An integral collector-storage solar water heater and associated evaporation and temperature limiter

A core (30) for an integral collector-storage solar water heater has a first tray (40) which acts as a solar absorber and an opposed second tray (42). The trays (40) and (42) are configured to form opposite sides of a liquid tight storage tank (44) when joined together in a mutual overlying relationship. A plurality of joining ribs (60b) is provided internally of the tank. The joining ribs (60b) are configured to enable joining of the first tray to the second tray at multiple locations within the tank. A passive limiter (32) is coupled to a vent of the core (30) and acts to limit the temperature inside the core and minimise loss of energy storage liquid within the tank (44) through vaporisation.