After ten years of research, in May, Switzerland-based SwissINSO and its partner the Ecole Polytechnique Federale de Lausanne announced its BIPV revolutionizing colored PV panels coyly adding that the panels would only be slightly less efficient than traditional PV modules. Other than the obvious questions as to what does slightly mean? – As well as in comparison with what traditional PV technology? – The question, what exactly is new about this? – springs to mind. The concept of colored modules is not new to PV. In 2002, Automation Tooling Systems and its Ontario, Canada, subsidiary Spheral Solar Power Inc. announced the near-term commercialization of their Spheral Solar PV technology. In development since 1983, the Spheral Solar cell involved the lamination of two sheets of aluminum foil encapsulating small silicon spheres. At the time proponents of the technology noted that it offered stability and performance similar to single- and multicrystalline technology, along with the applicability of amorphous silicon technology for the growing BIPV market. The manufacturing process for this technology used two elements, aluminum and silicon, and involved a two-stage process. In the sphere fabrication process, the silicon feedstock was purified and formed into a spherical shape. The feedstock entered an open-air furnace, where a layer of oxide formed on the surface. The silicon melted in the second stage of the furnace, with the oxide layer forming a skin. On cooling, the spheres formed single crystals. Following this stage, the spheres underwent several standard semiconductor processes. The first process created a “p”-type sphere; followed by a diffusion process whereby an “n”-type layer was added. In the cell fabrication process, a large sheet of aluminum foil was perforated with thousands of tiny holes, into which the spheres were loaded, and then bonded in a thermo-mechanical process. A backside etch removed the n-type layer to expose the p-type core. A thin layer of polyamide was applied to the back and cured to form an insulation layer. The cells were joined in a series by welding the front aluminum foil to the adjoining back aluminum foil. The Spheral Solar technology pedigree began with Texas Instruments and included Ontario Hydro and Canada’s Automation Tooling Systems (former owner of Photowatt) before being shut down in the mid-2000s after failing to revolutionize the BIPV market.
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