growatt for a generator but we want to be able to run strictly on the generator or strictly on solar/battery, so I think the transfer switch is the solution but I am open to anything at this point.

I can buy another panel, but my transfer switch is rated at 100A and so, in order to get that 80A breaker, I would need a 200A panel, and then the 100A panel would be a sub-panel... and would the 100A transfer switch work with that? I am lost at this point. Thanks for trying to help me.

The drawing is terrible, but not too computer savvy. I have a Growatt 48120 SCC and some have suggested running the main pv array to that but do I hook that to the battery rack or does it go to the main Growatt? It is not connected to anything in the picture but I wanted to get my answers in stages so I am not frying my brain.

I also have questions about the wire size for the battery to Growatt. Manual states 3*2awg (I was going to use 4/0 but it is not rated for the same amount of amps at the 3*2AWG so wondered if 2*2/0 would work)
Manual found here for Growatt 12kw

 

[BentleyJ]

I have a 100A main panel for the solar shed. All loads are on this but the panel is full and cannot take another breaker. I have a Growatt 12kw AIO 250V 120A and the manual says to use a 80A breaker between the inverter and the panel. Normally, you would put the breaker in the panel BUT 80A is over the 50% threshold for the panel and even if that was not a factor, the panel is full (the husband bought the panel before asking what was needed)

You could use Fuses instead. Ya, I know the next question is "what kind". Lets work through these questions first. EDIT: See below regarding replacing the 100A panel all together.

To complicate things, my system is off-grid. I want to power this panel either by a Honda ES7000is generator OR the Growatt 12kw (with solar and 6 EG4 48V 100A batteries) so I have an EATON 100A manual transfer switch. Right now, the main power input is wired to the generator, but I am trying to install the Growatt and I am not sure how to proceed.

Plan A: Since the Honda will presumably produce good clean power that is acceptable to the Growatt, I would connect the Generator directly to the Growatt AC Input then the 100A panel can be powered via pass-thru AND could charge the batteries if needed when solar production is poor.

Plan B: Use the transfer switch to connect both sources of power so you can switch back and forth. In this case the generator could still be used to charge batteries you would just need a separate 48V charger to plug directly into the gen or outlet connected to the 100A panel. Basically the same as using a 12V automotive charger for your car battery.

Plan C: See Plan A. Then if the Growatt fails its not that difficult to move the Gen wires from the inverter AC input to the transfer switch to power the 100A panel. The Growatt could be sent out for repair or replacement.

Question: Since my panel is full and I am going to a transfer switch, can I put the breaker between the transfer switch and the inverter like the black arrow in the picture? I would need to put that on a rail of some sort and put a box around it, but would this be acceptable? So Growatt 12kw wired to the 80A (or should it be 60A for wire) breaker, then the breaker wired into the bottom of the transfer switch. The generator wire is pulled from the panel and wired to the top of the transfer switch and then in the middle of the transfer switch, those wires then go to the top of the fusebox for the main fuse.

Fuses

The Growatt 12kw can only accept 6 AWG wire (I wish I could put 4 AWG for AC but 6 AWG is the max) and this is what is keeping me awake at night. 6 AWG is rated for around 105 A (wire rated at 90 degrees C) and they want an 80A breaker. Would this wire size be ok for 120A the Growatt could provide if maxed out? 4 AWG would be better because it is rated at 140AWG at 90C.

The manual "recommends" 6 AWG which is too small for an 80A breaker. 4AWG would be the minimum. Are you sure the terminal block will not accept 4AWG wire There are pin style reducer compression lugs that will downsize the wire from 4 to 6. Honestly, if the Growatt is so poorly designed that the terminal block cannot accept the proper wire what else is wrong with it?

I have been all over the place trying to find out what to do and I am on overload and getting overwhelmed.

Relax. There are solutions.

Generator wire would move to the top of the top portion of the transfer switch

Yes

and then the middle row of the transfer switch would be wired with 6 AWG (or I could use 6AWG to transfer switch from Growatt 12kw and then use 4 AWG going from the transfer switch to the panel) back to the main 100A breaker on the panel.

Yes, #4 as long as its protected upstream with an 80A Fuse and the generator has its own protection built in. The 100A panel breaker simply becomes a connection point, not an over current protection device.

The bottom row of the transfer switch would be for the Growatt but it has to be 6 AWG. I need to know if the 80A breaker can go to the right of the transfer switch and before the Growatt 12kw to satisfy the manual's instructions to have an AC breaker.

Yes bottom of the transfer switch, 4 AWG is needed for 80A. Fuse or breaker could be mounted to the right of the transfer switch.

