Hybrid energy harvesting system to maximize power generation from solar energy

Concentrated photovoltaic (CPV) modules experience a reduction in the conversion efficiency with increasing in the cell temperature as a result of long wavelength solar irradiation which is not absorbed by the cell's band gap. Separation of long wavelength solar spectrum from the solar irradiation helps to fully utilize the solar irradiation as a part of the otherwise wasted long wavelength thermal energy can be converted into useful electricity by the other types of energy harvesting mechanisms. In order to enhance overall energy harvesting from the solar irradiation, a novel hybrid energy harvesting system based on separation of the solar irradiation and comprising a solar concentrator, CPV, beam splitter, cavity, Stirling engine and solar thermoelectric generators (STEGs) is considered in this study. The STEGs are, furthermore, used in the cavity to protect the Stirling engine from overheating. Coupled governing equations are created and developed to predict and investigate daily performance of the hybrid system including the conversion efficiency and electrical power. Engineering Equation Solver (EES) software is used to solve the governing equations and to evaluate of the model. Moreover, cost performance of the hybrid system and its energy harvester components is estimated. Aalborg, Denmark, was selected as the location for investigation of the model. The results of the analytical model are in a good agreement with experimental results and previous studies for the considered energy harvesting mechanisms. The results show an overall system conversion efficiency of 21.8% and a total electric power output of 45.4 kW at 455 suns during the peak solar irradiance hours. In this period, the STEG is able to produce 1.2 kW electrical power. The CPV and STEG have higher cost performance amongst the studied energy harvesters in the hybrid power generator system. The results, moreover, indicate that the considered hybrid system has high potential to play a significant role among future renewable technologies as a high-efficient hybrid energy harvester.