Hose/pipe length for solar panels

[Poconos]

Home Depot etc. have black poly pipe in 100' rolls really cheap. For lowest flow resistance you also want to use the largest diameter that is reasonable. One drawback is you can't make sharp bends but there is an assortment of barbed fittings for the stuff. I buried a couple 1.25" lines to my field solar array that is about 80' from the pool and up 10'. The array is 1200' of the black 1/2" stuff. Works great. As for the angle of the panel the optimum angle depends on your latitude but about a 30 degree angle will work better than laying it flat. But you are usually limited in what is reasonable from fabrication, practicality, and cost considerations.
Al

[cleancloths]

From my experience you are better off going with 1.5" rather than 1.25" as the latter is an oddball size and is just about the same price as 1.5" which will handle much more flow or give you much less of a pressure drop.

[porkypete]

That answers my questions. Thanks all for your replies!