I know generally they wire the AC input on the Growatt for a generator but we want to be able to run strictly on the generator or strictly on solar/battery, so I think the transfer switch is the solution but I am open to anything at this point.

If the generator is wired into the Growatt you should be able to choose Source Priority as Utility first and then disable the internal charger. Power would pass through the Growatt but you would essentially be on Gen only at that point. Either way will work, direct wire to Growatt or transfer switch.

I can buy another panel, but my transfer switch is rated at 100A and so, in order to get that 80A breaker, I would need a 200A panel, and then the 100A panel would be a sub-panel... and would the 100A transfer switch work with that? I am lost at this point. Thanks for trying to help me.

100A or 125A subpanels are relatively low cost. I would look at getting another subpanel, 20 space, without a main breaker at all. These are called main lug panels. Then you can install a standard 2 pole 80A breaker, back-feed that from the transfer switch and install all the other branch breakers for your existing loads and probably have a couple spare breaker slots. EDIT: This eliminates the Fuse/Breaker issues asked about above.

The drawing is terrible, but not too computer savvy. I have a Growatt 48120 SCC and some have suggested running the main pv array to that but do I hook that to the battery rack or does it go to the main Growatt? It is not connected to anything in the picture but I wanted to get my answers in stages so I am not frying my brain.

The Growatt has a built in charge controller and will accept up to 7000W of PV panels. If you wish to use the SCC alone or in combination with the Inverter then its output gets connected directly to the batteries. Although you could use a central bus bar to make all the Low Voltage DC connections then wire from the bus bar to the inverter, SCC and batteries.

I also have questions about the wire size for the battery to Growatt. Manual states 3*2awg (I was going to use 4/0 but it is not rated for the same amount of amps at the 3*2AWG so wondered if 2*2/0 would work)

I would use 3/0 Class M or K welding cable. Fine strands make it much more flexible and easier to work with.

 

[SniperX]

Relax. There are solutions

I just exhaled seeing your answers so before I dive in- T H A N K YOU!

 

[SniperX]

The manual "recommends" 6 AWG which is too small for an 80A breaker. 4AWG would be the minimum. Are you sure the terminal block will not accept 4AWG wire There are pin style reducer compression lugs that will downsize the wire from 4 to 6. Honestly, if the Growatt is so poorly designed that the terminal block cannot accept the proper wire what else is wrong with it?

I DON'T want to know. I bought it right after watching Will Prowse sing its praises. He promised a follow-up video to wire it. I would not have even jumped into all this if I had not seen that video and figured Will would explain things so I could understand, but then the grounding controversy happened with the Growatts and Will dropped them like a hot potato. I am stuck with this purchase and I own my $2400 mistake.

 

[BentleyJ]

I DON'T want to know. I bought it right after watching Will Prowse sing its praises. He promised a follow-up video to wire it. I would not have even jumped into all this if I had not seen that video and figured Will would explain things so I could understand, but then the grounding controversy happened with the Growatts and Will dropped them like a hot potato. I am stuck with this purchase and I own my $2400 mistake.

There are quite few people successfully using Growatt. Just have to work through each question and issue till its done.

 

[SniperX]

The manual "recommends" 6 AWG which is too small for an 80A breaker. 4AWG would be the minimum. Are you sure the terminal block will not accept 4AWG wire There are pin style reducer compression lugs that will downsize the wire from 4 to 6. Honestly, if the Growatt is so poorly designed that the terminal block cannot accept the proper wire what else is wrong with it?

Someone on this forum said he replaced the busbar on the Growatt with something else to accept the 4AWG wire and replaced the breakers in the Growatt 12kw. That is over my head unless I can see a picture. I work better mentally with a picture since I am more artistic than linear. I am left-handed, lol. Anyway, I don't know how to find such a thing, and if I did, I don't know what rating I am looking for. Does that sound like an easy thing? I just take the cover off and put a new mechanical bar lug thing that will accept 4AWG and then wire 4 AWG from it? I just came across that idea a few days ago and no one has done this but that guy and he just mentions it. I saw a video Will did on the EG4's saying to use 4AWG which is why I researched it and came to the conclusion I should do this but can't. It can barely take 6 AWG.

 

[SniperX]

If the generator is wired into the Growatt you should be able to choose Source Priority as Utility first and then disable the internal charger. Power would pass through the Growatt but you would essentially be on Gen only at that point. Either way will work, direct wire to Growatt or transfer switch.

I am not the only one who may have to use this system, so the transfer switch would be the easiest. Harder to screw up. I don't think my husband would be able to get into the program and change things. It would be easier if he flipped a switch and turned the generator on. Honest answer.

