For clarification--Waytek Wire is a distributor of electrical products. I don't think they make anything, at least there is no factory at their headquarters location. I've bought a few things from them and pick up direct at their headquarters.
I built my combiner box and used a gray 1 1/2" PVC LB. I see these all day long on the sides of buildings near service entrances and they are all intact. I dunno', maybe in 50 years the plastic will dissolve (but I doubt it). Actually, my conduit run on the outside of the trailer is painted, to match the exterior color of the trailer. Psheww, dodged a bullet, I guess.
BTW, I also used 4 ga. welding cable from combiner to controller.