Combined collector storage system for solar water heating

摘要

A solar water heating system comprises a cylindrical tank (vessel) within an enclosure consisting of a curved reflective sheet at the rear and a highly insulating transparent cover at the front. The system is also insulated at the rear; the insulation may be in the form of layers of fibrous insulation, such as fibreglass. Preferably, the tank is made of copper and has a spectrally selective surface, with high short wave solar absorbtivity and low long wave thermal (infrared) emissivity, applied to its exterior surface by chemical processing or by the application of an adhesive foil. The reflective sheet may comprise a flexible surface with a highly reflective coating on its concave side, with an essentially semi-circular profile. The transparent cover may comprise a glazing unit consisting of a sealed double glazed unit with a low emissivity coating and with a low conductivity gas, such as argon, filling the gap between the two panes of glass. Preferably, the solar water heating system is integrated into a sloping roof by inserting it between the rafters of the roof so that the outer face of the collector lies flush with the outer surface of the roof. Cold water from a mains supply may be fed into the bottom of the tank whilst warm water is delivered by an output pipe located at the top of the tank. The warm water delivered by the solar water heating system may be instantaneously heated up to a required delivery temperature by an electrical heater fitted between the cylindrical tank and the taps in a house. In use, the system is designed to be simpler and cheaper than conventional solar water heating systems, whilst being integrated into a roof surface, so as to be unobtrusive, and delivering warm/hot water at mains pressure.