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Safe Grid Use of the 5000ES and transformer

This is good thinking.

Also a good idea.

Excellent

What you have drawn is fine.
And, it will evolve like everything else.
I know that what I currently have, is not what I originally designed. And, will probably not be the final system.
Thanks, I'll proceed... looks like 2 smaller panels is about the same as one larger. And I already have the transfer switches. But I may swing loads slowly until I understand. The panels are to go onto a barn that doesn't exist yet... So I'll get the panels in place, maybe try driving it from the batteries.
 
Greetings,

Based on all the help I have received thus far, here is a diagram of my plans for review. I'm using the US version and the autotransformer. Since White wires don't show up on white background, all Neutral wires are shown in blue. Questions, comments? Thanks!

GroWatt auto-transformer with breakers - if that disconnects, does it shut off your "House Critical" panel?
Or does it supply 240V to L1 and L2, but leave neutral floating?
 
GroWatt auto-transformer with breakers - if that disconnects, does it shut off your "House Critical" panel?
Or does it supply 240V to L1 and L2, but leave neutral floating?
Greetings,
between the Inverter and the transformer there is a 2P 20A, to protect the transformer. From the transformer to the transfer switches there is an over/under breaker. Its 3P, if L1 or L2 to N drops/raises over 10% normal it will trip taking L1, L2 and N offline. For any reason L1-N is not providing 120v to the transfer switch and the grid is suppling power to the switch, it will shift the load to the grid by switching L1, L2 & N. There are 3 transfer switches , house critical, house, non-crictical, and barns. The switches can be placed in manual mode allowing either source to be picked. That should allow balancing house loads to expected battery SoC or inverter load. As for the barn, 95% of the time its light use, but then there are times when a welder and/or motors might be in use, so switch to grid for those peak loads. The goal of the project is; 1) 100% up time for freezers, lights, furnace is case of grid outage. 2) reduce grid usage such the payback is under 10 years ( I estimate 6). 3) Hedge against raising energy costs. Hope this helps, let me know if I have not explained it or if you see issues! Thanks!
 
Greetings,
between the Inverter and the transformer there is a 2P 20A, to protect the transformer. From the transformer to the transfer switches there is an over/under breaker. Its 3P, if L1 or L2 to N drops/raises over 10% normal it will trip taking L1, L2 and N offline. For any reason L1-N is not providing 120v to the transfer switch and the grid is suppling power to the switch, it will shift the load to the grid by switching L1, L2 & N. There are 3 transfer switches , house critical, house, non-crictical, and barns. The switches can be placed in manual mode allowing either source to be picked. That should allow balancing house loads to expected battery SoC or inverter load. As for the barn, 95% of the time its light use, but then there are times when a welder and/or motors might be in use, so switch to grid for those peak loads. The goal of the project is; 1) 100% up time for freezers, lights, furnace is case of grid outage. 2) reduce grid usage such the payback is under 10 years ( I estimate 6). 3) Hedge against raising energy costs. Hope this helps, let me know if I have not explained it or if you see issues! Thanks!
Can you draw that out on paper and upload a photo? I am also interested in how you are grounding this system as Signature Solar is yet to provide a grounding solution that does not use multiple grounds.
 
Mro Supply sales isolation Transformer 5 KVA part # C1F005LES for $523 free shipping why are we entertaining using midpoint Transformers when looking to use the grid as backup with all of these hassles for only $150 cheaper?
 
Once this is figured out with the midpoint on us version the options are unlimited. That can be easily mounted stacked and are reliable.
 
New to the forums and trying to wrap my head around everything, Bud Martin got me over to this thread and I’ve been trying to do a lot research to make my set up safe. I have the ES-5000 US model which I am told is not ground and neutral bonded, but the ground for AC in and out are bonded.
My set up after having it mis configured for 120v instead of 240 thanks to Bud is fixed. I have the ground wire connected in the main panel and L1, L2 and G going to the inverter. I have a EG lipo4 battery connected to the battery terminals and no PV currently. When the inverter is on I can see the 240v out and each leg is 120. Now with having L1 and L2 and ground, you don’t have a neutral. I want to have a sub panel per day. Which is where Bud Martin was saying to use the Auto Transformer to give me the neutral.

