Performance investigation of a hybrid photovoltaics and mid-temperature methanol thermochemistry system

Abstract

This work theoretically and experimentally presents a high-efficiency solar system which integrates photovoltaic cells and methanol thermal decomposition to make full use of the full-spectrum solar energy. In this optimized system, spectral beam splitting technology is used to split the solar spectrum into several wavebands. The spectrum suitable for photovoltaic conversion is directly converted to electricity using photovoltaic cells. The rest of the spectrum is converted into chemical energy of syngas (to be stored and converted to electricity on demand) via a mid-temperature solar-thermochemical process of methanol vapor decomposition reaction. A theoretical model is established and predicts that the electrical efficiency of the hybrid system could surpass 35%. The best system electrical efficiency, that we have experimentally demonstrated, was as high as 31.18% for a concentration ratio as low as 56 and a solar thermal temperature as low as 265 °C. The comparison to existing solar systems indicates that this proposed solar system has a great potential for efficient utilization of solar energy in large scale. This work paves the way to high-efficiency and full-spectrum utilization of solar energy.