Solar wiring question

[Jonnygsx]

Looking to install solar on my prowler 24lz trailer. Watching and reading peoples installations it seems that the best thing is to install your charge controller near your battery and then wire directly to the battery. However on my trailer the best location for my panel is on the rear, so running wires all the way to the front where my batteries are will be a bit of a challenge. I did see a few instances where the controller was wired into the wiring for the converter. Is this an acceptable option? Will there be a greater volt loss by doing this method vs having the controller near the batteries with a short run of power wire to the batts?

[mena661]

BFL13 wrote:
The pigtails on my 230w panel are:

(UL)E310273 RHH OR RWH-2 / E305787 PV wire 12AWG 90C wet or dry 600v
Sun Res -40C >> H+S 12583780-766507 RADOX SMART << TUV.COM ID:
0811307400 PV1-F 4MM2 120C 0.6/1 KV

The strands are a shiny silver colour.

Nothing there denotes copper or aluminum but Southwire's aluminum RHH/RWH-2 90C wet or dry wire is rated to 2000V. Their copper RHH/RWH-2 is 600V. Probably just a difference in manufacturers ratings.

[BFL13]

Yes, I am not using the pigtails that came with the panel. The junction box seems to be sealed or I haven't figured out how to get it open, unlike the usual ones with screws for the cover, but if I can't bust in, I'll snip them off short as possible and wire on from there.

[Salvo]

My 140W panels from Solar Blvd had 16 awg pigtails. That 3 foot pigtail has twice the resistance than the total 8 awg cable length from panels to converter. The panels were cheap, but you get what you paid for. It's simple to open the cover of the panel junction box to remove that pigtail and replace it with better cable.

Sal

[BFL13]

The pigtails on my 230w panel are:

(UL)E310273 RHH OR RWH-2 / E305787 PV wire 12AWG 90C wet or dry 600v
Sun Res -40C >> H+S 12583780-766507 RADOX SMART << TUV.COM ID:
0811307400 PV1-F 4MM2 120C 0.6/1 KV

The strands are a shiny silver colour.

[mena661]

BFL13 wrote:
On that, when you buy the fancy 25 ft or whatever long MC4 cables to plug your fancy MC4 panel pigtails to, are they also aluminum? So what is their real AWG value? Phooey. I will stick to doing my own wiring; at least that way I know what is going on.

The one's I found on Ebay are copper.

30 ft #8 MC4

BFL13 wrote:

Is there a way to tell if they are cu or al with those MC4 cables without cutting them?

If there are wiring standards printed on the insulation, you might be able to tell from that. Take a pic of your wiring and post it here.

[BFL13]

Yes that warning came from the manual for an ASC controller I had which was a shunt type.

I did have some problems with some wiring schemes I was trying out with my series type PWM where I had some converter going through the controller because I got things mixed up. It just didn't work. Speculation was because that particular controller was meant to be positive grounded if the installation required it to be grounded.

Once I got things all the right way around with controller and converter in parallel it was fine.
----------

Is there a way to tell if they are cu or al with those MC4 cables without cutting them?

I have been looking at Home Depot's well pump wire which is amazingly low cost. You get four wires twisted together with each wire being stranded copper #12. I am thinking you could parallel two each for pos and neg and get a set of #9s in effect, which would be good with the long 24v run from array to controller. Haven't decided yet

[JiminDenver]

BFL13 wrote:
My new 230w panel with the fancy MC4 3ft long wires as pigtails, turned out to be those wires are 12 AWG aluminum, not copper, when I snipped them off shorter.

So not too impressed with that. I like the other panels I have/had with a junction box and terminals in it that you attached your own wires. Then you knew what you were getting.

On that, when you buy the fancy 25 ft or whatever long MC4 cables to plug your fancy MC4 panel pigtails to, are they also aluminum? So what is their real AWG value? Phooey. I will stick to doing my own wiring; at least that way I know what is going on.

I use a set of those fancy MC4 cables and it llooks like I'll be getting another set too. Mine are solid copper strands.

[DryCamper11]

BFL13 wrote:
No, I meant ...Don't short your converter.

Ah! I see what you were recommending. You were referring to the difference between a shunt regulator and a series regulator. The former short circuits the current source and the latter open circuits it.

You are right, of course, but I assumed he wasn't asking about that issue. I thought he was asking about using the cables from the output of the converter to make connection to the batteries (to avoid running a new set in parallel).

[BFL13]

As the OP knows, for short lengths you don't need to worry so much about al vs cu for AWG value, so not worth hacking off wires to see what they are unless it is critical.

In my case it was necessary to use fatter wire without the MC4s, panel to controller, so I snipped the pigtails in order to join them to the fatter wire and saw that the pigtails were aluminum. Was not impressed.

Then I see they sell long lengths of wires with MC4s on them so you can just plug everything in easy-peasy. Hmmmmm, I say. 😞

[Jonnygsx]

BFL13 wrote:
My new 230w panel with the fancy MC4 3ft long wires as pigtails, turned out to be those wires are 12 AWG aluminum, not copper, when I snipped them off shorter.

So not too impressed with that. I like the other panels I have/had with a junction box and terminals in it that you attached your own wires. Then you knew what you were getting.