How are you suppose to have a ground for the transformer. NEC talks about the only spot your suppose to ground neutral and ground is at the main panel. Your not suppose to have separate rods due to a possible loop issue. I’ve been reading here about how how the auto transformer can try to compensate for the grid transformer if connected. I’ve tried to find video tutorials, but almost all of them are fully off grid or don’t show their ac setup. I feel like I’m at a loss and going in circles. Sorry for a long post, been trying to make this system as safe as possible and doing a lot of reading
 
New to the forums and trying to wrap my head around everything, Bud Martin got me over to this thread and I’ve been trying to do a lot research to make my set up safe. I have the ES-5000 US model which I am told is not ground and neutral bonded, but the ground for AC in and out are bonded.
My set up after having it mis configured for 120v instead of 240 thanks to Bud is fixed. I have the ground wire connected in the main panel and L1, L2 and G going to the inverter. I have a EG lipo4 battery connected to the battery terminals and no PV currently. When the inverter is on I can see the 240v out and each leg is 120. Now with having L1 and L2 and ground, you don’t have a neutral. I want to have a sub panel per day. Which is where Bud Martin was saying to use the Auto Transformer to give me the neutral.

How are you suppose to have a ground for the transformer. NEC talks about the only spot your suppose to ground neutral and ground is at the main panel. Your not suppose to have separate rods due to a possible loop issue. I’ve been reading here about how how the auto transformer can try to compensate for the grid transformer if connected. I’ve tried to find video tutorials, but almost all of them are fully off grid or don’t show their ac setup. I feel like I’m at a loss and going in circles. Sorry for a long post, been trying to make this system as safe as possible and doing a lot of reading
There's not a simple answer.
If you have read this thread, you can see why.
If you want to use an autotransformer and connect to the grid. You will have to give up some of the safety.
 
There's not a simple answer.
If you have read this thread, you can see why.
If you want to use an autotransformer and connect to the grid. You will have to give up some of the safety.
Guess I am keeping the US one, which with no real flat out safe option. Which is the safest? The transformer to the grid. Is there any way to minimize the risk or have a fail safe if the grid option goes bad?
I saw Will said he uses battery chargers at certain times. Is there a way to use do it that way with the chargers and just say screw ac input? But that still leaves the question on the grounding of the system, per NEC it’s all suppose to go back where then the neutral is tied back to the grid and ground bars
 
Guess I am keeping the US one, which with no real flat out safe option. Which is the safest? The transformer to the grid. Is there any way to minimize the risk or have a fail safe if the grid option goes bad?
I saw Will said he uses battery chargers at certain times. Is there a way to use do it that way with the chargers and just say screw ac input? But that still leaves the question on the grounding of the system, per NEC it’s all suppose to go back where then the neutral is tied back to the grid and ground bars
If you don't connect to the grid. The inverter is a new power source. And the new loads panel is now a main panel. N/G bond is done there.
 
If you don't connect to the grid. The inverter is a new power source. And the new loads panel is now a main panel. N/G bond is done there.

Then....
You can either, connect to the existing grounding system. Or stay separated from it, and drive a separate ground rod.
 
Then....
You can either, connect to the existing grounding system. Or stay separated from it, and drive a separate ground rod.
Is there a good charger to buy? I saw SS had an 48v / 18 amp. Would that keep things charged all the time if I ran off the battery by itself, or do I need a bigger one? I am planning on around 3k-3500 watts continuous on the system out of the 5k
 
I think an isolation transformer can make a safe implementation.
After the transformer, you have 120/240V split-phase and you tie the center tap to ground from main panel.
 
