Solar Panel positive/negative wire?

Anything DC is 'kinda picky' about polarity.

Thanks for the info guys.

Will do exactly as you say.

Glad I asked lol!

It’s a big deal! Be careful.

Yes it matters. They should be marked, but if not, put your multi-meter on voltage across the two wires with the panel facing the sun so there is some voltage.

If you have pos to pos, the meter display will say, eg 34.2, but if you have neg to pos, the meter display will say - (minus) 34.2. So now you know which wire is which, put some red sticky tape on the panel's pos wire.

You must get polarity correct or the controller can be damaged.
Trace them out and still check twice with a meter just before you connect.
Controller to battery polarity is just as important. Also connect controller to battery before you connect the power from the panels.