Study On Radiative Heat Dissipation Structure For Solar Cells

Photovoltaic conversion is one of the most common solar energy utilization and solar cells are the core component of the photovoltaic conversion.Most of the absorbed solar energy is converted into heat since the photovoltaic conversion efficiency of solar cells is limited,which increases the temperature of solar cells and limits the photovoltaic conversion efficiency consequently.Therefore,it is extremely important to reduce the operating temperature of solar cells.The conventional cooling methods mainly focus on active cooling,which requires extra energy-consμmption equipment,high cost,complicated installation and has low reliability.In recent years,radiative cooling of the solar cell draws more attention.It is a completely passive cooling method that does not need any other equipment or energy input but only the spectral selective radiator.In this paper,three periodic microstructures,including gratings,pyramids,and domes,based on the thermal radiation theory of solar cells are proposed,optically simulated and optimized.At the same time,periodic pyramid structure radiators are prepared and the corresponding performance is analyzed.The main work of this paper can be divided into the following four parts:1.A thermal analysis model of the solar cells’ radiative heat dissipation is established,the potential of the solar cell’ radiative heat dissipation is preliminarily evaluated and the corresponding parametric analysis is conducted.The results show that without affecting the effective absorption of solar energy,increasing the mid-infrared emissivity of solar cells is beneficial to cells’ radiative dissipation.2.Silicon dioxide and PDMS are selected as materials of radiators,three periodic microstructures,including gratings,pyramids,and domes,are designed,and the spectral simulation and optimization are performed using Rigorous Coupled Wave Analysis.The results show that the optimal duty ratios of the three microstructures are 0.2,0.9,and 0.9and the optimal periods are 5,10,and 5 μm,respectively.Meanwhile,the pyramid structure based on PDMS has the best spectral characteristics,its emissivity is close to 1 in the mid-infrared region,and the absorptivity is close to 0 in the visible and NIR region.3.The periodic pyramid PDMS radiator is fabricated by photolithography,wet etching and microstructure transfer,and its morphology and spectral characterization are also performed.The results show that the pyramid structure is integral,the period is stable,and its transmittance in the wavelength range of 0.3–1.1 μm and the emissivity in the wavelength range of 1.1–4.0 μm are both close to 1.4.An outdoor experimental device is set up.The prepared periodic pyramid PDMS radiator with the encapsulated polycrystalline silicon solar cell is combined and the experimental test is conducted under the outdoor condition,with the assistance of I-V curve testing.The results show that the radiative heat dissipation capability of solar cells is improved after adding the radiator on the encapsulated polycrystalline silicon solar cell,and the temperature can be reduced by approximately 2°C-3°C.Besides,the I-V curve shows that the solar absorption of solar cells is unchanged when the radiator is added.The above results prove that the fabricated periodic pyramid PDMS radiator has a passive cooling effect for solar cells.