Safety hazard w/ Growatt 5000ES (European version) when connected to American grid

Will Prowse

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If you're using a growatt 5000es (European model that I don't use in my videos) with an auto transformer, you need to watch this video. The output of the inverter bonds the ground and neutral, which is designed for use with European grid. Conversely, American grid uses center tap transformer to designate ground/neutral. This creates a massive safety hazard. You will have 120V on ground of the inverter, and this can kill you if you complete circuit to earth ground when input is connected to American grid. Or if there is a bypass situation, you will have a dead short and it will overload the inverter.

I know people are using these units to save money, but it's a bad idea. Also, the actual output of these transformers is pretty low. You are better off using a inverter that is designed for use with American grid.
 

FilterGuy

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Thank you for alerting us to this @Will Prowse

There are several fundamental problems around grounding on DIY projects.

1) Many of the inverter manufacturers do not provide adequate documentation on how the inverters deal with grounding. Growatt and MPP are among the worst at this (I have often said that it borders on criminal negligence on the part of the manufacturers).
2) There is a *lot* of misinformation on the web about grounding. (Thankfully, I have not seen too much of it here on this forum)
3) Grounding is far more complex than most people realize and far too many people do not understand grounding. Worse yet, many people that think they understand it, don't.
4) It is easy to build something that appears to work fine but is fundamentally unsafe because of the way the grounding and bonding are done on the project.

Add to that the use of products designed for one country being used in another country and it is a huge problem.
 

Struc

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I'm not saying I know anything about anything, but I just pulled my Growatt SPF5000ES out of the box, and I have NO connectivity between ground and the marked Neutral (L2 for our use), either input or output.

I have a somewhat hard time believing that, if it were true, that nobody would have caught onto it by now, or even found out by accident.

How can you have a dead short between L2 and ground, and these things aren't blowing up all over the place everywhere?
 
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Bud Martin

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May be it is activated when it is in inverter mode or it can be turned on/off in the settings?
 

Will Prowse

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I'm not saying I know anything about anything, but I just pulled my Growatt SPF5000ES out of the box, and I have NO connectivity between ground and the marked Neutral (L2 for our use), either input or output.

I have a somewhat hard time believing that, if it were true, that nobody would have caught onto it by now, or even found out by accident.
It has to. It's designed for European grid. Sounds like you have a defective unit.
 
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Hedges

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The output of the inverter bonds the ground and neutral, which is designed for use with European grid. Conversely, American grid uses center tap transformer to designate ground/neutral. This creates a massive safety hazard. You will have 120V on ground of the inverter, and this can kill you if you complete circuit to earth ground when input is connected to American grid.

An isolation transformer could work.
Or a transformer with 3, 120V windings in series, rather than the usual 2, 120V windings of most auto-transformers.

If such an inverter has grid input, same issue there, and probably only isolates "line" with a relay, not "neutral" which would get driven by a center-tapped autotransformer on secondary. That is a hazard for linemen, backfeeding into grid.
Would need a second transformer on primary side.

Whenever someone here tries to use a 220V single-phase European model for US split-phase I worry about that.

It has to. It's designed for European grid. Sounds like you have a defective unit.

Slightly different model number. Is it grid-connected? In which case, would pass through grounded neutral from house, if grounded there.
 

Will Prowse

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Just talked to signature solar and their 5000ES has the ground neutral bond removed in every unit. This must be what you're referring to @Struc
 

Bud Martin

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Just talked to signature solar and their 5000ES has the ground neutral bond removed in every unit. This must be what you're referring to @Struc
Did they just remove the screw as shown on the video only? for true safety, they need to install insulator (that has high Voltage break down) between the chassis and the PCB where ground point is since the gap between the PCB and the chassis is very very small as mention on the video, some flexing on the PCB can easily make contact with the chassis.
 
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Bud Martin

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If Signature did remove the Ground bonding then they MUST indicate that with the sticker on the unit and in the user manual saying that it is modified unit, if some one bought another one from another vendor, I.E. Watts247, and try to use it, they will have a big surprise.
 

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Even it’s removed I wonder how inefficient it is if you use the grid tied into it? Probably explains why Poz keeps his grid connection separate.
 

