Cable question

gcp · Apr 16, 2012

While cleaning part of my property yesterday, I found about 50 ft each of 4/0, 2/0, and 2 AWG wire. This wire is aluminum, and was used to provide AC power to a mobil home which was removed when I bought these particular 5 acres. I plan to use it where possible to connect my solar system's battery bank to my 5Kw inverter, it'll probably be a 20 foot run, but the only reservation I have is the aluminum material vs. the preferable copper. Your thoughts will be appreciated.

gcp · Apr 16, 2012

Well, it's better to be lucky than good, sometimes :thumbsup:

Today I came across and purchased from a local store three 12V AGM/sealed batteries for $50 each. The owner said he sold 40 more last Friday and these three were the last at hand. Too bad I didn't stop by his place on Thursday, I would have bought at least 5 more.

I guess my plans have now changed as I can install these batteries inside the house since they don't outgass. Which mean 2AWG wire can be used in such a short run since the batteries and the inverter will now be co-located. But I'll have to make longer wire runs from the solar panels to the batteries so I estimate that the 12AWG AC copper wire, I have a lot of at hand, ought to suffice for this 30 ft run.

Tractor Seabee · Apr 16, 2012

In your earlier posts you were talking about about a 5KW inverter. The inverter name plate may well say KVA rather than KW. KW is a little different depending on Power Factor which at unity is the same as the KVA. That requires a 60 A circuit on the 120 volt side unless you limit by circuit breaker the output amps. You will get an actual 41 Amps but need to upsize circuit per code if full capacity is planned. Something is not adding up on your battery cableing scheme. What is the input voltage requirement on the inverter? That will determine how you connect the solar cells and batteries (series/parallel) and the wire size to interconnect the cells and batteries. Another variable is the capacity of the battery charger. All components have to be matched. Distance is not your basic problem here it is the circuit ampacity on both sides of the inverter. You are talking a lot of batteries to get 5KW capacity on both sides for any significant time period with no or limited input as the solar panel output will vary from 0-full capacity. There are lots of manufacturers out there that provide free engineering if you ask, a lot of the info is available on line.

More info is needed to design this system.

Ron

yelbike · Apr 16, 2012

I'll have to make longer wire runs from the solar panels to the batteries so I estimate that the 12AWG AC copper wire, I have a lot of at hand, ought to suffice for this 30 ft run.[/QUOTE]

You need to find out how many panels your using, the current may be enough that even 10' can create a voltage drop. Depending on the voltages maybe able to use the 12 awg if you run two wires from each panel to charge controller. Remember lower voltages must br in much shorter distances.

gcp · Apr 16, 2012

Tractor Seabee, there's probably a lot in what I write that doesn't make sense, right now, because I am feeling my way through this project but when I'm done it will.....I hope :laughing:

My inverter is a Wagan 5,000 Watt AC Inverter that operates with an input voltage range of 10-15 VDC. It has four 120VAC outlets rated at 15amps each. To begin with this will be off the grid and will be used only when there's power loss. But if/when I build confidence in the system I'll start using it at night for TV, lights, security system, and such other lesser current draw appliances. Please understand, this is my weekend place so there are no washers/dryers and/or ovens to content with. There are a couple of window AC units but I plan to run those with grid AC. So, all that's left are lights and other such low wattage items to power for a couple of hours or so, at night. You are right, info is only one phone call away but isn't this acquisition process fun?

yelbike, I am using three harbor freight 45 watt panels which will give me a 135 total watts of charging capacity. Each came with its own controller but if I can connect all 3 panels into one controller that'll be preferable to me (less boxes to turn on and off) but 4 amps is the internal fuse of each controller so I don't know that I'll be able to get away with using just one. Let's keep this discussion going.