Numerical simulation to study the effect of spectral division of solar irradiance on the spectral splitting photovoltaic/thermal system

As a typical photo-thermal-electric multiphysics process, the energy transfer and conversion in spectral splitting photovoltaic/thermal (PV/T) systems are rather complex. For a better prediction of the system performance, a fully-coupled finite volume-discrete ordinates (FV-DO) radiation model for the numerical simulation of the PV/T system was developed. However, the previously proposed models still lacked detailed discussion for the spectrum division, to improve the criteria for the "spectrum mesh", this study applied the wavelet decomposition method and the piecewise constant fitting method for the spectrum division in the fully-coupled model and herein evaluated the initially introduced spectrum errors (the total radiation absolute error AE, root mean square error RMSE, and the correlation coefficient gamma). Then the influence of spectrum division on the PV/T system performances (the absorbed radiation, PV cell temperature, energy efficiency, and merit function) were comprehensively investigated. Eventually, the relations between initially introduced spectrum indexes and the absolute errors of performance indicators comparing with benchmark results were discussed. The result of 20 bands divided by the piecewise constant fitting method, which could achieve relative errors of PV temperature, energy efficiency from the benchmark by 0.046% and 0.840%, respectively, was recommended as a compromise between the accuracy and the increasing computing resources. RSME and gamma of the discrete spectrum can be used to initially estimate the accuracy of the performance of the spectral splitting PV/T system. (C) 2021 Elsevier Ltd. All rights reserved.