Abstract: An inclined heat absorptive and conductive panel including downwardly opening inverted V-shaped grooves formed therein extending downwardly from the upper end portion of the panel toward the lower end portion of the panel is provided. In addition, structure is provided for introducing a heat absorptive liquid into the upper end portions of the grooves and second structure is provided for receiving and collecting liquid from the lower ends of the grooves. The cross sectional shape and size of the grooves is such to allow at least substantially all of the liquid introduced into the upper ends thereof to be retained therein by the cohesive and surface tension properties of the liquid during its movement downwardly through the grooves by gravity toward the lower end of the panel. The panel comprises an inclined partition secured across the interior of an upwardly opening housing and a substantially fluid tight cover is secured across the top of the housing above the panel.