Safe Grid Use of the 5000ES and transformer

[HighTechLab]

Full stop - Big issue here.

Adding a second grounding electrode for the separately derived system, not bonded to the buildings ground system and calling it good is not acceptable.

Per 2020 NEC 250.50 all grounding electrodes at a building or structure shall be bonded together.

This code language very specifically says, they "SHALL be bonded".



Also, a big issue is that if the autotransformer breaker trips, neutral is gone and all devices are fried. If you have a 100a service feeding the transfer switch, then to the critical loads panel, it is trivial to have over 25a of neutral current. This is why NEC defines the size and ampacity of the neutral conductors and in this system, the neutral should have the same ampacity as the ungrounded conductors, which means your autotransformer is too small.

 

[Baknblack]

If grid doesn't feed your inverters, that eliminates some problems. Auto-transformer will generate a neutral from a floating 240V inverter. You should be able to tie in to grid from rest of house. I think you can also use an interlocked generator breaker to backfeed house while main breaker disconnected from grid.
Question is, does it safely float? (reportedly the screw removal at factory floats it.)
But you need to make sure that if breaker feeding auto-transformer trips, L2 and L2 feeding the panel is also disconnected. Don't want 120V loads determining voltage of neutral. There are ways to do that.

Years ago I was back feeding during a power outage. I started turning on breakers and fried every piece of electronics in the house. I got to looking around afterwards and found the clamp had rusted off the ground rod at the meter. Expensive lesson.

 

[SignatureSolarJames]

@SS, Is this true?
POST #23: "That's what they told me today and they stated the Chassis do not need to be grounded."

Growatt SPF 5000 ES Wiring for 0 Export / Need help

I have my growatt 5000es setup like you describe. Check out my diagram I posted. I am trying to get it verified, so use at your own risk. Any questions on inverter settings, let me know. I can send you what mine is set to, and what settings do. This is how these units are to be set up, you can...

diysolarforum.com

Some one will get hurt.

see our diagram, this is not our position

 

[SignatureSolarJames]

Full stop - Big issue here.

Adding a second grounding electrode for the separately derived system, not bonded to the buildings ground system and calling it good is not acceptable.

Per 2020 NEC 250.50 all grounding electrodes at a building or structure shall be bonded together.

This code language very specifically says, they "SHALL be bonded".

View attachment 80649

Also, a big issue is that if the autotransformer breaker trips, neutral is gone and all devices are fried. If you have a 100a service feeding the transfer switch, then to the critical loads panel, it is trivial to have over 25a of neutral current. This is why NEC defines the size and ampacity of the neutral conductors and in this system, the neutral should have the same ampacity as the ungrounded conductors, which means your autotransformer is too small.

The off-grid system represents a separate system here, like a Generator and an off grid system.
All grounds are combined on each system

See the storedge guide here, maybe we can accept that they got permitting all over the USA

 

[robby]

Full stop - Big issue here.

Adding a second grounding electrode for the separately derived system, not bonded to the buildings ground system and calling it good is not acceptable.

Per 2020 NEC 250.50 all grounding electrodes at a building or structure shall be bonded together.

This code language very specifically says, they "SHALL be bonded".

---SNIP---

Also, a big issue is that if the autotransformer breaker trips, neutral is gone and all devices are fried. If you have a 100a service feeding the transfer switch, then to the critical loads panel, it is trivial to have over 25a of neutral current. This is why NEC defines the size and ampacity of the neutral conductors and in this system, the neutral should have the same ampacity as the ungrounded conductors, which means your autotransformer is too small.

This is what I have been saying from day one. Just one wire comes off and everything in your house goes up in smoke and probably creates a fire that burns down your house. Yet Signature Solar keeps trying to push this thread with the title that they have a "Safe Grid usage wiring method" When anyone that knows anything about electrical work knows that is not true.

 

[SignatureSolarJames]

---SNIP---

This is what I have been saying from day one. Just one wire comes off and everything in your house goes up in smoke and probably creates a fire that burns down your house. Yet Signature Solar keeps trying to push this thread with the title that they have a "Safe Grid usage wiring method" When anyone that knows anything about electrical work knows that is not true.

With all electrical you have an issue is "just one wire" comes off
the voltage we read in these simulations though is 90-130 split, close enough not to damage and weird enough to notice immediately. This is a simulation because we just don't have the real-life issues predicted here btw.
Maybe folks who have actually built a lot of these might know more than the armchairs.

 

[robby]

With all electrical you have an issue is "just one wire" comes off

Yes that's a major issue and I did not know about the other problems until Ian did his video.

the voltage we read in these simulations though is 90-130 split, close enough not to damage and weird enough to notice immediately. This is a simulation because we just don't have the real-life issues predicted here btw.
Maybe folks who have actually built a lot of these might know more than the armchairs.

And why do you expect people who bought the product to do the work. I see that you have a Lab bench at your facility and Inverters and Transformers everywhere. Why not do a video showing exactly what happens?

