Study on the Influence of Atmospheric Environment on the Power Generation Performance of Photovoltaic Panel in Desertification Areas
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【Author in Chinese】 刘天胜；
【Author's Information】 宁夏大学， 凝聚态物理， 2020， 硕士
【Abstract】 Photovoltaic power generation has many advantages in many new green energy sources such as cleanness and no pollution,the most mature technology,simple device structure,application and popularization,etc.Desertification areas have abundant solar energy resources,strong illumination,low air humidity and other favorable environmental conditions,which provide unique conditions for the development of photovoltaic power stations.However,environmental conditions and their own performance also have some limiting factors on their power generation,such as photovoltaic panel temperature,incident irradiance and dust particles suspended in the air.Therefore,how to accurately predict the power generation efficiency of photovoltaic modules is a hot topic for many scholars in related fields in recent years.Good progress has been made in the prediction of incident irradiance,but the prediction model of photovoltaic cell temperature is still a research hotspot in this field.In this paper,the basic problems of dust deposition in photovoltaic power station,the influence mechanism of dust particles on photovoltaic panels and the temperature prediction model of photovoltaic panels are studied.The main tasks include:Firstly,the calculation of wind speed profile and dust settlement in photovoltaic power station is studied by combining field test with numerical modeling and analysis.The results show that:(1)the wind speed profile in photovoltaic panel array obeys the improved Prandtl model;(2)Based on the formula of dry dust deposition rate under rough surface condition,the dry dust deposition rate under different conditions is analyzed,and the horizontal flux of atmospheric dust deposition can be preliminarily predicted based on this formula.(3)The inclination angle of the photovoltaic panel will affect the distribution law of dust accumulation.With the increase of the inclination angle from 0 degree to 50 degree,the dust accumulation on the surface of the photovoltaic panel gradually shifts from the top to the bottom,and is relatively concentrated at the central axis of the panel at 30 degree,and the dust accumulation shows a change law of increasing first and then decreasing,and the dust accumulation is the smallest at 30 degree.Based on this,the conversion relationship between the dust deposition in horizontal plane and the dust deposition in inclined plane can be approximately established,thus providing a basis for the prediction of the dust deposition on the surface area of photovoltaic panels in photovoltaic arrays.Secondly,based on MIE scattering theory,the distribution law of electromagnetic field outside the particles under sunlight irradiation is studied.It is found that the deposited dust has a condensing and warming effect on photovoltaic panels,and this phenomenon weakens sharply along the incident direction with the increase of the radial distance to the particles,but this effect will increase with the increase of the ratio of particle size to incident wave wavelength.At the same time,combined with relevant theoretical analysis,we believe that it is possible to reverse the negative impact of dust accumulation on photovoltaic panels by designing a special photovoltaic panel structure.These results are of great significance for accurately understanding and effectively containing the negative impact of dust accumulation on photovoltaic systems.Finally,based on the measured data of Tengger Desert Photovoltaic Industrial Park in Zhongwei,Ningxia,a regression prediction model is established,which can quantitatively reflect the influence of solar radiation intensity,ambient temperature,wind speed and wind direction on photovoltaic panel temperature of desert photovoltaic power station.Therefore,combined with the equivalent circuit model of photovoltaic cells,the power output characteristics of desert photovoltaic modules under different environmental factors are discussed.Relevant numerical simulation results show that the accurate prediction of photovoltaic module output power must take into account solar radiation intensity,air temperature,wind speed,wind direction,sediment quality and transparency.With the decrease of the transparency of sediment particles,the maximum output power of photovoltaic modules decreases to varying degrees.At the same time,we found that for photovoltaic glass plates with the same light transmittance and different types of particles deposited on the surface,the sediment mass density ratio increases exponentially with the increase of the particle transparency ratio.This result can explain the phenomenon that the mass distribution density of deposits on dusty photovoltaic glass with the same light transmittance differs by several orders of magnitude in many literatures.In this paper,the prediction of dust accumulation in photovoltaic power stations and the influence mechanism of dust accumulation on photovoltaic systems are preliminarily discussed,and a temperature prediction model of photovoltaic modules suitable for desertification conditions is given,which is helpful to establish a more effective prediction model of photovoltaic power generation in desert environment.