I have two sites I'm erecting solar hot water panels. I've got my plumbing routing figured out (after much noodling) and chose to use 2" Sch40 pipe everywhere (likely overkill but nice if I ever split off to additional arrays).

I'm still not sure how I will attach the main valve array to the side of our deck.

My current idea is to use plumbing tape (metal with holes) wherever I can attach to deck lumber. However most the valve section will be below the deck floor. For that area I'm planning to buy some plastic trellis to visually block the entire under-deck area plus provide nice area to strap piping to. Probably will work but thought I'd post in case the collective wisdom has any additional thoughts.

Plumbing details:
The heart is the valve section (looks like a 2'x2' square with ball valves to direct to solar or bypass). I'm mounting it vertically just under north edge of our deck (about 4' away from pump & filter). Vertical for easy access, drainage, and space saving.
From there I'll run one set of pipes up above our deck where I'll have 10x17 area to mount ~4 4x10 mats.
Another set of pipes goes under the deck to South side where I'll mount two 2x20' SunHeater solar panels almost vertically against my south deck rail. (I know it would be better if I can slope, but space is a bit of a premium with no room to just rest on the ground.)

Let me know if you have any feedback. Thanks! -z