<p>The solar heat collector (1) has an insulated enclosure (3) with a glass cover (4). An absorber (2) containing the fluid to be heated is separated, from the glass cover by an air gap (5). A container (6) is connected to the air space (5) of the solar panel. The container consists of a thin-walled copper cylinder (13) filled with a dessicant (7). Holes (14,15) in each end of the cylinder provide a connection from the air space through the dessicant (7) to atmosphere. The cylinder is housed in an outer transparent enclosure (16) held between steel end plates (17,18). Moisture adsorbed by the dessicant during the night is rejected to atmosphere during periods of sunshine when the air in the air space (5) expands and causes a flow to atmosphere over the dessicant.</p>
