Study On Dust Scattering Characteristics Of Photovoltaic Panels

Dust deposited on the surface of photovoltaic panels(PV panels)can cause problems such as reducing power generation efficiency,increasing local temperature,and corrosion of the modules.These problems can seriously affect the economic efficiency of photovoltaic power generation.Measuring the amount of dust deposited on the surface of PV panels is the key to improving the economic efficiency and extending the service life of PV panels.In order to address the shortcomings of existing measurement devices,a PV panel dust accumulation detection system that combines single-point scattering measurement with imaging detection is designed.In this article,the scattering effects of different particle sizes on light are investigated.Then the scattering effects of a sparse particle system and a dense particle system on the incident light are separately described according to the dust density of the dust layer.A scattering model of light irradiation on the surface of a dusty PV panel is established,and the relationship between the scattered light intensity on the surface of a dusty PV panel and then the dust density of the detection area is established.In this article,a measurement scheme based on the angle-resolved scattering principle is designed.And a scattered light detection device is built on the surface of the dust-accumulating PV panels.A modulated active light is used in the device to study the spatial distribution of scattered light intensity on the surface of dust-accumulating PV panels.And the relationship between the dust accumulation density and the scattered light intensity of PV panels is established.The intensity of scattered light is converted into a scattering rate by the ratio measurement method.And a lock-in amplifier is introduced to process the output signal of the detector so that the weak signals with a high signal-to-noise ratio can be extracted from the noisy background.In order to compensate for the defects in the scattering measurement that can’t characterize the dust distribution location on the PV panel surface,an imaging detection module is designed.First of all,the image of dust-accumulating PV panels is acquired by the module.Algorithms are used to correct the distortion of the image and remove the interference of metal grid lines on the surface of PV panels.Then the RGB three-channel OTSU algorithm is used to segment the image.The minimum outer rectangle is fitted to the segmented image to obtain the distribution location and coverage area of the dust on the PV panel surface.The scattering rate of dust accumulation on the surface of PV panels is measured at different detection azimuths.The experimental results show that the linearity of dust density and scattering rate is better and the dynamic range is larger when the detector is on the same side of the light source.The relationship between dust density and scattering rate is further investigated by irradiating laser sources with wavelengths of 405 nm,525 nm,and 635 nm on the surface of the dust-accumulated PV panels.The experiments show that when the dust accumulation density on the surface of the PV panel is small,the scattering rate on the surface of the PV panel increases linearly with the growth of the dust accumulation density,and the scattering rate of light with a wavelength of 405 nm is the highest.And as the dust accumulation density on the surface of the PV panel increases,the dust layer shifts from a sparse particle system to a dense particle system,and the growth trend of the scattering rate on the surface of the PV panel slows down gradually and finally tends to a certain value.At this time,the scattering rate of light with a wavelength of 635 nm is the highest.Based on the established correspondence between dust density and scattering rate,the scattered light intensity on the surface of PV panels is measured to characterize the dust density of PV panels and to obtain the information of dust distribution location and coverage area on the surface of PV panels by imaging detection.Combining the three factors of dust accumulation density,distribution location,and coverage area on the PV panel surface so that the relationship between dust accumulation density and power loss at the plant is established by the PV plants and a fast and accurate judgment basis is provided to assist in the decision-making process for the PV panel cleaning cycle.