Abstract: A solar heater for water or similar fluids comprises extruded semi-rigid plastic panels containing a plurality of adjacent tubular channels adapted to conducting fluid longitudinally through the interior of the panel from a transverse inlet manifold to a transverse outlet manifold. Flow-restricting passages between the manifolds and channels tend to equalize the flow rates through each channel. Integral with the upper surface of the panels is a plurality of parallel, longitudinally-disposed, triangular cross-section ridges adapted to absorbing solar energy. Solar energy unavoidably reflected from the plane surfaces of the ridges is partially absorbed by adjacent ridge surfaces, increasing the energy absorption efficiency of the panels.

Abstract: A solar heater for water or similar fluids comprises extruded semi-rigid plastic panels containing a plurality of adjacent tubular channels adapted to conducting fluid longitudinally through the interior of the panel from a transverse inlet manifold to a transverse outlet manifold. Flow-restricting passages between the manifolds and channels tend to equalize the flow rates through each channel. Integral with the upper surface of the panels is a plurality of parallel, longitudinally-disposed, triangular cross-section ridges adapted to absorbing solar energy. Solar energy unavoidably reflected from the plane surfaces of the ridges is partially absorbed by adjacent ridge surfaces, increasing the energy absorption efficiency of the panels.