Solar breeder: Energy payback time for silicon photovoltaic systems

Source: NTRS


The energy expenditures of the prevailing manufacturing technology of terrestrial photovoltaic cells and panels were evaluated, including silicon reduction, silicon refinement, crystal growth, cell processing and panel building. Energy expenditures include direct energy, indirect energy, and energy in the form of equipment and overhead expenses. Payback times were development using a conventional solar cell as a test vehicle which allows for the comparison of its energy generating capability with the energies expended during the production process. It was found that the energy payback time for a typical solar panel produced by the prevailing technology is 6.4 years. Furthermore, this value drops to 3.8 years under more favorable conditions. Moreover, since the major energy use reductions in terrestrial manufacturing have occurred in cell processing, this payback time directly illustrates the areas where major future energy reductions can be made -- silicon refinement, crystal growth, and panel building.

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    ABSTRACT: The time frame and the technical and economical requirements to make solar hydrogen a significant secondary energy carrier are Western Europe are discussed. The basic elements for the production of hydrogen are solar thermal and photovoltaic power plants and electrolyzers. Transporting hydrogen in pipelines (from Africa to Europe) makes it possible to decouple the demand from the time-dependent solar hydrogen generation. Results are presented for the material and land requirements, the energy pay-back times and the financial investment necessary. It is concluded that from a technical and financial point of view a sizeable amount of the energy demand of the year 2030 could be satisfied by solar hydrogen.
    No preview · Article · Dec 1986 · International Journal of Hydrogen Energy