100w Solar panel update Dodgy factory wiring?????????

TrevandJenny

TrevandJenny

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Today I collected MH from storage with full intentions of removing factory fitted 80w panel and making ready to replace with the new 120w.
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After getting up the wobbly ladder to the roof I found under the 80w panel a pair of MC4 connectors from panel wire to factory fitted wiring, Brilliant says I this saves loads of work can use this for new panel, However best check out inside.
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The wiring from MC4 connectors went through the roof to a join, then twin wire to EC328 panel. My point, Victron panel wiring to MC4 connectors seems 2mm, Factory fitted twin wiring ( Round white household cable, brown & blue outer sleeves ) through roof to join seems 1mm, Twin auto wiring from join to EC328 panel 2mm.
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Yes I am mechanical not electrical but. 2mm to 1mm to 2mm, factory fitted cant be right. I am ripping it out in the morning weather permitting.
 
Victron cabling on a 80W panel probably 2.5mm solar cable. Pretty standard and fine.
for the size of panel - and also what the Sargent Controller can support - 1mm cable is just about ok and good enough for a 80W panel. 1.5mm would be better. if twin blue+brown and no yellow/green, chances are it is 1mm domestic lighting flex.

All seems pretty typical factory minimal wiring :( I think I would replace with probably 4mm Solar Cable to give some future-proofing.
 
At least the voltage is higher from panel to controller and whatever drop there is won't affect the output voltage.
It's crucial to keep the drop low from controller to battery and that's where skimping at the factory on cable size and potentially long run will probably hit performance.

My van was too old to have a built in controller but the after market unit had been installed next to the main Sargent PSU which was a 4-5m run from battery - although to be fair the factory wiring wasn't too bad.
When I later installed my Votronic controller I put it 1m from the battery with 6mm² leads and spun the solar panel round and reduced the run to the controller by 2m.
It also halved the run to the starter battery whilst on trickle currents that wasn't a big deal but every little helps!

I can't quantify the improvement but I'm sure I gained something for the few hours work I put in.
 
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Markd said:
At least the voltage is higher from panel to controller and whatever drop there is won't affect the output voltage.
It's crucial to keep the drop low from controller to battery and that's where skimping at the factory on cable size and potentially long run will probably hit performance.

My van was too old to have a built in controller but the after market unit had been installed next to the main Sargent PSU which was a 4-5m run from battery - although to be fair the factory wiring wasn't too bad.
When I later installed my Votronic controller I put it 1m from the battery with 6mm² leads and spun the solar panel round and reduced the run to the controller by 2m.
It also halved the run to the starter battery whilst on trickle currents that wasn't a big deal but every little helps!

I can't quantify the improvement but I'm sure I gained something for the few hours work I put in.
Click to expand...
One thing you have to watch out for wiring sometimes is to not go overboard, especially if you happen to fit Victron kit. For example, the Victron 100/20 (290W Controller) won't accept 6mm cable as it is too large! One of the annoying things about Victron :(
 
When I replaced the 30 watt solar panel with a 120 watt solar panel on our old Autosleeper Broadway ( 2013 model), Autosleeper had wired from the panel connectors to the Sargent controller with cable that couldn’t have been more than .5 mm. it was like cheap speaker cable. I rewired the lot with swg12 cable ( 2.6mm).
 
snapster said:
When I replaced the 30 watt solar panel with a 120 watt solar panel on our old Autosleeper Broadway ( 2013 model), Autosleeper had wired from the panel connectors to the Sargent controller with cable that couldn’t have been more than .5 mm. it was like cheap speaker cable. I rewired the lot with swg12 cable ( 2.6mm).
Click to expand...
As mentioned earlier the middle cable was household domestic twin core. Weather today stopped work on MH as to wet to fit panel.
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The markings on cable on new panel is 13awg with 5mm x 2. Much thicker than previous. Did you wire up to the Sargent control or fit a new controller when you fitted new panel?
 
I had to cobble together some new connectors to take the thicker cable, but it seemed to work fine
 
I have obtained original pins for male plug, I intend to solder cable to pins to overcome the size issue. Panel fitted now, is a shorter cable to controller wise or is it only cable to battery that needs to be as short as possible.
 
There will be voltage drop in both runs.
But a decent (MPPT) controller will still deliver correct voltages on output side but drop on run to battery terminals will affect performance.
So voltage drop on input is less critical than output but if have spare cable cut it out!
 
Have just finished all the wiring. I shortened the cable as Markd suggested from panel to controller. From controller to batteries is less than a meter, not able to decrease it. Removed power cables from batteries and refitted solar cable to controller, replaced battery cables, well pleased with the 120w panel not a great day here but voltage increasing steadly.
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With the higher gauge cable and 120 watts it seems without a doubt more efficient.
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Thanks for all suggestions and advice
 
1m from controller to battery is pretty good.
At 120w the current during main charge phase (c14v) is 8-9 A so a short run and decent sized wire will make a difference.
Good to hear it's up and running - all we need now is some sun 😀
 
Markd said:
1m from controller to battery is pretty good.
At 120w the current during main charge phase (c14v) is 8-9 A so a short run and decent sized wire will make a difference.
Good to hear it's up and running - all we need now is some sun 😀
Click to expand...
that's the tricky thing about winter solar installs & upgrades ... hard to really judge how well they worked. the theory generally translates into reality though :)
 
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