What gauge wire?

I wouldn't use less than #4 if the panels are in parallel. Welding cable is very flexible, UV resistant and no more expensive than big box store wire.

I wired all of my solar with #4 welding cable (about $1/ft.). I terminated everything with good lugs I bought at an electronics surplus outfit except for the connection terminals to the controller. For that, I sourced spade terminals from an online car audio supplier.
The cost of the wire is trivial compared to the installation labor and the anticipated loss of power with smaller wire throughout lifetime of the system. Using small wire for solar is like buying cheap paint, it's a false economy.

Why put in high end Kyocera panels and cheep out on wire? 40 feet is a long way from the battery with a lot of voltage loss that you will never get back. Such a waste. If this is just going to be a battery maintainer, your little bitty #10 wire will be fine but if you are going to do some serious off grid camping, then go with at least # 4 cable as suggested. I have helped 3 others replace their factory installed #10 wire because their solar system didn't work as expected. In all cases there was big improvement.

I've thought about welding cable and wou?ld like to use that but the controller is setup for 8ga max best I remember. So how do I get around that?

Clip some strands off the end of the cable or you can use reducers.

Thanks, not a bad idea. Will be back home in a couple weeks so can check my local welding supply house for cable. Thanks again everyone for the replies.

An alternative is to leave the 35 ft, 10 awg cable in place and go serial. You now need a mppt charge controller. You may find a controller cheaper than new cable. If you go serial then the two panels have to match. 140W each.

That's not a bad option either but don't know what the controller would cost, have to check that.

What's the difference in the way they charge? Or the charge rate?

Hi,

#10 will be just fine with a pwm controller. I would add a temperature sensor.

Keith Haw wrote:
I've thought about welding cable and wou?ld like to use that but the controller is setup for 8ga max best I remember. So how do I get around that?

I bought gold plated connectors like these. They are cheap and effective.