Cabin prep for future PV array, is this correct cable to put through wall?

oldmancharlie

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Aug 21, 2021
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Hello,

This winter I will use a Bluetti AC200P, charging periodically with gas generator.

Next spring I will ground mount 700W-1400W of panels (exact size/how/why TBD).

I need to seal up the cabin for this winter though, and want to put a cable through the wall that will easily plug into the PV array outside and the Bluetti, but later a charge controller, on the inside.

Is this cable at my shortest useable length the way to go?


Thanks!
 

MichaelK

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Mar 21, 2020
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I would say no, that's a poor choice. It's only 10 gauge. Here's a wire chart that can help you make the correct choices. A common strategy is to run individual solar strings into what's called a combiner box, and then from the combiner box to the charge controller. The combiner holds individual circuit breakers, and each string gets it's own breaker. All the amps then get combined in the downstream section of the combiner that goes to the controller. So, the wire choice is going to be governed by the number of amps you are running through each string, and the total number of strings.

In my own case, I have six strings that are about 8A each, which totals up to be around 48A. I used 4 gauge wire from the combiner to the controller because the 70A limit gives me a wide safety margin.

In reality, 10 gauge might be OK for a starter system with only 700W, but if you chose to expand in a year or three, you won't have to rip out thinner wire and replace it. I'd rather overbuild at the start then worry about capacity years down the road.
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oldmancharlie

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Aug 21, 2021
Messages
11
We're in a starter cabin on a property and by the time the PV system expands substantially we'll be in a different house, so I'm not too worried about redoing with larger wires as it will all be moving anyway. My priority is to make it easiest to plug and play next year. It's actually probably easier to think about this system as a stand alone system that I will end up using elsewhere. The maximum I will do to expand is double it's battery capacity and add an array reasonable for the unit and my latitude.

I didn't know about the combiner box, that sounds like a good idea. I was going to put in-line fuses on each panel?

But back to this 'plug and play' which is getting harder... I will have to go from two wires with MC4 connectors to an MC4 to XT90 adapter to charge my Bluetti AC200P. I found this one:

dodgy amazon MC4 to XT90

and one from Bluetti, but I can't find it on amazon or their Canadian or American website

Bluetti MC4 to XT90

They are also 10AWG, so the same issue if I go bigger... Can I source these connectors and then wire them with larger/better wire? Or am I just getting into trouble trying to do more with this Bluetti than I should?

Or actually, can I just run bare wires of good quality and larger size, and put an XT90 adapter on the end? Is there any downside other than cost for going bigger? (I don't know electricity good).

Thanks!
 

MichaelK

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Mar 21, 2020
Messages
1,484
When you lead the wire to the charge controller, you must cut the head off anyway to fit into the controller terminal, so I wouldn't spend extra money on cables already terminated with connectors. Just go to HomeDepot, and buy a measured length of substantial wire, and put the correct terminal on one end.
 
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