130w SP - 105ah AGM ?

[T1 Terry]

Hi.

Lance - you may find it worthwhile to set up a 10 meter long cable for your folding panel, and fit it with Anderson plugs. Using this will allow you to park in the shade, and collect some amps as soon as the sun's up. I recommend 4mm2 twin core cable,to ensure you have no voltage drop.

Hi Shonky, agree with the cable size for the 90w portable. 4mmsq is roughly the infamous 6mm auto cable conductor size roughly equivalent to 11AWG. 90w is about the limit for this size cable over that length though, run through this calculator the 130w panel also mentioned charging a 12v battery would result in http://www.calculator.net/voltage-drop- ... &x=25&y=12
Where 8AWG cable would halve that to
http://www.calculator.net/voltage-drop- ... &x=47&y=15.
Anything more than a 150w of portable panels requires 6 B&S cable at roughly 13.5mm sq conductor but anything heavier than that gets a bit hard to roll up and put away.
So as you suggest, 6mm auto cable is nice and light and relatively cheap, but really the 90w panel you have would be its limit, so best to be sure you won't later want to increase the portable solar capacity, if you are unsure, bite the bullet and use 8B&S or 6 B&S cable to be sure to get the full benefit.

T1 Terry

[shonky]

Hi, all.

T.I.Terry - re solar cable. I was assisting in shifting solar arrays consisting of eight 190w panels in series recently, on the grid but don't tell anyone, and noted they were all equipped with MC4 connectors which I understand are 2.5mm2, and the 6 meter long cable leads were 4mm2. Was this good practice?

[Lance]

Hi.

Lance - you may find it worthwhile to set up a 10 meter long cable for your folding panel, and fit it with Anderson plugs. Using this will allow you to park in the shade, and collect some amps as soon as the sun's up. I recommend 4mm2 twin core cable,to ensure you have no voltage drop.

Yep, I've done that in the past with 6B&S on a 50w portable and it's been effective.
That 50w is generally in the Teardrop though and I don't like moving them about too much 'cos I'll end up leaving home without it at some stage.

[T1 Terry]

Hi, all.

T.I.Terry - re solar cable. I was assisting in shifting solar arrays consisting of eight 190w panels in series recently, on the grid but don't tell anyone, and noted they were all equipped with MC4 connectors which I understand are 2.5mm2, and the 6 meter long cable leads were 4mm2. Was this good practice?

Not too sure about the 2.5mmsq for the MC4 connectors as it depends on the type, pressed metal or the solid machined type. If they made the things properly the pins would fit the full length of the mating socket resulting in the 4mm square solar cable almost touching the 4.35mmsq 6mm auto cable or 4 mm solar cable if you want to spend the extra $$ for smaller cable We have changed to punching the pin/socket out of the plastic bits, slide a piece of heat shrink over the cable, push the pin full depth into the socket and soldering the joint for a positive connection and this has solved the dodgy MC$ connection problem.
Solar installers can't seem to get their heads around the difference between series and parallel when it comes to required cable size, series connection 4mm sq conductor is fine, but parallel with a cable run of around 5 mtrs the 4 mm sq cable would be maxed out at around 150w, yet you see 250w 12v panels with Y connectors linked all the way across the array and 1 4mm sq cable on to the circuit breaker.
This is where the MPPT controller legends come from, this totally inadequate wiring is then changed to series connection and fed into an MPPT controller nd suddenly the output is more than doubled. Nothing to do with the controller and everything to do with crap wiring, but the practice continues.

T1 Terry

[shonky]

Hi.

T.I.Terry - must admit I personally cut out the MC4's when I can. Now I'm not being tight-fisted, but the best butt crimps IMHO are 3cm lengths of 4 to 6mm copper tubing, bought from your local junkyard and cut to size. Crimp the crap out of them, double up on the heat shrink, and there you are.
BTW I hook up a cheap 1 kilowatt inverter to the batteries directly for the grinder.

[T1 Terry]

The reason we use the MC4 pin and socket is the ease of disconnecting and reconnecting a replacement if needed or just relocated to make room for more panels. The problem with copper tube is getting it clean in the first place and then keeping the corrosion/oxidisation out as the joint will produce a lot of heat once the oxide coating starts to build dragging in moisture as it cools, that is why copper cable lugs are tinned, so the oxidisation doesn't start the down hill spiral resulting in a failed joint. If the copper is not tinned then solder the joint and that will tin the contact faces

T1 Terry