AlaskanNoob
Solar Enthusiast
- Joined
- Feb 20, 2021
- Messages
- 915
Alright, maybe a 48V bus bar shouldn't kill me, but it's not out of the realm of possibility that I'd try wiring a solar string directly to it...
Anyway, I'm trying to finalize the cable lengths for the Quattro and MPPT connecting to the bus bar before I put in the order. I set my Quattro 4" from the MPPT to comply with the spacing distances (we will have an identical second MPPT but we're not installing it yet because our custom solar ground mounts broke our bank and so we're only putting in two strings this summer, hence only wiring in a single MPPT for right now).
Positive bus bar with two large T-fuse holders, and two smaller T-fuse holders. The two smaller holders in the center will go to the MPPT (two positive cables going to two positive connections). The two larger holders on the outside will go to the Quattro. All 8 remaining unoccupied positive studs will go to 8 Pylontech US5000 batteries.
Three questions for the generous out there:
A) I measure my positive cable length as 18" for the two Quattro positive cables, and 19" for the two MPPT positive cables. Should I go with those numbers to keep it as short as possible, or round it up to 24" to give me some wiggle room? I could also move the bus bars closer to the devices and shorten the lengths if needed a bit.
B) How far away should my negative bus bar on the bottom be away from the positive bus bar, or does it matter? I know I want to keep it relatively close so that my negative cables won't be too much longer than their positive cable counterparts, but I'm under the impression that I don't want to make it easy to drag my keys or something across both at the same time (they have covers, so I imagine that should make it not a big deal how close they are).
C) These little plastic tabs on the cover for the t-fuse holder will get in the way of the cables. I assume I just cut those tabs off as required?
I was thinking about building a wall where the Quattro is recessed into the wall, so that its DC terminal line up on the same plane as the bus bar and the MPPT. That would allow for shorter cables and no bend.
But I think for now I'm just gonna slap it all up on the wall to start. Unless somebody tells me that 2 foot cables is not keeping it short enough. I'm using two sets of 4/0 for the Quattro, and 2 sets of 4/0 for the MPPT, so I think I've got plenty of copper to keep the resistance pretty low *I think*.
Many thanks for the words of wisdom. I'll standby to learn I bought the wrong bus bars for some reason...
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