Analysis of the solar spectrum allocation in a spectral-splitting photovoltaic-thermochemical hybrid system

•Spectrum is split and allocated to photovoltaic and thermochemical conversions.•Spectrum allocation in the photovoltaic-thermochemical system has been studied.•Allocating a wider band to photovoltaic cells is beneficial to solar conversion.•Solar-to-electric efficiency reaches 21.9% with the cutoff wavelength of 850 nm. The solar spectrum allocation of a spectral-splitting photovoltaic-thermochemical hybrid system is investigated. In the proposed photovoltaic-thermochemical hybrid system, the spectral band between 400 nm and the cutoff wavelength λS is allocated to photovoltaic cells for power generation, while the rest of the solar spectrum is used for the thermochemical reaction of methanol decomposition. The effect of spectral band allocation on the photovoltaic and thermochemical conversions is analyzed, and the optimal spectral split is determined for improving the overall solar energy conversion. The calculation shows that increasing the solar energy allocated to photovoltaic cells is conducive to the solar energy conversion. The experimental results show that when the cutoff wavelength λS increases to 850 nm, the net solar power of the system reaches 1006.0 W, and the solar-to-electricity efficiency is improved to 20.3% at the solar irradiance of 610 W/m2. The research findings provide guidance for the splitting and allocation of the solar spectrum in a photovoltaic-thermochemical hybrid system.