Solar wiring - Where to drill the hole

[coopc]

Hi I fitted a 130w solar panel to my Fiat Ducato based Carado T447
At the time I just routed the wiring in via a roof vent
Now I need to fit the wiring correctly and am having trouble on how/where to cut the hole and would like some guidance/suggestions
The biggest issue is where to drill so it comes out in the right place inside van
I was going to try and remove internal B post panels etc and route through there and try and find a suitable place to drill above but I feel whilst this will be neater it will add complexity to the task ?
The inside panels trims etc make it impossible to measure the inside to match measurements outside - so how do people decide where to drill hole ?
Is there a tool like a stud finder to pinpoint the exact spot
I was considering using strong magnets and placing inside and seeing where the apposing magnet would be attracted/repeld on the outside - would this work ? what strength magnet would be needed
Any other ideas other than rough guess and drill !!

Thanks

 

[Orion]

Is it totally impossible to gauge and access the internal entry point? Otherwise measure twice (thrice and ten times!) and drill a pilot from inside to out and take it from there.

On my recent similar escapade I drilled at 45 degrees rearward to take account of the cable routing through the entry gland/cover and it worked out perfectly.

 

[Tombola]

I used a pilot from inside out, after mearsuring a good few times top and bottom.
on another note though, you do know that cable position you were using will cancel most of the solar output with the shadow it causes dont you ?

 

[Gasgas]

As you say, you can't measure from the panel to the outside wall because of insulation and so on. And on a panel van of course you have the internal structure strengthening 'beams'.
You need a datum point which is evident both inside and outside and what I would do if I were you would be to use the roof window frame. You can measure from this both inside and outside.

 

[TheBig1]

2 pieces of string. measured from the corners of a skylight. Knot at the point where you want to drill, measured from inside. Move the string outside from the same two fixed points. This will be the same spot inside and out

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[Stealaway]

First of all.
Are you drilling the hole above where the solar controller is going to be - and next to the leisure batteries?
Try and access the route down to the solar controller with a pull string behind any panelling/void before deciding on the hole position.

 

[berni109]

It's obvious where u are trying to get from but where inside are u trying to get to?
U can push the drop cables behind the plastic on the b pillar without having to remove it first.

 

[Mikeco]

You don’t want to see the wire so it has to come into the van inside a cupboard or perhaps the wardrobe, as already said it depends where your controller and batteries are.

 

[Minxy]

In my previous PVC I drilled into the corner of the overcab storage near the B pillar, I then fed the cables through from the roof and to the side into the top of the B-pillar and down behind the plastic trim, by drilling into the overcab there was more tolerance and meant a slight mis-measurement wasn't so vital, not that I got it wrong but if I had it would have been easier to sort it rather than trying to disguise a hole in the wrong area of the visible roof.

 

[jwells]

I am about to try and do this exact same thing on a brand new Auto Trail!!

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[Kybod]

Decide the route you need to take, to make it neat, usually inside a cupboard. Then as already said, measure a few times and then drill a pilot hole from the inside to the outside. Hopefully, all is how you planned, then drill a larger hole for your cable from the outside to inside.
When I was younger I fitted hundreds of sunroofs onto brand new cars. This could be scary if it was something new but working methodically saved me from embarrassment

 

[Jev88]

I chose something on roof like toilet vent or fridge vent (RV) and measured from that externally and repeated internally.

 

[Minxy]

I am about to try and do this exact same thing on a brand new Auto Trail!!

It's easy peasy compared to drilling a great big hole to install a through the roof telescopic TV aerial! I waited until hubby was at work to do it as he had kittens when I'd previously fitted a bike rack.

 

[Minxy]

2 pieces of string. measured from the corners of a skylight. Knot at the point where you want to drill, measured from inside. Move the string outside from the same two fixed points. This will be the same spot inside and out

That's pretty much how I did it but it was a little bit more complicated by shaping on the roof of the camper compared to a flat MH roof so double checked with a tape measure as a back-up.

 

[coopc]

I used a pilot from inside out, after mearsuring a good few times top and bottom.
on another note though, you do know that cable position you were using will cancel most of the solar output with the shadow it causes dont you ?

Yes your right the cable routing over the panel was not ideal but served its needs of keeping both engine and leisure batteries topped up enough over winter
I did not have a flat engine battery like previous yrs

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[coopc]

Thanks everyone for the great suggestions
The string method is one I used to use 40 yrs ago - I fitted lots of sunroofs in VW/Audi cars and use string then - completely forgot about that !
The controller is directly below the passenger seat so B pillar routing would be ideal otherwise trunking which would hardly be noticed
When the weather breaks I will get down to the van and drill that hole !!!!
Thanks again

 

[siiva]

Is it bad form to revive an old thread?

I'm wondering: What is "b pillar"? In Switzerland, this is a type of retirement fund

 

[Minxy]

A "b pillars" are the structural support that runs behind the cab doors, the one either side of the windscreen are the "a pillars".

 

[CAB96]

Is it bad form to revive an old thread?

I'm wondering: What is "b pillar"? In Switzerland, this is a type of retirement fund

As Minxy said.

They go from front to back.

A pillar on the windscreen, B pillar by the front doors, then C and maybe D pillars as you move back along the car or van.

Usually only need to specify A or B pillars.