Power spectral shaping for hydrogen production from silicon based hybrid thermo-photovoltaic water electrolysis

Abstract

Solar hydrogen is a promising source for sustainable energy. This work presents an effective sunlight spectral management for hydrogen production from hybrid thermo-photovoltaic (TPV) water electrolysis based on optimal power spectral splitting of the concentrated sunlight. In the proposed power spectral shaping scheme sunlight photons are split at every wavelength below the cutoff wavelength of the used photocell by an engineered splitter with optimal reflectivity spectra R(λ) which maximizes the solar-to-hydrogen production. It was shown that the proposed power spectral shaping scheme is more effective by 18% than the wavelength selectivity spectral splitting scheme that was handled in our previous work; also the proposed scheme predicts higher solar-to-hydrogen conversion by 200% compared to what was predicted by other researchers who works on optimized solar hydrogen systems. For instance, it was found that employing efficiencies of 0.7, 0.8 and 0.7 for the concentrating optics, thermal convertor and the electrolysis cell, respectively, about 27% of the sunlight could be stored as hydrogen fuel with the optimal power spectral shaping scheme, and about 23% with the optimal wavelength selectivity scheme; whereas, efficiency predictions for an optimized system by other researchers was less than 13%.