Solar wire connections

Install the heaviest wire possible rated for the current carried. To me, it makes little sense to have any voltage drop between the solar panels and the battery from insufficient wire. At least, minimize it as much as possible so that those harvested amps aren't being dissipated in the wire.

If it's possible, connect the solar controller's output directly to the batteries, only interrupted by the proper sized fuse. This will allow less grief in the future, should you have an issue with your 12 V system and you'll be able to disconnect the battery from parasitic loads, leaving your solar charging system to operate when in storage.

Well,IF the trailer gets back from the shoppe, I'm thinking about a 300 watt solar set up. I'm kind of handy with some things, and could install it.
Our "new" trailer had a solar panel (it was removed) and the wires came down the refer chaste and connected at the converter--thus the reason for the question. Personally, it seems to be smarter to connect the wires directly to the batteries.
Thanks all for getting back on this.
See ya out there

If you are installing a system over 200 watts it would be best to post the details and expectations for best answers.
Always best to have controller connected direct to the battery with short fat wire.
Some controllers are sensitive to getting disconnected from the battery before the power is cut from the panels. Easier to create an issue when you share systems.

BTW My 3 serial panels have 61' of wire for 0.6% drop. The CC output is connected to the charger with a 1.3% drop. A very respectable 1.9% drop.

And that is with full rated panel output and is rarely approached with flat mounted panels.

2oldman wrote:
Heat is a sign of wire that's too small. No heat, wire fine.

But there may still be to much voltage drop.

Get the wire size and length and run a wire calculator and find out the actual drop for your setup.

12V parallel panels with PWM may be more tolerant of voltage drop since they are usually about 18V. MPPT controllers can harvest the higher voltage and the voltage drop may be more important.

Heat is a sign of wire that's too small. No heat, wire fine.