1.2 SUMMARIES ON THE STATE OF THE ART 1.2.1 Power Conversion (References: 76/1,76/2,76/3,77/2,78/12,78/19,78/55.) I.2.1.1 General This category implies the conversion of solar radiation power into electrical DC power within the SPS. This includes optical solar-thermo-electric and photovoltaic devices. Not implied are nuclear-thermo electric and directly solar powered laser or maser devices. 1.2.1.2 Solar-Thermo-Electric Conversion In this sub-category six methods appear worth to be mentioned : - Thermionic conversion - Combined thermionic/Brayton cycle conversion - Brayton cycle turbomachine - Rankine cycle turbomachine - Cascaded dielectric device - Magnetohydrodynamic conversion The thermionic conversion appears not to be feasible for a long reliable working period mainly because of the required high temperatures. The Brayton cycle has been considered as the most promising method within the thermo-electric conversion sub-category because the single phase working fluid precludes internal system corrosion. The cascaded dielectric conversion device is only mentioned in reports of the inventors. So it is not possible to be classified within this range. The Rankine cycle is no longer seriously considered as a competitor to Brayton conversion because of the corrosion problems due to the liquid metal working fluid. The development state of the MHD device is not sufficiently advanced, so it is not possible to criticise it. 1.2.1.3 Photovoltaic Conversion In this sub-category the following cell types must be mentioned as the most promising ones: - Single crystal silicon cells - Polycrystalline silicon cells - Amorphous silicon cells - Gallium Arsenide Cells In addition to thesezCadmium-Sulfide cells appear to have a certain potential for SPS-application.
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