 

[BentleyJ]

Someone on this forum said he replaced the busbar on the Growatt with something else to accept the 4AWG wire and replaced the breakers in the Growatt 12kw. That is over my head unless I can see a picture. I work better mentally with a picture since I am more artistic than linear. I am left-handed, lol. Anyway, I don't know how to find such a thing, and if I did, I don't know what rating I am looking for. Does that sound like an easy thing? I just take the cover off and put a new mechanical bar lug thing that will accept 4AWG and then wire 4 AWG from it? I just came across that idea a few days ago and no one has done this but that guy and he just mentions it. I saw a video Will did on the EG4's saying to use 4AWG which is why I researched it and came to the conclusion I should do this but can't. It can barely take 6 AWG.

I believe we can find comprssion pin lugs to reduce from 4AWG to 6. Give me a few minutes.

 

[SniperX]

Plan B: Use the transfer switch to connect both sources of power so you can switch back and forth. In this case the generator could still be used to charge batteries you would just need a separate 48V charger to plug directly into the gen or outlet connected to the 100A panel. Basically the same as using a 12V automotive charger for your car battery.

Was considering the Chargeverter by SS but too many people have asked for better features, and as soon as I purchase it, they will come out with the better-featured one. My life. Trying to wait for that because they make valid points on heat dissipation and wanting a cut-off switch. I am nowhere near as smart as people on this forum, so those things are not something I could take care of by myself (yet)

 

[BentleyJ]

I believe we can find comprssion pin lugs to reduce from 4AWG to 6. Give me a few minutes.

https://www.gordonelectricsupply.com/p/Burndy-Yev4Cp6X75Fx-6Awg-Adapter/6954437?gclid=Cj0KCQjwiIOmBhDjARIsAP6YhSUb8eNuJjIxuMDkYlG-BK1Gc1ADcFCTNKqTQp5VCeKD34gresXaKUcaAqBPEALw_wcB

Here is the part at Gordon Electric. Would shop around for a lower price.

 

[SniperX]

100A or 125A subpanels are relatively low cost. I would look at getting another subpanel, 20 space, without a main breaker at all. These are called main lug panels. Then you can install a standard 2 pole 80A breaker, back-feed that from the transfer switch and install all the other branch breakers for your existing loads and probably have a couple spare breaker slots. EDIT: This eliminates the Fuse/Breaker issues asked about above.

I am sort of following you here. This was what I was trying to figure out last night when I could not sleep. I do know the difference between a main breaker panel and a main lug panel. What I don't understand is what you mean by "backfeed". I am a real newbie. Does this mean, the main breaker panel has the 100A main plug and is wired to the middle part of my transfer switch. Do I take all the breakers out of this panel and put into the new main lug panel along with the new 80A double pole breaker that the Growatt 12kw wires to? Does it matter that 80A is more than half of 100A or 125A if I got a 125A panel? Could I just get a new 125A 20 slot main panel and add the 80A double pole breaker to that or is this where that 50% breaker rule comes into play? Not to exceed 50% of the total A of the main breaker? Hate to ask, but a diagram would make my brain happy. hand drawn is fine.

 

[SniperX]

https://www.gordonelectricsupply.com/p/Burndy-Yev4Cp6X75Fx-6Awg-Adapter/6954437?gclid=Cj0KCQjwiIOmBhDjARIsAP6YhSUb8eNuJjIxuMDkYlG-BK1Gc1ADcFCTNKqTQp5VCeKD34gresXaKUcaAqBPEALw_wcB

Here is the part at Gordon Electric. Would shop around for a lower price.

So this is like a reducer ferrule? I mean, not sure that is a term but basically a 4AWG wire goes into the barrel, you crimp and the end part is reduced to 6AWG? That is so the 6AWG part can fit in the screw connection but it is really still 4AWG so it can take the 140A? BRILLIANT if I am understanding this correctly.

 

[BentleyJ]

I am sort of following you here. This was what I was trying to figure out last night when I could not sleep. I do know the difference between a main breaker panel and a main lug panel. What I don't understand is what you mean by "backfeed". I am a real newbie. Does this mean, the main breaker panel has the 100A main plug and is wired to the middle part of my transfer switch. Do I take all the breakers out of this panel and put into the new main lug panel along with the new 80A double pole breaker that the Growatt 12kw wires to? Does it matter that 80A is more than half of 100A or 125A if I got a 125A panel? Could I just get a new 125A 20 slot main panel and add the 80A double pole breaker to that or is this where that 50% breaker rule comes into play? Not to exceed 50% of the total A of the main breaker? Hate to ask, but a diagram would make my brain happy. hand drawn is fine.

