Wall element comprising a solar collector which is disposed between two transparent panes

A wall element comprising an outer transparent pane and an inner transparent pane parallel to each other and providing an enclosed space therebetween;

• a number of sealed and evacuated transparent tubes paraxially arranged in said space, adjacent transparent tubes being in contact with each other, the inner surface of the longitudinal half of each transparent tube facing the outer transparent pane being provided with a selective heat-reflective layer;
• a tube for a heat energy transport liquid arranged axially in each transparent tube in sealed relationship therewith;
• an elongate metal absorber plate rotatably mounted on each heat energy transport liquid tube in heat-conductive contact therewith, one surface of said absorber plate being provided with a non-selective absorbing layer and the other surface of said absorber plate being provided with a non-selective reflective layer;
• and means to selectively position the absorber plates (a) with their non-selective absorbing layers parallel to the outer transparent pane to provide an active solar heating system, (b) with their non-selective reflective layers extending transversely of the transparent panes and facing upwardly to provide a passive solar heating system, and (c) with their non-selective reflective surfaces parallel to the outer transparent pane to provide a radiation heating system.