A 12V battery master switch of most any description should work fine; it sounds like a maximum current on the order of 30A. Even a simple knife switch of appropriate size would be okay. Boat parts and racecar parts and similar places should have something perfectly satisfactory; probably also ordinary auto parts stores.
If you switch the panels off at night, there won't be much if any current being switched which will be gentler on the switch. That probably doesn't matter in practice since you aren't going to be frequently switching the panels in and out.