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If you're using a growatt 5000es (European model that I don't use in my videos) with an auto transformer, you need to watch this video. The output of the inverter bonds the ground and neutral, which is designed for use with European grid. Conversely, American grid uses center tap transformer to designate ground/neutral. This creates a massive safety hazard. You will have 120V on ground of the inverter, and this can kill you if you complete circuit to earth ground when input is connected to American grid. Or if there is a bypass situation, you will have a dead short and it will overload the inverter.

I know people are using these units to save money, but it's a bad idea. Also, the actual output of these transformers is pretty low. You are better off using a inverter that is designed for use with American grid.
Saw Ian's video last night and would have posted it myself if you hadn't. So many issues with using one of these and the dangers of possible electrocution. I've been trying to tell people there are much better choices out there, all on deaf ears because some companies push these and some Youtuber's have videos promoting this unit.
 

Zwy

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If Signature did remove the Ground bonding then they MUST indicate that with the sticker on the unit and in the user manual saying that it is modified unit, if some one bought another one from another vendor, I.E. Watts247, and try to use it, they will have a big surprise.
Sig Solar might be out of business after someone dies needlessly. Modifying the unit by removing the N-G bond is just a lawsuit waiting to happen.

The biggest issue with removing the N-G bond is the case of the unit will no longer be grounded. Touch the case and you're grounded, you're most likely dead.
 

Quattrohead

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Saw Ian's video last night and would have posted it myself if you hadn't. So many issues with using one of these and the dangers of possible electrocution. I've been trying to tell people there are much better choices out there, all on deaf ears because some companies push these and some Youtuber's have videos promoting this unit.
I am joining the "me too" crowd. I have been banging on about this cheap hack since day one on here and asked SS about their new transformer the other day. Their reply was rubbish or a misunderstanding. Finally a proper discussion about this issue.
 

Struc

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Just talked to signature solar and their 5000ES has the ground neutral bond removed in every unit. This must be what you're referring to @Struc

I think it is most likely that due to their relationship with Growatt that they receive them that way. I find it hard to believe that Signature Solar would be opening every one of these to modify. Same thing for Watts247. I'll be interested to what they have to say, however.

Somebody recently floated the notion around that there was a SPF5000US (instead of ES) model. Although it's not printed on the label, maybe that is the difference. Could just be a designation of one with the Neutral/Ground connection removed.
 

Hedges

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The biggest issue with removing the N-G bond is the case of the unit will no longer be grounded. Touch the case and you're grounded, you're most likely dead.

N-G bond wouldn't be what grounds the case. It grounds the neutral (assuming case is grounded). Case needs a separate ground wire.
 

Hedges

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Just talked to signature solar and their 5000ES has the ground neutral bond removed in every unit. This must be what you're referring to @Struc

Absolutely. I'll ask them on phone tomorrow.

Or maybe they will see this post @SignatureSolarUS

I see a problem, a safety hazard. The Devil is in the details.

Is there a schematic showing how to connect grid and transformer?
"Line" input to "Line1" from grid, "Neutral" input to "Line2" from grid?

Manual says,
"...and a UPS function module in one machine, which is perfect for off grid backup power and self-consumption applications."
"Solar and utility grid can power loads at the same time"

I think this means it can pass grid AC input to loads through a relay, and when grid is down opens the relay (likely SPST isolating line only, not neutral), then drives 240Vrms AC on output Line relative to Neutral (which designers thought was ground.)

With output Line and Neutral connected to an auto-transformer having center tap grounded, Line is 120Vrms and "Neutral" is driven to 120Vrms (180 degrees out of phase for 240V total).

If only Line not Neutral is isolated by relay, so utility Line1 isolated but Line2 not, this would drive 120Vrms back into Line2.
It would not be apparent when tested by disconnecting both Line1 and Line2 with a 2-pole breaker. But during a power failure, there would be serious problems.

 

Quattrohead

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AC power is a very complicated subject, connecting some random stuff up and throwing a switch "oh look it works chuckle chuckle" is easy to do.
Making it safe for IF a fault occurs is the devil in the details.
That is why I had to change my post the other day on Poz coz I called him a rude thing.
 

robby

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I keep saying it, there is no way a Growatt with a transformer is going to pass an electrical inspection unless your lucky enough that your cousin is the inspector. Then your second issue is always going to be an electrical fire breaking out. Once the fire dept traces the fire source back to the inverter your insurance company has a free get out of payment Pass.
BTW Growatt UL Certified!
I just do not believe it.
 
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