Fabrication of a Microstructure-Enhanced Surface Area Solar Thermal Collector

Abstract

Solar energy is a renewable and sustainable energy source that has a promising potential for the rapidly growing energy demands across the world. Large scale power generation from the energy of the sun is well established utilizing both direct thermal energy conversion and conversion to electricity via photovoltaic processes. Solar thermal systems have been limited to macro systems, even though they operate at higher efficiency compared to photovoltaic systems. Solar energy harvesting requires the use of collector plates to capture incident radiation. The surface area exposed to incident radiation is critical in solar thermal energy harvesting. In this work, we have integrated micro technology processes and solar thermal energy to design and fabricate a micro solar thermal system for power generation. This work specifically examined surface area enhancement using MEMS-based techniques to maximize solar thermal absorption. Selective absorber coating and enhanced surface areas due to the incorporation of micro structures on the collector substrates were utilized. In this manner, an important component to an autonomous micro power supply is investigated. Advanced microfabrication and electrochemical deposition techniques were employed to generate a selective absorber surface with enhanced surface area on a silicon substrate. Microchannels were used to enhance the surface area on the substrate. The selective absorber coating consists of a bimetallic structure consisting of tin and nickel.