So here's another obscure installation tip. Heliocol panels have stringers, placed about every foot or so, that do two things. They keep the little tubes aligned, and they function as spacers between the tubes and the surface on which the panels are mounted. In Dog's pic, you can see how his tubes are laying on the metal bracing. As the panels heat and cool, they expand and contract, and so rub across the metal bracing. This causes undo wear to the tubes and can cause premature failure. This is much more of an issue if your panels are mounted over typical roofing material (concrete tiles, asphalt shingles, etc) because those roofing materials are much more abrasive.
Dog, it looks like your panels also have some sort of stringer. Your panels would be better off if their stringers were touching the metal bracing, instead of your tubing. Booshy, this is something to consider, depending on how you've mounted your panels. Only the stringers should be in contact with the surface of your mounting structure, the tubes should stand off from everything, so when they expand and contract they don't rub on anything.