Safe Grid Use of the 5000ES and transformer

[ArkRob]

I can tell you this isn't true. I personally was in the back testing dozens of these units under a number of different conditions to come up with a solution. As far as the picture, it was on a to-do list a mile long and honestly I am a one man guy trying to answer tons of requests in here. I promise I got it as soon as I had 10 seconds to take them, upload them, and post. Sorry about the delay, that is 100% my fault.

Edit: Just wanted to say that even though some might look at this as bad PR, I hope everyone can appreciate how transparent we have been on this issue and I do want to say that I've worked my tail off trying to answer hundreds of messages, phone calls, and emails, all while testing dozens of scenarios, drilling a hole in the wall of our workshop and pounding pipes into the ground. I really do my best and hope to continue having positive interactions with you all, on here and anywhere else, even in the face of hurdles like this week.

I do appreciate what you are doing, and understand that you have more to do than post here.

Can we see some uses with the grid passing through? I'd really like to see PV and grid and the effect they have on the loads.

If you will show us 120 loads with PV and grid input with no current trying to return to the grid, then I think we're running out of problems to discuss.

 

[Bud Martin]

SS: I just watch David video:
@16:18 I can see only one AC input breaker which is fine if you are feeding L, N, and Ground (as labeled on the terminals since this is US version is the modified ES version with new PCB that does not have N and Ground bonding), in this case with single breaker on L1 and no breaker on N (L2), if there is short circuit between L2 and case, it will depend on the house breaker to trip instead of the internal breaker (if they install one). Can you read the spec of that circuit breaker? May be GroWatt gets away with it since this model is not UL certified, so they do not install dual ganged breaker.
I would expect the device that is fed by L1/L2 will require to have dual breaker, that is what I have to use on the US 240VAC products to meet UL requirement.

 

[Solar Guy Richard]

I do appreciate what you are doing, and understand that you have more to do than post here.

Can we see some uses with the grid passing through? I'd really like to see PV and grid and the effect they have on the loads.

If you will show us 120 loads with PV and grid input with no current trying to return to the grid, then I think we're running out of problems to discuss.

Yes sir, we are reconfiguring the system and will have more, (hopefully less noisy), videos coming out shortly.

 

[Zwy]

Well...the point in the video I referenced @13:41 he is checking 1 of the 120 lines on a 2pole breaker while his 3pole breaker that he chose to protect the feed the of the auto transformer and its neutral open. If you go back another 30 seconds you'll get better context. He turned on the dryer and turned off the 3pole breaker protecting the transformer. Then with the dryer running he verified 0 volts on the 2 pole breaker he used as a test point and when he checked 1 phase to ground his meter showed 2.38 volts. He was expecting 0 volts and called it 0 volts but the meter read 2.38 volts. Now, 2.38 volts isn't nothing and it is real and draining to ground. Could you recreate this scenario with an ammeter inline so we know how much 2.38 volts affect efficiency? Thanks.

I saw it when I first viewed the video and wondered where the stray voltage is coming from. I decided to think about it for spell, you know how the mind works. Granted, if there was a load on a circuit with 2.38V present open circuit, it would probably drop to 0.0V. I would have like to see if there is trace current.

I first thought it was from the breaker but I went back and looked, the voltage is from the neutral bar. From what I can see, the EGC runs from GW inverter to the breaker box. Is is bonded to the neutral was my next question? At 13:30, I stopped the video and you can see we have a grounding bus bar on the left and a neutral busbar on the right. The only thing on the neutral busbar is 2 wires. One is from the auto transformer, after the breaker.

I'm not certain where the stray voltage is from. It could very well be the 3 pole breaker. Or backfeed from somewhere else. I don't see a N-G bond in the breaker box.

I wouldn't jump to the conclusion it is the GW or autotransformer BTW, it most likely is in his wiring.

 

[Zwy]

Themselves and Poz have now shifted to talking about Off Grid use only. Your still going to have potential issues if you try to feed in the Grid.

