Modeling of solar thermal selective surfaces and thermoelectric generators

Abstract

A thermoelectric generator is a solid-state device that converts a heat flux into electrical power via the Seebeck effect. When a thermoelectric generator is inserted between a solar-absorbing surface and a heat sink, a solar thermoelectric generator is created which converts sunlight into electrical power. This thesis describes the design and optimization of solar thermoelectric generators, with a focus on systems with high optical concentration which utilize multiple material systems to maximize efficiency over a large temperature difference. Both single-stage and cascaded (multi-stage) generators are considered, over an optical concentration range of 0.1 to 1000X. It is shown that for high-concentration Bi₂Te₃/skutterudite solar thermoelectric generators, conversion efficiencies of 13% are possible with current thermoelectric materials and selective surfaces. Better selective surfaces are needed to improve the efficiency of solar thermoelectric generators. In this thesis, ideal selective surfaces for solar thermoelectric generators are characterized. Non-ideal selective surfaces are also characterized, with emphasis on how the non-idealities affect the solar thernoelectric gencrator performance. Finally. the efficiency limit for solar thermoclectric generators with non-directional absorbers is presented.