FYI: link to afmiller thread.

BTW: I am surprised that with all the threads about the 5000ES US safety issue, the user manual and the AC input output terminals are still not corrected with correct labels and instructions by Signature Solar.
 
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I think an isolation transformer can make a safe implementation.
After the transformer, you have 120/240V split-phase and you tie the center tap to ground from main panel.
Yes, I believe that this is the best option. If wanting to connect to the grid.
 
btw you have a misunderstanding here across the threads about the European grid topology.


If you have an inverter with a bond between its GND and "neutral" output, then it is actually a PEN output, NOT N! It should not be labeled as GND,N,L - instead it should be labeled as GND,PEN,L. You cant hook PEN into one of the inputs of an autotransformer to make 240/120 split phase, where the center N of the split phase output is grounded! Common misunderstanding.

Reference: https://www.normadoc.com/english/din-vde-0100-540-vde-0100-540-2012-06.html

If your EU model inverter has a GND bond then it is designed as replacement of the utility power, so it has to be hooked into the house connection point, same way as the utility grid is (and not just somewhere in the house, like an input of an autotransformer).

Another misunderstanding: autotransformer is not same thing as isolation transformer with two 120V windings in series. On the autotransformer you can potentially get the whole 240V power input out of one of the 120V legs, while isolation transformer will be designed in a way to allow to draw only half of the 240V power from each of the 120V legs.

Same holds for the popular split phase inverters like 6kw MPP, you will not get 6kW from one of the 120 legs! You can rather imagine these units as two 3kW / 120V inverters working in series. Each subunit will give only 3kW on each 120 leg. So autotransformer solution is clearly superior and cheaper than split phase inverters, but certainly poses some security risks.
 
btw you have a misunderstanding here across the threads about the European grid topology.


If you have an inverter with a bond between its GND and "neutral" output, then it is actually a PEN output, NOT N! It should not be labeled as GND,N,L - instead it should be labeled as GND,PEN,L. You cant hook PEN into one of the inputs of an autotransformer to make 240/120 split phase, where the center N of the split phase output is grounded! Common misunderstanding.

Reference: https://www.normadoc.com/english/din-vde-0100-540-vde-0100-540-2012-06.html

If your EU model inverter has a GND bond then it is designed as replacement of the utility power, so it has to be hooked into the house connection point, same way as the utility grid is (and not just somewhere in the house, like an input of an autotransformer).

Another misunderstanding: autotransformer is not same thing as isolation transformer with two 120V windings in series. On the autotransformer you can potentially get the whole 240V power input out of one of the 120V legs, while isolation transformer will be designed in a way to allow to draw only half of the 240V power from each of the 120V legs.

Same holds for the popular split phase inverters like 6kw MPP, you will not get 6kW from one of the 120 legs! You can rather imagine these units as two 3kW / 120V inverters working in series. Each subunit will give only 3kW on each 120 leg. So autotransformer solution is clearly superior and cheaper than split phase inverters, but certainly poses some security risks.
You can't use the European version in the US, without modification. (Removal of the bonding screw)

Growatt labeled the inverter. We have begged them to change it.

An autotransformer is a single winding, with a center tap. It doesn't create two 120v legs. It creates a midpoint that is halfway between the the two ends. Which can be used as a neutral, for 120v.
It's exactly the same as the output side of an isolation transformer.
The difference between an autotransformer and an isolation transformer is the second winding in the isolation transformer. Which electrically isolates the input from the output.
Both types of transformers cause the same issue from a lost neutral/center tap. (A voltage imbalance)

Split-phase inverters are configured in different ways.
Some are two 120v inverters in one case. (Usually high frequency models)
some are 240v inverters, with a built-in transformer. (Usually low frequency models)
If the built-in transformer is an autotransformer. The full rated output can be drawn from either 240v or 120v.
 
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