Yes, grid backup would be an issue.

I wouldn't see a problem off grid with an isolation transformer, many of us are in agreement on that.

Your statement above is logical. I can see no reason that they would endure 10 days of bad PR on what was behind the grounding screw unless it was because they needed an answer from China and had to wait. I could have ripped one down for them in an hour and sent them the pictures.

 

[OpenNRG]

I do appreciate what you are doing, and understand that you have more to do than post here.

Can we see some uses with the grid passing through? I'd really like to see PV and grid and the effect they have on the loads.

If you will show us 120 loads with PV and grid input with no current trying to return to the grid, then I think we're running out of problems to discuss.

Here's a quick video showing grid pass through. I call it Grid Sharing.

 

[OpenNRG]

Another Happy 5000US customer.

 

[Zwy]

SS: I just watch David video:
@16:18 I can see only one AC input breaker which is fine if you are feeding L, N, and Ground (as labeled on the terminals since this is US version is the modified ES version with new PCB that does not have N and Ground bonding), in this case with single breaker on L1 and no breaker on N (L2), if there is short circuit between L2 and case, it will depend on the house breaker to trip instead of the internal breaker (if they install one). Can you read the spec of that circuit breaker? May be GroWatt gets away with it since this model is not UL certified, so they do not install dual gang breaker.
I would expect the device that is fed by L1/L2 will require to have dual breaker, that is what I have to use on the US 240VAC products to meet UL requirement.

Good eye, there is the double pole breaker which he replaced earlier in the video. Obviously an editing error.

 

[Zwy]

Here's a quick video showing grid pass through. I call it Grid Sharing.

Nice, single pole breakers in that breaker panel. I want to see him flip one on. Only one.........

 

[Bud Martin]

Good eye, there is the double pole breaker which he replaced earlier in the video. Obviously an editing error.

I am talking about the internal circuit beaker inside the unit @16:18 in the video, it should be dual gang breaker not single breaker to protect L1, the breaker is locate at the bottom left of the unit in the video.

 

[Zwy]

Another Happy 5000US customer.

Nice lockdown kit on the backfed breaker.......

 

[Zwy]

I am talking about the internal circuit beaker inside the unit @16:18 in the video, it should be dual gang breaker not single breaker to protect L1, the breaker is locate at the bottom left of the unit in the video.

The factory one, yes, I see now.

 

[Mr-Sandman]

It would take a lot to read and follow all this thread.

To SUM it up from MY understanding.

1. You need to make sure the ground is NOT bonded inside the Growatt 5000ES inverters. This is the grounding screw issue. If purchased from Signature Solar you should be good to go, anywhere else, all bets are off. Buyer Beware.

2. These inverters are generally used with an Autotransformer which adds some additional safety concerns. If the autotransformer fails, overloads, or is disconnected while power is still being supplied by inverter(s), 240v will be applied to one leg of your 120v circuits, potentially frying a lot of stuff. The fix to this is make sure power is disconnected if autotransformer is ever disconnected or fails. There is more than one way to fix this, but generally you need a breaker setup that disconnects the loads or inverters output if the Autotransformer is ever disconnected from the panel or tripped.

3. Grid Pass Thru with autotransformer Re-circulating current. This is an issue that doesn't have a good solution with the Signature Solar or Solar Edge autotransformers. The issue is the autotransformer is going to try to balance the utility grid loads all the way to the utility transformer "not just inverter loads" when the inverter is in grid pass thru mode. The worst part of this is, it's going to try to do it though the bonded shared ground, since the Growatt 5000ES does NOT pass neutral thru the inverter.

I still stand by my statement: I do NOT recommend this setup for Grid connected installations. Offgrid can be made safe IF the installer knows what they are doing.

 

[Clifton]

Here's a quick video showing grid pass through. I call it Grid Sharing.

This is with a 240v load only though

 

[Mr-Sandman]

This is with a 240v load only though

Ya I was going to say, I didn't even see any autotransformer in use.

