Synergistic photothermal-thermoelectric-photovoltaic energy generation via a transparent spectral modulating solar module

Abstract

The efficiencies of photovoltaic (PV) and thermoelectric (TE) have been limited by the intrinsic materials properties. In solar applications, PV utilizes the shorter wavelength end of the solar spectrum while its longer portion (IR) can be photothermally (PT) converted to heat by special nano structures for TE electricity generation. We have developed spectral modulating nano systems made of Fe3O4@Cu2-XS nanoparticles and chlorophyllin capable of synergistic PT-TE-PV solar harvesting and energy generation. In this system, solar light is harvested through the transparent photothermal spectral modulator (TPSM) and segregated into different wavelengths: the IR is absorbed to photothermally heat up the TE hot end for the required thermoelectric temperature span; the UV/visible is directed to PV with reduced IR for significantly reduced heating, thus enhanced power conversion efficiency (PCE). Upon removal of IR, the PV surface temperature can be lowered from 86.9 ℃ to 65 ℃ after 120 min solar irradiation, resulting in PCE increase from 16.3 % (dropped from 25.1 % at 0 min) to 19. 4 %. A PT − TE − PV solar energy module (PTPSEM) is designed based on TPSM to synergistically generate energy by separately utilizing the full spectrum of solar light. Using the same solar light source, while generating electricity via PV, an additional 2.4 % is gained by a series of commercial thermoelectric generators (TEG), adding up to a total of 21. 8 % system efficiency which significantly exceeds the average efficiency of the commercial silicon PV panel used in this study. The spectral modulation mechanism through TPSM is identified based on the optical behaviors of chlorophyllin and Fe3O4@Cu2-XS. Also discussed is the design concept of PTPSEM.