Research On A Thin Photovoltaic/Thermal Absorber Based On Thin Film Cells And Flexible Capillary Networks

The demand for energy in outdoor work and survival is increasing,and there are some significant shortcomings in the existing conventional energy supply methods,such as the need to carry a large amount of fuel for conventional generators and heavy weight of cells.Photovoltaic/thermal(PV/T)technology that comprehensively utilizes solar energy for on-site power and heating has become an important technical approach to addressing outdoor operation and survival functionalities.However,existing PV/thermal collectors are mostly rigid in structure and not portable,and there is further potential to reduce their weight.In order to reduce the weight of the PV/T system,improve its portability,this paper proposes a lightweight and thin PV/T absorber based on the combination of thin-film solar cells and flexible heat exchangers.The absorber was studied by all-day experiment,variable parameter experiment,improved experiment and parametric theoretical analysis.The main research contents are as follows:1.A thin-film photovoltaic/thermal absorber was designed and fabricated based on thin-film battery and flexible heat exchanger.Through a comparison,analysis,and summary of various battery performance parameters,copper indium gallium selenide(CIGS)batteries were selected as photovoltaic components,and plastic capillary networks were chosen as the heat collecting device.2.Performance testing of the lightweight PV/T system under summer conditions was conducted,and the performance of the absorber in summer was studied: the surface temperature of the absorber followed a distribution pattern of high in the middle and low on both ends,and the temperature variation of the heat collecting plate was consistent with that of the battery surface temperature;the all-day average thermal efficiency and electrical efficiency were 23.97% and10.75%,respectively;the capillary network water-cooling channel structure effectively reduced the photovoltaic component temperature(10.79℃),increased the output power(10.24W),and improved the overall energy utilization efficiency(14.67%).3.Performance testing of the lightweight PV/T system under winter conditions was conducted,and the energy collection performance of the absorber in winter was studied: the all-day average thermal efficiency and electrical efficiency were 31.39% and 9.75%,respectively.The energy collection efficiency of the absorber decreased with an increase in the inlet water temperature and increased with an increase in water flow rate.4.Feasibility testing of bubble film to improve the energy collection performance of the lightweight PV/T system and all-day performance testing demonstrated that bubble film has some feasibility in improving the thermal efficiency of the absorber: After adding bubble film,the thermal efficiency of the absorber increased by 11.72%,and the electrical efficiency decreased by 2.38%.During the testing period when the wind speed was not less than 7m/s,the all-day heat collection and electricity collection were 1.57 MJ and 0.26 MJ,respectively,and the thermal efficiency and electrical efficiency were 24.51% and 4.1%,respectively.5.A comparative analysis between the lightweight PV/T absorber proposed in this paper and existing rigid PV/T collectors indicates that this lightweight absorber has the characteristics of high efficiency(average electrical efficiency of 10.75%),high power density(66.20W/kg),and a lightweight and thin design(unit area weight of 3.85 kg and thickness of 4cm).However,there are disadvantages with a relatively low thermal efficiency and a performance that is highly influenced by environmental factors,which can be improved by reducing the contact thermal resistance between the capillary network and the photovoltaic panel,using rectangular collecting tubes and adding a transparent insulation layer to the battery surface,as well as selecting coating materials.6.The validation of experimental data with the theoretical model indicates that the established theoretical model can be used to analyze the performance of the lightweight PV/T system.Through the theoretical analysis,it was found that under fixed parameter settings,as the solar irradiance and ambient temperature increase,the thermal efficiency increases,while the electrical efficiency decreases.Increasing inlet water temperature leads to a decrease in both thermal and electrical efficiency.However,as wind speed increases,the thermal efficiency decreases while the electrical efficiency increases.In summary,this paper develops and designs a portable energy collection equipment with high efficiency,high power density and light weight,which provides a new idea for the design of outdoor energy equipment.