diy solar

diy solar

Live Ground Shocked 5 Year Old

Quattrohead said:
If whoever we are talking about has the wrong size transformers for the inverters then I don't know why we're having this discussion.
European/rest of world growatt inverters and transformers have no place in the split phase world, it's inherently too dangerous to make work properly.
Click to expand...

Yes but ... Growatt now sells a "US" model 240V 60Hz inverter with N-G bonding screw removed, and an auto-transformer.
Not sure exactly what their UL listing says, but it isn't clear what wattage inverter the auto-transformer is supposed to be used with, or how to protect it.

SolarEdge and SMA also sell 240V inverters with separate auto-transformers. SMA used to sell a different auto-transformer to get 120/240V split-phase from 120V inverter. The SMA ones were packaged with transfer switch so auto-transformer was never paralleled with grid, and it was big enough for the inverter.

I suspect some UL Listings are more equal than others.
 
Quattrohead said:
European/rest of world growatt inverters and transformers have no place in the split phase world, it's inherently too dangerous to make work properly.
Click to expand...
Electricity itself is inherently dangerous, if you don't know what you are doing.
As far as single phase in a split-phase world. Every thing in this split-phase world originates from single phase, through a transformer.
 
timselectric said:
Absolutely
If the transformer is wired in series with the load. Like in this thread.
Maybe not if "T" tapped at the loads panel.
Click to expand...

If 25A 2-pole breaker feeds 240V L1/L2 of auto-transformer like I show in this thread, it allows 50A 120V 6000W load between N and L1 (or N and L2).
My measurement showed approximately 3.5A in each of L1 & L2, 7A in N, confirming this.

The Growatt transformer in question spec's only 3000W imbalance.

So I disagree 25A on L1/L2 provides protection.

Curious to see your current measurements again. I do recall they challenged my reasoning.
Please measure no-load current too. Maybe that transformer has high no-load current due to saturation. I'm running mine at 50% of rated voltage.
 
finite said:
Someone correct me if im wrong as ive no experience with growatt inverters or interconnecting them but from my knowledge this is how it should be wired in its current config id refer to @timselectric for proper bonding to earth. fuse as needed with your 2 growwatts feeding 1 2 pole breaker, then a single pole breaker feeding the auto transformer, autotransformer feeding the main lug of the right hand panel.
Click to expand...
That's fine,
Except that the grey wire in the drawing, between the inverters and transformer, should be black. So that it's not confused with a neutral. AND BE ON THE BREAKER, NOT THE NEUTRAL BAR.
 
Last edited:
It is my understanding(which could be wrong), inverters for the U.S market come split phase 120/240 wheres as his units only put out 240 hence the need for the auto transformer.
 
finite said:
It is my understanding(which could be wrong), inverters for the U.S market come split phase 120/240 wheres as his units only put out 240 hence the need for the auto transformer.
Click to expand...
They come in a few variations.
120v single phase
240v single phase
120v/240v split-phase

Plus a few 3-phase variations.
 
finite said:
It is my understanding(which could be wrong), inverters for the U.S market come split phase 120/240 wheres as his units only put out 240 hence the need for the auto transformer.
Click to expand...
Yes, and the auto transformer makes it so the wire color standards should use N. America wire colors... because that is the system he is using.
 
Supervstech said:
Yes, and the auto transformer makes it so the wire color standards should use N. America wire colors... because that is the system he is using.
Click to expand...
And after the auto transformer that is dictated, im sorry for the confusion white doesnt show up well on a white back ground. Ill be sure to not put so much effort into further posts to avoid such scrutinty over a drawing meant to assist the OP
 
finite said:
And after the auto transformer that is dictated, im sorry for the confusion white doesnt show up well on a white back ground. Ill be sure to not put so much effort into further posts to avoid such scrutinty over a drawing meant to assist the OP
Click to expand...
White or grey is acceptable for neutral.
It just can't be used for a line conductor.
 
finite said:
And after the auto transformer that is dictated, im sorry for the confusion white doesnt show up well on a white back ground. Ill be sure to not put so much effort into further posts to avoid such scrutinty over a drawing meant to assist the OP
Click to expand...
No good deed goes unpunished.

Illegitimi non carborundum

I used to have a T-shirt that read: does anal retentive have a hyphen?
 
finite said:
You are correct, and in that case i should have have blue and brown coming out of the growatts.
Click to expand...
Industry standard would be black and red.
For reference.
Up to 250v is L1-black, L2-red, L3-blue, N-white
250v to 600v is L1-brown, L2-orange, L3-yellow, N-grey
In both cases G-green or bare

There are other cases for a high leg or bonded leg delta system.
 
Im aware of american standards, im also aware all european fixtures and appliances i have installed have brown and blue leads.
Grounds may also have a yellow tracer
 
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