If you purchase a new 20 space, 100A or 125A main lug subpanel of the same brand as existing you could take all the breakers out and put them in the new panel. Then you just add a 2 pole, 80A and connect the middle of the transfer switch to the 80A breaker. It essentially becomes the main breaker which is the input connection for the power source which is either the Growatt or the Gen.
Not sure what you mean by the 50% rule but would not apply here in this configuration.

 

[SniperX]

So this is like a reducer ferrule? I mean, not sure that is a term but basically a 4AWG wire goes into the barrel, you crimp and the end part is reduced to 6AWG? That is so the 6AWG part can fit in the screw connection but it is really still 4AWG so it can take the 140A? BRILLIANT if I am understanding this correctly.

https://www.gordonelectricsupply.com/p/Burndy-Yev4Cp6X75Fx-6Awg-Adapter/6954437?gclid=Cj0KCQjwiIOmBhDjARIsAP6YhSUb8eNuJjIxuMDkYlG-BK1Gc1ADcFCTNKqTQp5VCeKD34gresXaKUcaAqBPEALw_wcB

Here is the part at Gordon Electric. Would shop around for a lower price.

So would I need 5 of these? I think these are the best prices I could find but I don't know all the good electrical sites. I would want to use 4 AWG and utilize these but on the ground, I could use 6 AWG since I can size down one size. Is this correct? Here is a photo of the connections. If I don't hook the generator directly into the AC Input, then I would only need 3 correct?

 

[BentleyJ]

You should only need 3 regardless of the generator connection. The gen is only 7000W so 6 AWG or even 8AWG wire is fine since its only 30A.

We were discussing the 80A breaker and I kind of got fixated on that number without thinking about it. 12,000 Watts at 240V is only 50A. Where did the need for an 80A breaker come from? You could avoid all these wiring issues by using a 60A breaker with 6AWG wire.

 

[SniperX]

If you purchase a new 20 space, 100A or 125A main lug subpanel of the same brand as existing you could take all the breakers out and put them in the new panel. Then you just add a 2 pole, 80A and connect the middle of the transfer switch to the 80A breaker. It essentially becomes the main breaker which is the input connection for the power source which is either the Growatt or the Gen.
Not sure what you mean by the 50% rule but would not apply here in this configuration.

I re-drew my plan.
What would be the purpose of the main panel besides providing the only earth ground? Could I purchase the same brand panel in 125A or 100A MAIN breaker style with more spaces and just rewire everything from the old panel to the new main breaker panel then the 80A breaker could fit into the new panel because it has more space. Would this alleviate the need to have the subpanel? I would just call this 100A panel in the first set of pictures a loss and fit a bigger Main breaker panel in the same space and just wire into that. I would probably go ahead and get a 125A panel if I can find it but with 20 spaces and just rewire that for a main panel. Buy the 80A double pole breaker and insert it and wire to the growatt 12kw.

 

[SniperX]

You should only need 3 regardless of the generator connection. The gen is only 7000W so 6 AWG or even 8AWG wire is fine since its only 30A.

We were discussing the 80A breaker and I kind of got fixated on that number without thinking about it. 12,000 Watts at 240V is only 50A. Where did the need for an 80A breaker come from? You could avoid all these wiring issues by using a 60A breaker with 6AWG wire.

The manual recommends an 80A breaker for the 12kw and 6AWG wire. I watched a video where Will said if you were above 10,500 plus continuous watts he recommends 4AWG. I figured I might as well just wire 4AWG and be safe. He was talking about the EG4 6500's in parallel. I am not sure if Growatt reprinted their manuals because I swear at one point it was a 60A breaker and that 6AWG would make sense but everywhere I look it says 80A now.

 

[SniperX]

The manual recommends an 80A breaker for the 12kw and 6AWG wire. I watched a video where Will said if you were around 10,000 plus continuous watts he recommends 4AWG. I figured I might as well just wire 4AWG and be safe. He was talking about the EG4 6500's in parallel. I am not sure if Growatt reprinted their manuals because I swear at one point it was a 60A breaker and that 6AWG would make sense but everywhere I look it says 80A now.

At 6:32 mark is where Will talks about the wire gauge. I figured this was 13kw total so somewhat comparable to my 12kw... I get into trouble trying to compare but I thought he had a valid point. I have 6AWG THHN wire rated for 90C and that is good for 75A so maybe it will work?

 

[SniperX]

I just want to tell you I really appreciate your time. I can't tell you thank you enough.

 

[Hedges]

I have a 100A main panel for the solar shed. All loads are on this but the panel is full and cannot take another breaker.

Tandem breakers