Study On The Temperature Effect In Photovoltaic Conversion Process Of Solar Cells

Energy crisis has been a significant issue in economic development and concerned by many countries.Research about the renewable energy is essential to deal with the shortage of fossil fuels.Solar energy has been widely taken attention to by lots of researchers due to its advantages such as abundant storage and pollution-free.The research and application of solar energy have been promoted a lot nowadays.Solar cell is one of the main parts in photovoltaic applications.The performance of it is influenced not only by the materials and fabricationprocedure but also the working temperature.The temperature has a detrimental effect on the photovoltaic output of the solar cells.Consequently,conducting the research about temperature effect in solar cell applications is desirable to improving the photovoltaic performance of traditional solar cells.In this work,the crystalline silicon solar cell is used as the experimental object.The temperature effect in photovoltaic conversion process of solar cells has been investigated theoretically and experimentally.The main contents of this study are as follows.1.Microscale mechanism and temperature effect of related parameters in photovoltaic conversion process of solar cellsAn integrated physical model consisting of semiconductor physics and heat transfer process is established based on the photovoltaic effect mechanism in this study.In the simulation,amodel solar cell is discretized by using MATLAB.The carrier generation,transport and recombination processes are investigated through this new integrated physical model.In addition,this study investigated the effects of band gap energy,carrier mobility and lifetime on the carrier generation velocity and concentration.The influences of these parameters on thermalization,below band gap energy,recombination and Joule heat generations have been clarified.The proportions of different parameters in the whole temperature effect have been studied by comparing the effects of different parameters on the carrier concentrations and temperature distributions.Furthermore,the temperature effects of different parameters on the solar cellphotovoltaic performance have been explored.2.Temperature effect of solar cells under uniform conditionMono-crystalline silicon solar cell was employed as the experimental object in this study.A temperature effect measuring system has been established for investigating the variation of photovoltaic parameters along with temperature.The temperature effects of short-circuit current,open-circuit voltage,maximum output power,fill factor and the photovoltaic efficiency were illustrated.The temperature coefficient difference between the silicon solar cell and Ga As solar cell have been presented under different light intensities.3.The effect of external circuit series resistance on the photovoltaic performanceA series of designs about solar cell circuit were conducted to imitate measure conditons under different seriers resistances.The effect of external circuit series resistance on the photovoltaic performance was illustrated in this study.Moreover,the negative influence of contact resistance between solar cell and external circuit on the photovoltaic conversion was presented.4.Temperature effect of solar cells under non-uniform conditionA solar cell temperature and photovoltaic performance measuring system has been established based on the thermostat and laser beam in this study.A series of non-uniform temperature distributions formed by this system were used to imitate the practical working conditions in photovoltaic applications.The temperature effects of different non-uniform conditions on the photovoltaic performance have beeninvestigated.The temperature deterioration in the solar cell practical application and its influence on the photovoltaic performance have been further clarified.In addition,the deterioration degree of non-uniform condition under different light intensities was indicated through experimental study.5.Application solution of the solar cell temperature effectA novel integrated photovoltaic-thermoelectric(PV-TE)hybrid devicehas been designed and constructed for utilizing the redundant heat generated by the solar cell.The upper ceramic plate of thermoelectric device is removed for enhancing the heat transfer between the solar cell and thermoelectric device.For the purpose of avoiding the short circuit between PV and TE,an insulating layer was deposited on the back surface of the PV cell by the electron beamphysical vapor deposition(EB-PVD)technology.Furthermore,the heat transfer between PV and TE was optimized by applying the thermal grease.The comparison of output performance between the PV-TE device and pure PV cell has been illustrated under different light intensities and cooling conditions.The results showed that the PV-TE device could increase the output of PV cell and converse the heat generated by PV cell to electric power through TE device.Meanwhile,the detrimental temperature effect would be weakened.In addition,the effects of different thermal greases and insulating layer thickness on the whole integrated device photovoltaic performance have been fully studied.