So the only way this is going to work is if you put the storage tank above the collector, and the path of the cold water has to come out the bottom of the tank and flow down hill to the bottom of the collector before it starts to get heated. Then the hot water has to flow up hill the whole time. If you put any loops that go back up hill for the cold, or down hill for the hot, it won't work. Also you would be good to take the pipe and manifold it out so there is less resistance..
Also, 40 feet of copper pipe isn't going to do much..