Installing Cabling For Solar

Grandad5 · Senior Member

Installing Cabling For Solar

valiant81 · Guru

Hi Grandad5;

As for joining the cable from your solar panel (s) most of the panels that i have fitted have had a juction box on the back of the panel so easy to do the connection there , be very carefull of the polarity!!!. what i did when i fitted the panels to my caravan ( I have a 2012 jayco pop top ) was to wire and fit the panels to the top of the roof of my caravan and useing about 3 mtr of heavy 12 Volt cale was able to have enough cale to run to the solar controler and that was fitted to the inside of clothes cuboard.

I then ran a second cable from the solar controler to the house battery, fused with a 40 Amp fuse close to the positive terminal of the batter. Finaly a third cable ( Load ) and down to the main fuse pannel for all of the 12 Volt curcuts.

If you have to join low voltage cable what i do is stip the insulation, twist and then solder the connection and finaly re insulate the connection with 2 layers of heat shrink insulation. Never had a problen.

Dougwe · Chief one feather

How,

Jim, I used 6B&S cable all the way from the panel to the charger and don't get any current loss at all. I also have a portable 120w panel that was wired the same and again works great, it's out doing it's thing as we speak. And will have fully charged the battery by about 1.00pm VIC time.

Some people told me it was all over kill but I reckon when it comes to 12v and Solar Power there is no such thing. IMO.

Not sure if I am any help but just what I did.

Dougwe · Chief one feather

Sorry forgot to say, any joins were with Anderson plugs and they are at the outside end anyway.

Grandad5 · Senior Member

valiant81 wrote:
If you have to join low voltage cable what i do is strip the insulation, twist and then solder the connection and finaly re insulate the connection with 2 layers of heat shrink insulation. Never had a problen.

I can do that. Should have already realized it myself. Soldering has to be best way if I go that route.

May I ask what size cable you used for how many watts of solar at what voltage?

I've been advised that 6AWG is the ideal for every 300W of solar @ 12V but that this size (13mm sq) is awkward to physically attach to the panels

Therefore I plan to use 8AWG (6mm sq) @ 24V

How does this compare with what is actually working for you?

Jim

Grandad5 · Senior Member

Dougwe wrote:
Jim, I used 6B&S cable all the way from the panel to the charger and don't get any current loss at all.

Current Loss!!! That was what I was trying to retrieve from memory!

See my comment above. How did you go physically handling 6AWG at the panel? I was told it was near on impractical to use.

Jim

SnowT · Guru

Hey Jim.. I don't know your exact situation..

but with my system..

I ran a set of 35mm Cables thru the Bus to a Large format J-Box and from there I ran a set of 6mm2 Cable to each set of cable's.. There are 4 sets of Cables all joined together in the J-box..
>> I used Double insulated Welding Cable... far cheaper than Going to an Auto Electric Shop...

I did the wiring this way due to the fact that The Longest run of Cable would of been over 10m and I want to reduce the Maximum Cable run of any one cable to a minimum.. I could of changed how I ran the Cables but I had a need to have more than just the Solar going thru the roof.. -- My system at the moment is running at 20A @ 24v [1200w @ solar] -

So for your situation, depending on the number of solar panels you plan to have and the longest cable length that you have...

If you are planing for a Free camping setup.. then as a minimum then make sure you have as much solar as you can put on the roof as Possible..
-- If you can run a set Cable at least 10-16mm2,[sorry I'm an Electrician Not an Auto Elect] then connect all the Solar Panels to them...

Juergen

valiant81 · Guru

Hi all & grandad5;

I've used the same a doughwe 6b&s size and off the top of my head i think it's rated at 30 odd Amps, also IF your cable is copper, no need for a soldering iron, I just use a small pencel gas flame to heat the area and aply the solder to the joint in question.

As for the connections to the panel , not a problem, the juction box at the back of the panel has solder terminals for the wireing. I have two 120 Watt panels on the roof and one of the panels has two cables to each of the teminals, still had plenty of room in the gland for larger cable, if needed.

On a nother note, Voltage drop can play a big part in your instalation, so some times it is better to uses larger cable than what would be required. Haveing said that most of the installs that i have come across uses 6b&s size. Easy to use, cheap, and double insulated.

One final thing, were to install the solar controler. Try and keep it as close as practical to your house battery, but you still must be able to see/ read the display. Remember Voltage drop is your enemy !!!

-- Edited by valiant81 on Tuesday 14th of October 2014 03:56:35 PM

-- Edited by valiant81 on Tuesday 14th of October 2014 03:57:30 PM

oldbobsbus · Guru

6 B&S for me too I used MC4 connectors and used the original leads on the panels and then extended to the controller..

I don't really know if I have any voltage drop but I do know I am harvesting as much power as I need.. smile

Treecrest14 · Senior Member

Just a suggestion - run the cables up to the overhead cupboard and then when you decide to install the panels, have your Regulator in the cupboard where the wires come out of the side wall!! Thereby you have it out of the way, but accessible .

Grandad5 · Senior Member

thank you for your input everyone.
I'll let you know how I got on.

Cheers
Jim

wasn_me · Guru

This chart might be of use. It's the simplest one I've found especially the wire size cross reference.

Cheers Pete

mr glassies · Guru

I'm coming on the right through the roof into the microbe wave cabinet through the fridge cavity through the floor across to the left of the van and up into the cavity under the seat as thats were my batteries are .
and putting the controls behind the lounge in the corner .

waits hahahah.

dibs

-- Edited by mr glassies on Saturday 18th of October 2014 05:23:43 PM

Grandad5 · Senior Member

Oh I can relate to your install dibs. That's exactly the scenario I'm trying to avoid. It's a lot of work rebuilding a van from the ground up. There HAS to be some advantages. This is one of them.

Pete, thanks heaps for that link. I was just about to get out the calculator and brush up on my algebra theory when I found a link at the bottom to an online converter.
Too easy.

I figured 400 watt maximum. More likely 300 with flexibles, at 24V gives me 16.7Amps.

On the calculator I entered in 2 mtr run, (actual will be about 6ft or 1.8 mtrs) and bumped the wire temp up to 35C instead of the default 25C and it tells me 10B&S is enough.
So my 8B&S should be ample with room to move.

Dontcha love it when a plan comes together?

Jim

-- Edited by Grandad5 on Saturday 18th of October 2014 05:56:37 PM