 

[Quattrohead]

It is an accepted fact in the electrical world that a knackered neutral is bad news for 120v items. It actually is a problem that cannot be fixed except with a good neutral in a mains fed home. You actually CAN PROTECT against it here with a transformer (either type) by using a circuit breaker on the output 240 of the inverter.
Again, the grounding issue is a DIFFERENT issue, but similar if you get my drift. Now we are talking about a potentially dangerous modification to an inverter.
But until someone looks at the PCB and understands it, we are pissing in the wind.

 

[eabyrd]

knackered

That's a new one... Technical term I take it?

 

[Zwy]

The off-grid system represents a separate system here, like a Generator and an off grid system.
All grounds are combined on each system

See the storedge guide here, maybe we can accept that they got permitting all over the USA


View attachment 80690

That diagram shows 1" conduit between the main panel and the StorEdge Inverter. Then 3/4" conduit from inverter to transformer. EMT is used or PVC with a GEC according to NEC. If FMT is used, it can't be over 6 ft in length, as noted in the Notes.

Want to try again?

 

[Hedges]

Maybe folks who have actually built a lot of these might know more than the armchairs.

I think you underestimate the experience, education, and licensing of various people here.


One thing I think you're going to have to comply with is:

"Per 2020 NEC 250.50 all grounding electrodes at a building or structure shall be bonded together."


The StorEdge schematic you pasted doesn't show grounds at all. Probably with the assumption that all metal boxes get grounded per code.
It shows auto-transformer connected to StorEdge, not the loads panel. We don't know what magic happens inside. It may be intelligently switching the centertap or other connections based on whether it is connected to grid or not.


You're going to need to find a way to make your design safe and code-compliant. There are ways for your design to accomplish that (except regarding UL listing, which requires, well, UL listing.)

 

[Solar Guy Richard]

Yes that's a major issue and I did not know about the other problems until Ian did his video.

And why do you expect people who bought the product to do the work. I see that you have a Lab bench at your facility and Inverters and Transformers everywhere. Why not do a video showing exactly what happens?

I can state that we are doing exactly this. In fact, we have modified our building in attempts to duplicate many of the issues pointed out over the last week and will be sharing our results. This includes intentionally shorting at multiple locations in the system, driving additional grounds to simulate possible grounds externally from the system in a normal house (such as gas or water pipes as mentioned before), and a number of other possibilities as we think of them on the fly. We are diligently working to ensure the safety of this system to match or exceed expected results. There is definitely going to be follow up - videos, diagrams, and more - to come in this regard. I'd like to stress again that I want to be safe just as much as anyone here, and I'm setting these systems up (in more configurations than you can imagine) on a daily basis.

 

[Solar Guy Richard]

It is an accepted fact in the electrical world that a knackered neutral is bad news for 120v items. It actually is a problem that cannot be fixed except with a good neutral in a mains fed home. You actually CAN PROTECT against it here with a transformer (either type) by using a circuit breaker on the output 240 of the inverter.
Again, the grounding issue is a DIFFERENT issue, but similar if you get my drift. Now we are talking about a potentially dangerous modification to an inverter.
But until someone looks at the PCB and understands it, we are pissing in the wind.

I love the term 'knackered neutral' - this should be a mainstream technical phrase from this point on ?
On a serious note, we are looking into multiple possible solutions. Your posts have been a tremendous help in coming up with situations we haven't thought of, so thanks for that.

 

[Bud Martin]

I can state that we are doing exactly this. In fact, we have modified our building in attempts to duplicate many of the issues pointed out over the last week and will be sharing our results. This includes intentionally shorting at multiple locations in the system, driving additional grounds to simulate possible grounds externally from the system in a normal house (such as gas or water pipes as mentioned before), and a number of other possibilities as we think of them on the fly. We are diligently working to ensure the safety of this system to match or exceed expected results. There is definitely going to be follow up - videos, diagrams, and more - to come in this regard. I'd like to stress again that I want to be safe just as much as anyone here, and I'm setting these systems up (in more configurations than you can imagine) on a daily basis.

What kind of shorts circuit are you going to do? L1, L2 shorted the grounded chassis (bonded and un-bonded between two ground rods)? Shorted to the un-grounded chassis? etc. Voltage reading and leakage current test between chassis and ground?
Are we still going to see the pictures of the PCB where the screw is removed, and pictures of the bottom side of the PCB? Pictures of the chassis so we can see if the standoff is removed or not?
BTW, live wire shorted to the chassis is one of the test I perform in the lab to verify that the breaker will trip and no wires will burn up, it is part of the UL test.

 

[Sky-HHI]

I went to SS web site and looked for the 48v SPF 5000 ES to look at the Spec Sheet and when it went to where the spec sheet should display a message is displayed that says, NO PREVIEW AVAILALBE, FILE IS IN OWNER'S TRASH. Why are they hiding the spec sheet now??

 

[SolarPrep]

I've been following this from a distance since Poz's first video with the auto transformer and the lack of neutral protection. After watching the submissions, retractions, alterations, and general confusion I can only assume my initial assessment was correct.

