a combination form of flexible roofing material including a reinforced single - ply membrane base for being adhered to the roof substrate . on the base is laminated a structurally flexible layer of solar cells encapsulated and sealed in a flexible intermediate layer of solar radiation transparent plastic protected by a cover layer of weather - proof solar transparent plastic . the roofing is constructed for being manufactured in elongate sheets , rolled up for transport to the site and installed by conventional methods including sealing to adjacent sheets of similar single - ply membrane material which may or may not incorporate solar cells . this is continued until the roof covering is complete . examples are given for reinforced plastic sheet , modified bituminous sheet , and elastomeric sheet roofing materials as well as for a wide variety of solar cells materials together with methods for fabricating these materials into the roofing system disclosed .