Optimal Design And Performance Analysis Of Photovoltaic Thermoelectric Coupling System

With the development of society,the rising energy demand cannot be fulfilled with the limited and depleting fossil fuels only.Development of renewable energies,particularly solar energy,is crucial and urgent for meeting energy needs.Photovoltaic technology,which directly converts solar energy into electricity based on the principle of photoelectric conversion,has been widely employed for its advantages such as pollution-free,and abundant reserves.However,PV cell is weak in utilizing the full solar spectrum.It can only absorb photon energy of the solar spectrum near the solar cell band-gap energy.The remaining energy is converted into thermal energy.Cooling PV cells is an urgent requirement due to the temperature growth may lead PV cell experience the performance loss and short the lifespan.Thermoelectric generator can convert heat directly into electric energy induced by the thermoelectric effect.In recent years,photovoltaic-thermoelectric coupling system has attracted much attention to enable full spectrum of solar radiation can be utilized by PV cells.Based on the working principle of the PV cell and TE de vice,the working temperature requirements are different.High temperature will reduce the PV cell performance,but it is conducive to improve TE de vice.Therefore,optimizing of interface heat transfer in photovoltaic-thermoelectric coupling system makes great significance.This paper manufactures photovoltaic-thermoelectric coupling device combined with monocrystalline silicon PV cell and bismuth telluride TE de vice,conducts on the optimization of the interface heat transfer of PV-TE coupling system.Mainly research work in this paper can be concluded as follows:（1）Effect of external circuit and loading resistance on photovoltaic-thermoelectric coupling system is studied.Then,the influence of cooling method and solar radiation on photovoltaic-thermoelectric coupling system has been explored through experimental research.Results show that,adding TE de vice can absorb the waste heat generated by PV cell,whic h suppresses the PV cell temperature rise and improve the output power of PV cell.TE device also contributes the additional energy output.Coupled with TE device,the performance of PV cell can be increased by 4.65%.（2）Thermal interface materials are used in photovoltaic-thermoelectric coupling device to enhance the utilization of solar energy.The relationship between the thermal conductivity and the performance of the photovoltaic-thermoelectric coupling system are carried out under different experimental conditions.Results indicate that,with thermal interface material,the power generation by PV cells increases at least 14%and the power generation by TE device increases at least 60%due to the decreasing thermal contact resistance.Applying thermal interface material enhances the heat transfer in photovoltaic-thermoelectric coupling device by filling the interface gap.（3）The integrated photovoltaic-thermoelectric coupling design is proposed to reduce the heat loss by removing the redundant parts of the coupling device.The back of PV cell is deposited Al₂O₃ insulating layer to protect electrical output of PV cell and TE de vice.The integrated photovoltaic-thermoelectric coupling design by simplifying the structure of coupling system,greatly improves the performance of PV cell and TE device.Furthermore,thermal interface materials are employed to enhance the heat transfer and thinner Al₂O₃ insulating layer is prepared by shortening the deposited time to significantly elevate the output of the coupling system.Results indicate that,with integrated photovoltaic-thermoelectric coupling design and subsequent optimization,the output of PV cell can be increased by 19.5%.The output of TE device elevates more significantly,up to 11.9 times.