On that, when you buy the fancy 25 ft or whatever long MC4 cables to plug your fancy MC4 panel pigtails to, are they also aluminum? So what is their real AWG value? Phooey. I will stick to doing my own wiring; at least that way I know what is going on.

Hrm these are good things to know. I just picked up my MC4 cable and it is 10gauge. But i didnt look to see if it was aluminum I assumed copper. I haven't received my panel yet, should be here monday. Now im interested to see what the pig tails on it are.

Yes this whole battery location vs solar location and how to connect the two is giving me a headache. One thing is that I haven't actually mounted my new GC2 batteries yet. So i have had the option to consider wiring them to the back bumper. As another poster mentioned AGM woulda been brilliant because I could have put them under the kitchen seats. But with these flooded cells they have to go either on the back or on the front. It seems that the front is the most likely choice. I am a bit concerned with tongue weight as my trailer is right on the edge for my vehicle. But I am only towing it 10miles or so from its storage location to where ill be using it. Im not planning to haul this across the country so it should be ok.

[BFL13]

My new 230w panel with the fancy MC4 3ft long wires as pigtails, turned out to be those wires are 12 AWG aluminum, not copper, when I snipped them off shorter.

So not too impressed with that. I like the other panels I have/had with a junction box and terminals in it that you attached your own wires. Then you knew what you were getting.

On that, when you buy the fancy 25 ft or whatever long MC4 cables to plug your fancy MC4 panel pigtails to, are they also aluminum? So what is their real AWG value? Phooey. I will stick to doing my own wiring; at least that way I know what is going on.

[Salvo]

I just installed 2 140W panels from Solar Blvd on my son-in-law's TH TT. I ended up removing the 4 feet long MC4 cables attached to the panels. Those cables had extremely thin wires. I used 8 awg cables for connections down to the controller.

One of the most difficult decisions is where to drop the cable through the roof. When possible, I want to avoid putting extra holes in the roof.

My first choice is the fridge vent. That didn't work because this TT did not have an intake side vent, rather the intake was through the floor.

My second choice is to go through the black tank vent. That didn't work because the vent is only 1/2" ID. The cable didn't fit.

The last choice is to drill a hole right below junction box. The best location to drop the cable was a dead zone area, right in the front of the TT. The cable is hidden from view, and it's now a short run from charge controller to batteries.

Something for the OP to think about.

BTW, regarding OP's question. The converter cable may have a long run and be higher resistance than you would want. That means solar charge will not be as efficient.

Sal

[ewarnerusa]

Jonnygsx wrote:

...Initially Im only going to be running one 120watt evergreen but I would like to wire suitable for at least 3 panels.

The wiring plan I am beginning to settle on was a junction box on the roof with a 10guage to 6 or 4 guage terminal. Running that through the roof of the bedroom at the front of the trailer and then going to the controller on the backside of the front wall of the trailer. Then going 4 gauge to the batteries which would be less than 5 feet away.

How much space do I need around the controller, is it like a converter where it can get very hot? My trailer has a cover over the propane tanks on the front but it isnt very protected. I would guess its better to have the controller inside the trailer than under this cover outside?

Your initial plan is very similar to the way I approached it. I initially planned to install one 140 watt panel but wanted room to grow without having to rewire if/when I did. Seems like MC4 connectors only go down to 12 gauge so that is what I used for panels to a junction box on the roof. Then 4 gauge from the junction box to the controller (about 15' of wire length) and 4 gauge from the controller to the batteries with about 5' of wire length. I went with a Morningstar Tristar 45 PWM controller and I really like it. Its terminals can handle up to 4 gauge and it uses temperature compensation. I ended up starting with 2 x 140 watt panels due to sale price and I have not added any more. So my wiring and controller are quite a bit oversized for my current needs, but I have the capacity to expand. The same panels have gone on sale again a few times since then and I've been very tempted to expand just because I could, but I put the money into new batteries instead which I think was the right choice. You need a nice reservoir to store the power in before going wild on the harvesting capacity.

Regarding your original question for the thread, it is best to put the controller as close as possible to the batteries due to voltage drop. So if you can't get close, compensate with oversized wires. My dad's TT, which is our old TT that I mentioned in one of your other threads, had it's controller output tied into the converter output wires. I'm pretty sure the original owners had the solar installed by the dealer when new and they did it as quickly and easily as possible. I watched a demo video of dealer installers putting in solar and that is exactly how they did it. This is not ideal due to long wire length and associated voltage drop. From what I gather, and from what is in my and my dad's TT, the wiring from the converter to the battery isn't even sufficient to let the converter work optimally. For one 120 watt panel it is probably OK, but since you're planning for expansion I would suggest using wire you know is fat enough.

[BFL13]

Jonnygsx wrote:

BFL13 wrote:
No, I meant do not run a charger through the controller. Go past the controller somewhere toward the battery.

Other charging sources besides a solar panel can damage the controller or the other source itself because the controller regulates by shorting its input. (at least some controllers do, if not all types.) You can short a panel, no harm. Don't short your converter.

I was only asking if I could use the wires that run from the converter to the batteries. I wasn't going to run any pre-regulated power through another converter/controller. That would be stupid.

Well, I almost did it that way so I thought I'd mention it. I was behind the barn when they were handing out brains though. 🙂