Abstract: A combined solar heating and insulating apparatus for use on existing buildings or in new construction. The apparatus is inexpensive to manufacture and provides for auxiliary solar heating during the day and insulation during the night, both of which result in a savings in fuel and increased efficiency of the standard heating system of the building. The apparatus takes the form of panels which can be affixed to existing vertical southern walls with little or no modification, thus allowing for the use of solar energy without expensive physical modifications to the building.