Replacing factory pre-wire

[memilanuk]

Recently sold the 30' TT and got a slide-in truck camper. The TC came with 'solar pre-wiring' from the factory... that I'm not too impressed with. Probably need to get it addressed before I continue onwards.

Basically they put a cable entry gland up on the roof, with MC4 connectors, and then ran some wires down inside an interior vertical cavity to the general area where the load center panel is, and capped them. It looks like they ran PV wire only as far as needed (about a foot or so into the cabin), then butt-spliced the PV wire to regular #10 with cheap automotive splices. Just to make it more interesting, *those* wires are also butt-spliced again about another 12-18" down, again with cheap splices, no extra head shrink, etc.

So... my questions would be: is it typical to switch from PV to regular wire using butt-splices like that? If not, what's the recommended approach? Have a terminal block and swap over there, or run the PV wire all the way to the solar charge controller? If it were yours, how would you fix it?

Thanks,

Monte

 

[time2roll]

If access is easy I would probably pull MC4 wire to the controller to avoid the splice connections. If it seems difficult I would probably go as is and see what works. I would not be that concerned about no heat shrink unless exposed to moisture or strain relief was needed.

When I wired my trailer I used an MC4 extension cable and cut in half. Connectors to the panels, cut ends to the controller.

 

[Boondock Saint]

pull MC4 wire to the controller to avoid the splice connections

 

[chrisski]

Properly used, I see nothing wrong with butt splices. A picture would be better, bit the way you describe them, that is not a good use of a butt splice.

As you move forward, there may be some limitations with the pre-built wiring. THe first is it seems one series of panels only, or they need to be combined on the roof. The second is MC4s are rated for 30 amps with 10 AWG wire. Provided you do have 10 AWG wire, that limits you to about five 100 watt panels on the roof in parallel. Of course you can put them in series to get around the wattage limit.

The more I hear about these solar pre-wired trailers, I’m pretty happy I was able to cut a hole in the roof and floor and put an oversized conduit in to run wires up and down. I even have more room in the conduit to run something to the top like satelite dish.

If you’re finding this pre-built wiring a bother, cutting a hole in the roof and floor for a conduit is not that hard.

 

[eXodus]

As you move forward, there may be some limitations with the pre-built wiring. THe first is it seems one series of panels only, or they need to be combined on the roof. The second is MC4s are rated for 30 amps with 10 AWG wire. Provided you do have 10 AWG wire, that limits you to about five 100 watt panels on the roof in parallel. Of course you can put them in series to get around the wattage limit.

depending on the roof layout I would go straight for a 200w or 400w panel.

Then you don't really care about the 30A. Those panels come in at 35-60V each. 30A is a lot of power - just get the voltage up.

 

[stewchi]

I would butt connect the from the end of the existing cable at a section that is easy, ideally removing any suspect splices. If you are running MPPT you can put them into Series and the length of the 10G wont be an issue. I am running 8 panels 2 sets of 4 in series. Max current is around 6A for around 355 watts.

 

[HRTKD]

The switch to cheap wire is odd. From a labor perspective, it takes less time and should cost less to use PV all the way rather than put in two splices.

If you have reasonable access to replace the wire, I would do so. I'm a bit OCD about it and the splices would bother me. I ran 10 gauge PV all the way to the circuit breaker that is located about 18" from the solar charge controller, then 6 AWG from the circuit breaker to the solar charge controller.

 

[rmaddy]

PV wire is regular wire with an extra protective layer. That extra layer is really stiff compared to the regular wire. When I wired up my cargo trailer I ran my PV wire to within about a foot of the disconnect breaker leading to my charge controller. The PV wire wouldn't bend enough to wire up my breaker so I cut the PV wire short and butt spliced non-PV marine grade wire using proper marine grade, heart sink butt splices. This made the rest of the run much easier.

So I see no problem with a butt splice to switch to regular wire inside the camper. But for peace of mind I would redo your wiring with a single, proper butt splice and eliminate the low quality job you found. Plus you will feel better knowing that run is made with quality wire that you installed.