There really is no safe way to integrate these units into a household that is going to use grid supplied power in conjunction with the inverter's output, and there is no way safely use the autotransformer unless you segregate all of your 120 volt loads into a separate panel fed by that beast.

eabyrd:

It seems you are correct. I don't see why there is so much resistance to the idea of a separate loads panel. They are easy to buy, install, etc. But the bigger issue is that this industry (like many others) is relying on influencers to promote their product, and sell them. Those people are being paid in many ways, such as free samples, discounts, affiliate fees based on links, etc.

No one has any means to verify what the background is of the person contributing. Many just follow online advice blindly, and the results may or may not be positive. It may not even be remotely legal. There are a lot of very intelligent, well-meaning people who contribute comments too. How does an average person decide how to proceed?

To my way of thinking, this is on the manufacturers. Why doesn't (for example) Victron get their equipment UL certified. Or Growatt, who sells huge numbers of this equipment here in the US. The excuse that it tedious and expensive is crap. I spent my career going around the world installing equipment that had to be certified for use at its point of installation. Canada, Asia, US, wherever. It requires employees, training, expenses.

But instead, we are discussing modifying a non-certified Growatt, to install and use in the US, with an auto-transformer that might not be certified.

I guess you get what you pay for. Right? I'm still upset that the company who told me my Victron inverter was UL certified were wrong, and I can't send it back and apply the money towards an Outback, SMA, or some other unit that is certified for installation according to US codes. So I won't be buying a Growatt, or anything similar.

All that being said, the last post by Hedges where he comes up with the bath tub scenario...I can actually envision that happening.

 

[SolarPrep]

That's a new one... Technical term I take it?

Not at all new...great term, used for many years!

 

[SolarPrep]

I think you underestimate the experience, education, and licensing of various people here.


One thing I think you're going to have to comply with is:

"Per 2020 NEC 250.50 all grounding electrodes at a building or structure shall be bonded together."


The StorEdge schematic you pasted doesn't show grounds at all. Probably with the assumption that all metal boxes get grounded per code.
It shows auto-transformer connected to StorEdge, not the loads panel. We don't know what magic happens inside. It may be intelligently switching the centertap or other connections based on whether it is connected to grid or not.


You're going to need to find a way to make your design safe and code-compliant. There are ways for your design to accomplish that (except regarding UL listing, which requires, well, UL listing.)

Hedges and High Tech Lab: Now you have done it...brought up the 2020 code. I've tried to do that recently regarding getting equipment installed an approved by my AHJ, and all I got was a bunch of unrelated comments and arguments from people who don't seem to grasp the implications. I won't do it again. I think instead I'll just sell off stuff I cannot legally install, and commit to a vendor and equipment that is certified, and call it good. So, Hedges, right now I'm thinking about ordering the SMA Sunny Boy for the grid tied portion, and worry about some off-grid stuff later. Probably Sunny Island, or Radian.

 

[Hedges]

So, Hedges, right now I'm thinking about ordering the SMA Sunny Boy for the grid tied portion, and worry about some off-grid stuff later. Probably Sunny Island, or Radian.

Sunny Boy/Sunny Island is a great system.
It has high starting surge for motors, and AC coupling is particularly good for AC loads during the day (e.g. running air conditioner)
Component ratings were optimized for European market, where one 6kW SI and two 6kW SB would work well backfeeding grid.
Here in the US, two 6kW SI and two 6kW SB for on grid, but if strictly off-grid it could handle four 6kW SB. The extra two could be used in a grid-backup system if manually (slowly) switched from direct grid tie to output of Sunny Island.

For now, it is the Sunny Island 6048-US model offered here. That is to be installed indoors (because front panel has openings), and I don't think there are features for peak shaving or backfeeding grid from battery with power stored from earlier.
I would imagine that the European models like 8.0 come to the US eventually, probably have those features and UL-1741-SA listing as well as being sealed for outdoor use.

Plan and price out whatever system you imagine installing eventually (including battery). There are various limits on wattage of inverter, battery charging, pass-through from grid. Depending on the price-point and performance you want, a hybrid of a different brand might fit better.

 

[HighTechLab]

Hedges and High Tech Lab: Now you have done it...brought up the 2020 code. I've tried to do that recently regarding getting equipment installed an approved by my AHJ, and all I got was a bunch of unrelated comments and arguments from people who don't seem to grasp the implications. I won't do it again. I think instead I'll just sell off stuff I cannot legally install, and commit to a vendor and equipment that is certified, and call it good. So, Hedges, right now I'm thinking about ordering the SMA Sunny Boy for the grid tied portion, and worry about some off-grid stuff later. Probably Sunny Island, or Radian.

Code is written in blood and fires. Shortcuts get people killed. You are smart to sell the stuff that you can't use properly, because that mature standpoint could be saving your life.

I'm a Sol-Ark fanboy. They have a real neutral. I was also looking into the MPP Solar 65?48?, the yellow one that Will just reviewed with the split phase output. My only complaint is that I really dislike how small the wiring compartment is, and I'm not sure if it can do peak shaving or a TOU schedule like the Sol-Ark can.