Abstract: A light weight support box is formed as a rigid beam from a single thin sheet of inexpensive plastic. The single sheet forms the bottom and side walls of the box and serves as the tensile member of said beam. The interior of the box is insulated to protect the sheet from thermal degradation of its tensile strength. The one-piece sheet, forming the walls and bottom, is secured at the open edge of said box to a reinforcing bar members to which beam compressive forces are transfered by the plastic sheet. The box is particularly suitable for roof top mounting of a passive solar water heating system, including either a solar collector, or absorber, panel or a hot water storage tank, or both in a back-to-back assembly.

Abstract: A passive solar heating liquid storage tank is formed of multiple thin sheets of thermoplastic or thermoset material to provide a lightweight, inexpensive and high volume tank. The multiple sheets have a plurality of parallel undulations or corrugations transverse to their surfaces. The undulations form spacial wave trains of given amplitude and frequency so that when their peaks are secured together they form generally parallel circular tubes. One of the pair of sheets has a third sheet secured to its surface. The third also has undulations in its surface with spacial frequency at least as great as the frequency of the wave train of the pair of sheets. Peaks of the third sheet are then secured to exterior peaks of the pair of sheets. Such construction forms a tank having the strength of parallel cylindrical tubes but with total volume approaching that of tubes having a rectangular cross-section.

Abstract: The present invention relates to a method of forming a solar collector, or absorber, panels or a heat storage tank, suitable for heating water using solar energy. It also relates to articles of manufacture so formed and to solar water heating apparatus using said articles. Three methods of forming the panel or tank from two sheets of uncured elastic material, such as EPDM rubber, by simultaneously bonding and curing such material around the peripheral edges of the two sheets and at spaced apart, discrete areas over most of the interior areas of the sheets. In one form of the method, one of the sheets is coated with a layer of release agent, over all areas except the discrete areas and the peripheral areas so that only such uncoated areas will bond during cure. In another form, a sheet of non-adherent plastic slightly smaller than the two sheets and having holes or holidays to form the discrete areas is bonded between the two sheets.