Experimental Study On Hydrogen Production From Photovoltaic Photothermal Coupled PEM Electrolytic

Developing green electricity such as photovoltaics and wind power is an important direction for improving China’s energy structure and achieving low-carbon sustainable development.Hydrogen energy has advantages in solving the storage and reuse of photovoltaics and wind power.The photovoltaic photothermal hydrogen production system is increasingly receiving attention,and the reasonable configuration of photovoltaic,photothermal,and hydrogen production equipment is particularly important for efficient hydrogen production and improving the utilization rate of solar energy.Based on PEM hydrogen production technology,the operation mode and stability of photovoltaic photothermal hydrogen production were studied.The operation mode and influencing factors of the photovoltaic photothermal coupled PEM hydrogen production system(PV/T-PEM)were studied using theoretical analysis,mathematical modeling,simulation,and experimental analysis methods.Based on the principles of PEM hydrogen production,photovoltaic and control,simulation models of photovoltaic hydrogen production systems with different coupling systems were established for photovoltaic cells,electrolytic cells,batteries,MPPT control,and corresponding transformation circuits and controllers.The effects of solar irradiance and operating temperature on the I-U and P-U curves of photovoltaic cells were analyzed through modeling and simulation.The effects of voltage,current density,and water temperature on the characteristic curves of PEM electrolytic cells were analyzed.Through the simulation model of photovoltaic hydrogen production system,the operating characteristics of direct coupled system and indirect coupled system were studied.The results showed that direct coupled system cannot stably produce hydrogen,and the hydrogen production speed will fluctuate greatly due to lighting conditions.The system is simple but not conducive to stable operation of the system;Indirect coupling systems can stabilize hydrogen production,which is less affected by climate change and is conducive to achieving stable hydrogen production.However,the system is complex.Based on the simulation results,a validation experimental system for photovoltaic panels and electrolytic cells was established.The reliability of the simulation model was verified by comparing the simulation and experimental data.We have built PV/T-PEM experimental systems with different coupling methods and conducted experimental studies on the operational stability of direct and indirect coupling systems.The experimental results indicate that the hydrogen production speed of a directly coupled photovoltaic hydrogen production system will vary regularly with solar irradiance.However,the high or low output voltage of photovoltaic modules affects the normal operation of PEM hydrogen production,and the stability of hydrogen production is poor;Indirect coupling can effectively suppress the instability of the output voltage of photovoltaic modules,and the system can stably and continuously produce hydrogen and maintain stable hydrogen production for a period of time after disconnecting the photovoltaic modules;The photothermal system can ensure that the electrolyte(pure water)operates at higher temperatures and improve the hydrogen production speed of the system.Through simulation and experimental analysis,it is shown that although the PV/T-PEM hydrogen production system is indirectly coupled,its good system stability is more suitable for practical applications.