Thermoradiative (TR) cell under negative illumination paves a new way for the traditional PV-TE system to generate electricity at night. By combining PV/TR cell with TEG devices, the present work proposes a framework to analyze the possibility of electricity generation through the PV/TR-TE hybrid system under negative and positive illumination, benefiting from the thermoradiative effect. A theoretical calculation model is established for the variation of the perf. Thermoradiative (TR) cell under negative illumination paves a new way for the traditional PV-TE system to generate electricity at night. By combining PV/TR cell with TEG devices, the present work proposes a framework to analyze the possibility of electricity generation through the PV/TR-TE hybrid system under negative and positive illumination, benefiting from the thermoradiative effect. A theoretical calculation model is established for the variation of the performance of the hybrid system with the bandgap and the temperature. Based on the ideal thermodynamic limit hypothesis, the comprehensive analysis and prediction model of the hybrid system under positive illumination and negative illumination are established. The influence laws of the cell temperature and bandgap on the system efficiency and output power density are obtained, and the influence mechanism of non-ideal losses of important parameters is revealed. A three-dimensional real-time photon-thermal-electric coupling calculation model that can automatically recognize illumination patterns is established, and the power output of the hybrid system is calculated and evaluated by using 24 h real-time environmental data. This work sets attempt to establish the comprehensive and systematic models of PV-TEG under positive illumination and TR-TEG under negative illumination simultaneously, and quantitatively assesses the possibility of a new way for 24 h power generation.••••Traditional PV-TE system can generate electricity at night based on TR effect.••A comprehensive model for both positive and negative illumination is established.••The performance of the system under 24-hour real-time has been investigated.••Illumination patterns and calculation modes can be automatically identified.The scarcity of traditional fossil fuels and global population growth call for sustainable production of electricity. Among various renewable energy sources, solar energy is the one of the most promising and attractive energy supply source due to its inexhaustible and carbon friendly characteristics,,. Green electricity generation based on solar energy can take place in two separate pathways, one is photovoltaic (PV) device, the other is thermoelectric (TE) generator. These two pathways can operate independently using separate infrastructures, or they can be combined to achieve high solar energy utilization efficiency,,.Photovoltaic devices convert light into electricity directly. Photovoltaic effect refers to electron-hole pairs that generate when semiconductors irradiated by photons, creating potential differences,,. However, the intrinsic bandgaps Eg of semiconductor materials block the photoelectric conversion efficiency of PV devices, meaning that photons whose energy lower than Eg will completely ineffective for photovoltaic power generation. In addition, solar energy that cannot be converted into electricity by PV cells will be transferred to thermalization heat, which will increase the operating temperature of PV devices, inevitably leading to energy waste and low conversion efficiency,,. Tremendous progresses have been made to increase the photon m. In this work, we consider a generic hybrid photovoltaic/thermoradiative-thermoelectric system (PV/TR-TE) as shown in Fig. 1(d). It is clarified that the term TR is nothing different from PV cell. Nevertheless, the TR cell is for nighttime operation (negative illumination) and PV cell is conceived to be implemented during the daytime (positive illumination) in this paper.The TR cell, operating under negative illumination, emits photons into cold space to drive electron-hole recombination, resulting output current and voltage. The resulting temperature drop in TR cell causes a temperature difference between the two sides of the connected TEG, which generates additional electricity and increases output power of the hybrid system. The PV cell is executed under positive illumination, as described above, the output electricity of the hybrid system will be contributed by both PV and TE components. All in all, PV-TEG operates under positive illumination and TR-TEG works under negative illumination, so as to continuously generate output electricity power, which is the working principle of the hybrid system studied in this paper.In order to describe the behavior of the PV/TR-TE hybrid system, and thus demonstrate the possibility and convenience of the system being able to generate electricity for 24 h, it may be necessary to base on the following common sense. In the case of positive illumination, the incident radiation on the PV cells is considered to be fixed and the maximum power corresponds exactly to the maximum efficiency point (MEP), known as the maximum power point (MPP). In the case of negative illumination, however, the thermal radiating object is the cell itself, and the output power varies with the cell temperature (Tc), indicating the non-coincidence of the maximum efficiency and the efficiency at MPP,,,,. Fig. 3 shows how the efficiency and power density of the TR cell change with voltage when Eg = 0.1 eV, Ta = 300 K, and Tc = 1000 K. In the figure, the horizontal coordinate represents the voltage, the left vertical axis is the efficiency, and the right vertical axis denotes the power density. The left and right axes correspond to the meaning of the solid blue line and the dashed purple line, respectively. For 0.1 eV TR cell, it can be seen that the power density increases first and then decreases with the increase of voltage, reaching its maximum at −0.082 V. Such trend also applies to the efficiency, but the efficiency reaches its maximum at a voltage of −0.315 V. The maximum efficiency point MEP is represented by a red triangle on the efficiency curve, and the maximum power point MPP is represented by a red d.
