Solar wiring question

Jonnygsx wrote:

...Initially Im only going to be running one 120watt evergreen but I would like to wire suitable for at least 3 panels.

The wiring plan I am beginning to settle on was a junction box on the roof with a 10guage to 6 or 4 guage terminal. Running that through the roof of the bedroom at the front of the trailer and then going to the controller on the backside of the front wall of the trailer. Then going 4 gauge to the batteries which would be less than 5 feet away.

How much space do I need around the controller, is it like a converter where it can get very hot? My trailer has a cover over the propane tanks on the front but it isnt very protected. I would guess its better to have the controller inside the trailer than under this cover outside?

Your initial plan is very similar to the way I approached it. I initially planned to install one 140 watt panel but wanted room to grow without having to rewire if/when I did. Seems like MC4 connectors only go down to 12 gauge so that is what I used for panels to a junction box on the roof. Then 4 gauge from the junction box to the controller (about 15' of wire length) and 4 gauge from the controller to the batteries with about 5' of wire length. I went with a Morningstar Tristar 45 PWM controller and I really like it. Its terminals can handle up to 4 gauge and it uses temperature compensation. I ended up starting with 2 x 140 watt panels due to sale price and I have not added any more. So my wiring and controller are quite a bit oversized for my current needs, but I have the capacity to expand. The same panels have gone on sale again a few times since then and I've been very tempted to expand just because I could, but I put the money into new batteries instead which I think was the right choice. You need a nice reservoir to store the power in before going wild on the harvesting capacity.

Regarding your original question for the thread, it is best to put the controller as close as possible to the batteries due to voltage drop. So if you can't get close, compensate with oversized wires. My dad's TT, which is our old TT that I mentioned in one of your other threads, had it's controller output tied into the converter output wires. I'm pretty sure the original owners had the solar installed by the dealer when new and they did it as quickly and easily as possible. I watched a demo video of dealer installers putting in solar and that is exactly how they did it. This is not ideal due to long wire length and associated voltage drop. From what I gather, and from what is in my and my dad's TT, the wiring from the converter to the battery isn't even sufficient to let the converter work optimally. For one 120 watt panel it is probably OK, but since you're planning for expansion I would suggest using wire you know is fat enough.