TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - The hot melt sheets comprise fillers, which match the refractive index of the sheet material and/or are dispersed particles of a size smaller than 1/4 the wavelength of light selected from wollastonite, silica, titanium dioxide, glass fibre, hollow glass spheres and clays.    TECHNOLOGY FOCUS - POLYMERS - The hot melt material comprises a blend of linear organopolysiloxane polymer and a silicone resin which are adapted to cure in the presence of an initiator or catalyst/cross linker system. The hot melt material comprises component (A) having a high molecular weight di-organopolysiloxane also referred as silicone gum having at least two reactive groups per molecule, which reactive groups are designed to cure with component B where possible; component (B) having a silicone resin (MDTQ) or mixture of resins containing reactive groups which will interact with component (A) in the presence of component (C) that is suitable curing package which is chosen to cure the interactive groups between components A and B, typically the cure system is chosen from the most appropriate curing package(s). The reactive groups in both components (A) and (B) are unsaturated groups and component (C) is a hydrosilylation catalyst in combination with a cross-linking agent in the form of poly-organosiloxane having at least two silicon-bonded hydrogen atoms per molecule. The component (C) is an organic peroxide. The hot melt material comprises thermoplastic block copolymers obtainable by mixing a hard segment comprising a polymer having a glass transition point greater than the operating temperature of the photovoltaic cell module and a soft segment, in the form of an organopolysiloxane polymer having a glass transition point less than the operating temperature of the photovoltaic cell module. The thermoplastic block copolymers are selected from the group of silicone-urethane and silicone-urea copolymers. The additives are selected from co-catalysts; optical brighteners, rheological modifiers; adhesion promoters, pigments, heat stabilizers, flame retardants, UV stabilizers, chain extenders, electrically and/or heat conductive fillers, plasticizers, extenders, fungicides and/or biocides, water scavengers, and pre-cured silicone and/or organic rubber particles.