diy solar

diy solar

Opinion on stacking lug terminals on inverter post?

I avoid doubling up on wires because I was taught that even though the wires should have the same resistance, there’s instances they may not. This wold cause the amps to unevenly flow through the wire, perhaps melting one. This could get worst the more conductors that are put in Parallel.

This uneven resistance could be caused by uneven wire length or a bad crimp on one end in the lug where the wires are joined, or a couple other instances.

There’s also how to fuse that wire now. Whether the wire is fused after they are joined with 200 amps, or if each individual wire needs to be fused at 100 amps. Adding a fuse to each individual wire could cause these connections to have different internal resistance. I don’t have the equipment to measure resistances so small over the wires, fuses and connections,

My google searches never turned up industry standards on this. Just turned up YouTube videos, forum posts, Quora, and some articles, but no NEC standards.

I’ve had to double up a couple of times. My Overkill BMS was delivered with 2 AWG wires in each of the positive and negative sides, so I crimped those to a single 6 AWG lug to go on the busbar. My DC to DC converter would not fit the 12 volt ground and 24 volt ground with two lugs into the stud, so that got crimped in the same lug. On a short run once, I did double up with the wire with two gauges below what I wanted to use, but ran it through the voltage drop calculator in post #36.

I guess no doubling, got it.

I know I "should" get 4/0, but the project just didn't call for it and the price difference was unpleasant ($91 vs $158 for 10'). My intended goal is to average about 500 watts constant. This should easily work with a 1/0 wire (I thought it was overkill as is). I'm also going to keep my wire distances short...like 4 ft round-trip.

I think I'd rather move to a 24V system later to basically side-step this problem.
 
My intended goal is to average about 500 watts constant. This should easily work with a 1/0 wire
I thought about something like that. What stopped me is I'm not sure my family or friends would understand (or care) about those limits.

I started with 12 volts and moved up to 24 volts. Going to 24 volts was not one of the 3 phases of my initial build but was something I was considering. Big thing was an inverter swap, battery upgrade, more panels for more power, and switching to lithium for more useable storage.
 
I thought about something like that. What stopped me is I'm not sure my family or friends would understand (or care) about those limits.

I started with 12 volts and moved up to 24 volts. Going to 24 volts was not one of the 3 phases of my initial build but was something I was considering. Big thing was an inverter swap, battery upgrade, more panels for more power, and switching to lithium for more useable storage.
I control the circuit usage, so no one will be plugging into it.

Yeah, the inverter swap isn't fun. Already LiFePO4 and panel voltages will be high enough (total output is a different story!) Maybe I can sell the 12V inverter for 80% of its value. Maybe.
 
My inverter swap turned out to be not bad. I had a 12 volt 2000 watt SAMLEX and swapped it for a 24 volt 3000 watt SAMLEX. The spec sheet said the mounting screws were in a different location, but it was in the same area. I'd already had 4/0 wire, so attaching the DC wires was Easy.

The FLA to lithium battery swap and adding the AC/DC charger and adding the DC to DC converter took a bit more time.
 
My inverter swap turned out to be not bad. I had a 12 volt 2000 watt SAMLEX and swapped it for a 24 volt 3000 watt SAMLEX. The spec sheet said the mounting screws were in a different location, but it was in the same area. I'd already had 4/0 wire, so attaching the DC wires was Easy.

The FLA to lithium battery swap and adding the AC/DC charger and adding the DC to DC converter took a bit more time.

Sorry, I didn't word it well. The inverter swap itself is trivial, it's the sell/buy situation I'm disliking. :cry: Actually, I better check the size of the future inverter to ensure it fits on the board...
 
($91 vs $158 for 10').
Doesn’t that bite!
I just bought a couple short lengths of 2/0 to allow me to swap out ‘test’ inverters without removing the primary. Apparently I ordered the same thing a year or so ago ($24) but this time it was $57. No inflation there.
I think I'd rather move to a 24V system later to basically side-step this problem
By the time you ‘need’ 4/0 cables 12V probably has stopped making sense. While I can think of two situations where staying 12V with 3000W+ of needed power is required might be appropriate, those are highly improbable for most people including me.
I'd already had 4/0 wire, so attaching the DC wires was Easy.
And that is one of the two main reasons to overcable stuff!
 
I avoid doubling up on wires because I was taught that even though the wires should have the same resistance, there’s instances they may not. This wold cause the amps to unevenly flow through the wire, perhaps melting one. This could get worst the more conductors that are put in Parallel.

This uneven resistance could be caused by uneven wire length or a bad crimp on one end in the lug where the wires are joined, or a couple other instances.

There’s also how to fuse that wire now. Whether the wire is fused after they are joined with 200 amps, or if each individual wire needs to be fused at 100 amps. Adding a fuse to each individual wire could cause these connections to have different internal resistance. I don’t have the equipment to measure resistances so small over the wires, fuses and connections,

My google searches never turned up industry standards on this. Just turned up YouTube videos, forum posts, Quora, and some articles, but no NEC standards.

I’ve had to double up a couple of times. My Overkill BMS was delivered with 2 AWG wires in each of the positive and negative sides, so I crimped those to a single 6 AWG lug to go on the busbar. My DC to DC converter would not fit the 12 volt ground and 24 volt ground with two lugs into the stud, so that got crimped in the same lug. On a short run once, I did double up with the wire with two gauges below what I wanted to use, but ran it through the voltage drop calculator in post #36.
NEC 1/0 minimum conductor size for parallel conductors in a circuit. Circuit fuse for one conductor and not the sum of parallel conductors.
 
Use 2/0 marine grade or equivalent cable for the inverter.
 
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