Abstract: Lightweight, economical and highly effective solar energy collector panels are formed with a sheet of transparent plastic exposed to solar radiation and spaced by a rigid lightweight spacer frame above a sheet of metallic foil, which embraces in heat conducting relationship a spaced array of metal water-carrying tubes all supported by an underlying plastic foam slab, with the overall assembly being encircled by a channel section peripheral frame.By completing the panel assembly with foam material which substantially entirely encapsulates the panel components internally in an inexpensive, lightweight, and completely effective framed unit, a unique panel construction is achieved by a unique manufacturing process.