Abstract: A flexible quilt collects and absorbs solar energy, and transfers heat to the underlying ground, water or other medium. It includes insulating gastight compartments which are located between an upper film and a lower film. The upper film has a high transmissability of ultraviolet and infrared energy directed downwardly therethrough, and it is reflective of infrared energy impinging on its lower surfaces. The lower film is absorbtive of solar energy and is modified to enhance the thermal conductivity through its thickness. To promote heat transfer to the underlying medium, the lower film is deformed to increase its surface area, a plurality of downward projections extending from each area of the lower film associated with each gastight compartment.