Solar collector with modified plumbing and array thereof

In a solar collector comprising an enclosure having a transparent front face, a solar energy collector plate spaced from and parallel to said front face, heat transfer fluid passageways in thermal connection with said plate, and heat transfer fluid inlet means and outlet means disposed to communicate with said passageways and to be connected with external heat transfer fluid plumbing through said enclosure, said external plumbing in turn being connected with a means for circulating heat transfer fluid to and from said collector at a predetermined rate, the improvement consisting of:

• said collector being adapted to be mounted in a sloped position with said inlet means and said outlet means both located on a lower edge of said collector enclosure, said collector including a downflow conduit for receiving heat exchange fluid from said passageways and for conveying said fluid from said passageways to said outlet, said downflow conduit sized, relative to the fluid throughout rate of heat exchange fluid to and from said collector, to produce sufficiently high heat transfer fluid linear velocity in said return conduit to prevent air bubble or vapor blockage of said return conduit to prevent air bubble or vapor blockage of said passageways in said conduit within said enclosure by establishing a downflow velocity in said conduit in excess of the terminal velocity of a bubble in heat exchange fluid in said conduit.