In order to evaluate the energy required for the production of solar power plant components, either photovoltaic or solar dynamic, a detailed investigation was necessary. This investigation included various types of solar cells like amorphous and monocrystalline silicon, gallium arsenide, multi-layer cells and also their industrial production processes today and perspectives for the mid-term future. Because most of the available data is related to terrestrial application, the different optimization criteria (cost and efficiency for earth application and specific mass for space application) and their consequences on the production had to be taken into account. Another factor which had to be considered is the energy required to install a solar power satellite in orbit, i.e. mainly the energy needed for the launch of the components including the energy required for the production of the (expendable) launcher and its propellants. Accumulated Energy Consumption Energetics Analysis of a SPS The total energy required to make a SPS operational can be divided into four major groups: • fabrication of the SPS components • transportation into low Earth orbit (LEO) • integration of the components in LEO and installation of the SPS in its final position • fabrication and installation of the required Earth infrastructure Maintenance and replacement of components is a fifth factor in the energy balance. A SPS consists of: • a power conversion subsystem, either photovoltaic or solar dynamic, converting solar radiation into electricity • a transmission subsystem transforming electricity into either a laser or microwave beam focused on the receiving station on Earth. • an auxiliary subsystem providing attitude and orbit control (AOCS), communication and data link to Earth etc. • depending on the design orbit an energy storage subsystem might become necessary • required space infrastructure, including maintenance equipment, habitats etc. Related to the final power output the power conversion subsystem is the part which requires the most energy for its production. Its size is directly proportional to the
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