Performance study of photovoltaic-thermochemical hybrid system with Cassegrain concentrator and spectral splitting integration

Given the cascade utilization of photon energy, concentrating spectral beam splitting hybrid conversion technology is one of the state-of-the-art solar energy harvesting schemes. In this paper, a novel photovoltaic-thermochemical hybrid system based on a Cassegrain concentrator is proposed for ameliorating optical efficiency and thermochemical conversion under spectral splitting. On this basis, solar energy penetration is improved by concentrating optimization and reactant flow regulation. A specially developed splitter is used to allocate different radiation bands, allowing for the thermochemical storage of photovoltaic loss at mid/low temperatures. The mathematical method covering ray tracing, parameter optimization, solar multi-effect conversion process, and evaluation is constructed and verified, by which the optical characteristics, thermodynamic regulation, and economic feasibility are quantitatively investigated. The results show that the optical efficiency of 79.2% can be obtained by multi-objective optimization considering the uniformity of energy flux and the deviation of ray incidence angle for the first time. With the assistance of the reactant flow strategy, the hybrid system has a solar-product conversion efficiency of more than 36.4% and a stable exergy conversion capacity under different irradiance conditions. Moreover, the system demonstrates a potential investment return and a controllable levelised cost of electricity. In summary, the research results will contribute to the feasibility of full-spectrum solar absorption and the applicability of dish concentrators in distributed scenarios.