Frank,
How about just using black hose running in a back and forth direction from the bottom of your roof to its apex, with a temperature sensitive valve at the apex point, and a black hose, from the apex, running down the sunny side of your house into the hot water container in your basement. When the water at the apex of your roof attains a pre-selected temperature the valve opens and lets waterenter the system from the low point of your roof pushing the water into the container in the basement, until the temperature at the apex lowers to a predetermined temperature and shuts off. Repeat. Bob snip Thanks Bob. The problem is that cold water must then be lifted to the roof from the basement. It takes lift to get it to go up.
