I thought I would throw a question out and see what the prevaling thought is.
I currently have a 3/4 hp sand filter combo for my 9x18 pool. I have hard plumbed to pump with 1.5 pvc. My return is also 1.5 but I have a "T" to a 1/2 inch that goes to my roof. There is a ball valve above the "T". The 1/2 inch pvc goes into about 200 feet in 2 separate coils of black thin walled 1/2 in tubing then returned to the pool via another 1/2 in pvc pipe. Pump pressure sits at about 8 which is about 3/4 into the green on my pressure gauge. Flow is continually4-5 degrees above pool temp. so its working. Small flow, but never the less working.
After looking at some of the commercial solar setups I thought I would consider this:
1) convert T to roof to 1.5 in with ball valve.
2) build manifold at low end of roof with 4 inline 1.5 to 1/2 in T's with end cap.
3) from each 1/2 in nipple feed a 100 ft coil of 1/2 in black tubing.
4) top manifold would be same as lower except plumbed directly into the pool return instead of separate feed.
I don't know enouph about the math involved to see if this would work. I do know that the thin wall pvc is cheap
And the stuff I currently use has been on the roof for 4 yrs.
Looking forward to your thoughts..