 

[axle-b]

Ya I was going to say, I didn't even see any autotransformer in use.

and batteries

 

[fafrd]

It would take a lot to read and follow all this thread.

To SUM it up from MY understanding.

1. You need to make sure the ground is NOT bonded inside the Growatt 5000ES inverters. This is the grounding screw issue. If purchased from Signature Solar you should be good to go, anywhere else, all bets are off. Buyer Beware.

2. These inverters are generally used with an Autotransformer which adds some additional safety concerns. If the autotransformer fails, overloads, or is disconnected while power is still being supplied by inverter(s), 240v will be applied to one leg of your 120v circuits, potentially frying a lot of stuff. The fix to this is make sure power is disconnected if autotransformer is ever disconnected or fails. There is more than one way to fix this, but generally you need a breaker setup that disconnects the loads or inverters output if the Autotransformer is ever disconnected from the panel or tripped.

3. Grid Pass Thru with autotransformer Re-circulating current. This is an issue that doesn't have a good solution with the Signature Solar or Solar Edge autotransformers. The issue is the autotransformer is going to try to balance the utility grid loads all the way to the utility transformer "not just inverter loads" when the inverter is in grid pass thru mode. The worst part of this is, it's going to try to do it though the bonded shared ground, since the Growatt 5000ES does NOT pass neutral thru the inverter.

Good summary and my understanding as well.

I still stand by my statement: I do NOT recommend this setup for Grid connected installations. Offgrid can be made safe IF the installer knows what they are doing.

I’m also uncomfortable with the single-phase-240VAC-grid-toed-with-Autotransformer architecture to offset consumption because of unease about the idea of an Autotransformer balancing non-critical loads in parallel with the transformer on the utility pole (using Growatt’s architecture or any of the number of similar approaches by other vendors.

Is there a recommended architecture considered ‘best’ for this use-case?

A pair of grid-toed 120VAC inverters seems like it may be a better approach to grid-tied consumption offset - is there anyone making such a solution that will push power to the grid using an energy meter or CT sensors?

Backup power is a different animal and not a priority for me - I’m just looking for a cost-effective solution to capture solar power into a battery and offset consumption both during the day as well as after the sun has gone down…

 

[Mr-Sandman]

Is there a recommended architecture considered ‘best’ for this use-case?

Yes, there's several. My opinion if you are going to be grid interactive, you should look at UL certified/listed equipment.

I personally use a Schneider XW Pro 6848, it is completely grid interactive. You can set it up to self consumption, sell to grid, grid backup, load shaving, time of use, AC Coupling with grid/battery, and more. It's a 240/120 split phase unit "NO autotransformers needed", has Neutral pass thru and built in transfer switches.

I'm sure there's some cheaper china options, but I will not comment on those, since I have no personal experience with them.

 

[OpenNRG]

You people are unbelievable. ArkRob asked to see a video of Grid Pass through. Whether it has an auto transformer or batteries is pointless. Doesn't matter to you. You're going to find something to bitch about. Here's a couple of more. I doubt these will make you happy either. This why I don't participate more. All the bullshit coming from the no-it-alls.

Here you go. Nit pick these!!!!!

 

[Bud Martin]

I have these units, and have installed these units from SS. Nice unit, works great, no issues. These were received last year, 2021, in Nov.
Yes, the Labeling is incorrect on the Nameplate and the N labeled connections, but SS clearly states that N is L when purchasing. Yes, the labeling does need to be changed, as, everyone is confused and there is no way to tell the difference between a ES and US unit, as they are are labeled ES.
Attached are pictures of the unit showing the N and G are not tied. Pictures also show the PCB has been modified as SS claims, as the ground screw people remove on other sellers units is still in place and grounded. This means that the Neutral trace has been changed to floating line on the PCB(I haven't looked any farther at this point, just wanted to put this put there to satisfy curious minds)

Can you read the spec of that AC input thermal circuit breaker for L (L1) on the bottom left of the unit? Thanks.