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Critique my setup

8-ball

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Feb 27, 2022
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Ok so I watched a bunch of will’s videos and I’m basically trying to mimick what he did with his setup for mine. (See pic1 ). So I have 2 5K growatt inverters and a EG4 battery rack with 2 xEG4 100ah 48v batteries. It’s a 48v system with 20 x 460w panels. I am building the inverter wall now based on how I saw Will build his. I am missing one more PV disconnect switch in the pic it’s on the way. So I will have one for each inverter so I can have my strings to each inverter with the ability to turn off each array. I plan on adding 4 more 100 ah EG4 batteries to the battery rack once I can afford them 1-3 months.
Now for my questions.
I added busbars like Will did but I honestly have no clue what their purpose is? I added 2 150A fuse blocks on both positive battery cables, that was the biggest fuse I could find. Is that big enough? I will have 2awg battery cable from the battery rack to the bus bar but from the bus bar to the fuse and fuse to inverter is it ok to drop to 4awg? Keep in mind I will eventually have 6 batteries. I plan on doing batteries in parallel. The only reason for the drop in wire size is I can’t seem to source the cable locally. Signature solar sent me 2 awg with the rack and batteries but I needed a bit more and 4awg was the best I could find. Total cable length from batteries to the inverter is no more than 6-7 ft. Do you see any major mistakes? Second pic is what I am trying to copy with Wills system.

List of parts






Thank you
 

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The systems we make are like ladders, the busbars are the risers and the circuits are the rungs.
Lets start with the math.
5000 ac watts / .85 conversion factor / 48 volts low cutoff = 122.549019608 inverter amps
122.549019608 inverter amps * 2 inverters = 245.098039216 service amps
245.098039216 service amps / .8 fuse headroom = 306.37254902 fault amps.
You busbars should be rated for 300 amps but they are actually rated for 150 amps.
Since they are brass I'm not confident they are even good for 150 amps.

Your batteries are good for ~100 amps per and that is pushing it.

I'm trying not to overwhelm you here.

We have not talked about fuse or wire size.
If you indicate your interest we can do that in subsequent messages.

UPDATED: fixed math thinko
 
Last edited:
I guess you could stack the lugs on the busbar but that kind of defeats the point.
 
The systems we make are like ladders the busbars are the risers and the circuits are the rungs.
Lets start with the math.
5000 ac watts / .85 conversion factor / 48 volts low cutoff = 122.549019608 inverter amps
122.549019608 inverter amps * 2 inverters = 245.098039216 service amps
245.098039216 service amps / .8 fuse headroom = 306.37254902 fault amps.
You busbars should be rated for 300 amps but they are actually rated for 150 amps.
Since they are brass I'm not confident they are even good for 150 amps.

Your batteries are good for ~100 amps per and that is pushing it.

I'm trying not to overwhelm you here.

We have not talked about fuse or wire size.
If you indicate your interest we can do that in subsequent messages.

UPDATED: fixed math thinko
Thank you for your reply. So I don't have near what I need for fuse or busbar. Looking online I cant find any bus bars above 200A except one which is rated at 600A, but its expensive. Do I need a busbar? I found one T class fuse but its rated for 12-24V not 48V. If you happen to have time can you send me a link to one I can buy? If I increase my battery system to total of 6 will this change the fuse I need?

This is the one I found

Busbar I found
 
First things first.
Does your battery rack have integrated busbars?
 
First things first.
Does your battery rack have integrated busbars?
Yes it does. I have this one.

 
Yes it does. I have this one.

Cool.
Make sure to flip one of the busbars so that the main connection point is at opposite ends.
Positve on top and negative on bottom.
Connect each battery to the rack with 4 awg or better.
The batteries contain a breaker that EG4 stands behind so the batteries are sufficiently over current protected.

Now we have options for how to connect the AIOs.

We can...
1. Connect each inverter independently to the rack busbars each inverter circuit will have its own fuse.
Fuse size depends on wire size.

2. Connect a common feeder wire to the rack busbars and terminate that wire on the cheap busbars in the vicinity of your AIOs.
In this case we would use a thick wire for the feeder and a big fuse and then 2 thinner wires to the inverters each with their own smaller fuse.

I would need to see a picture of the aggregation point on the rack busbars to make a determination of which way to go.
 
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