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Short-Term Solar Irradiance Forecasts Using Sky Images and Radiative Transfer Model
摘要： In this paper, we propose a novel forecast method which addresses the difficulty in short-term solar irradiance forecasting that arises due to rapidly evolving environmental factors over short time periods. This involves the forecasting of Global Horizontal Irradiance (GHI) that combines prediction sky images with a Radiative Transfer Model (RTM). The prediction images (up to 10 min ahead) are produced by a non-local optical flow method, which is used to calculate the cloud motion for each pixel, with consecutive sky images at 1 min intervals. The Direct Normal Irradiance (DNI) and the diffuse radiation intensity field under clear sky and overcast conditions obtained from the RTM are then mapped to the sky images. Through combining the cloud locations on the prediction image with the corresponding instance of image-based DNI and diffuse radiation intensity fields, the GHI can be quantitatively forecasted for time horizons of 1–10 min ahead. The solar forecasts are evaluated in terms of root mean square error (RMSE) and mean absolute error (MAE) in relation to in-situ measurements and compared to the performance of the persistence model. The results of our experiment show that GHI forecasts using the proposed method perform better than the persistence model.
关键词： radiative transfer model,Global Horizontal Irradiance (GHI),solar forecasting,sky imaging
更新于2025-09-23 15:21:01
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[IEEE 2018 IEEE 31st Canadian Conference on Electrical & Computer Engineering (CCECE) - Quebec City, QC (2018.5.13-2018.5.16)] 2018 IEEE Canadian Conference on Electrical & Computer Engineering (CCECE) - Solar Forecasting Using Remote Solar Monitoring Stations and Artificial Neural Networks
摘要： The need to accurately forecast available solar irradiance is a significant issue for the power industry and poses special challenges for utilities who serve customers in isolated regions where weather forecast data may not be abundant. This paper proposes a method to forecast two hour ahead solar irradiance levels at a site in Northwestern Alberta, Canada using real-time solar irradiance measured both locally and at remote monitoring stations. This paper makes use of an Artificial Neural Network (ANN) to forecast the solar irradiance levels and uses the genetic algorithm to determine the optimal array size and positioning of solar monitoring stations to obtain the most accurate forecast from the ANN. The findings of this paper are that it is possible to use as few as five remote monitoring stations to obtain a near-peak forecasting accuracy from the algorithm and that providing adequate geospatial separation of the remote monitoring sites around the target site is more desirable than clustering the sites in the strictly upwind directions.
关键词： GHI,remote sensing,solar,PV,isolated generation,forecasting,irradiance,artificial neural network
更新于2025-09-23 15:21:01
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Designing a Dual Axis Solar Tracking System for Maximum Power
摘要： The main purpose of this paper is to present a control system which will cause better alignment of Photo voltaic (PV) array with sun light and to harvest solar power. The proposed system changes its direction in two axis to trace the coordinate of sunlight by detecting the difference between position of sun and panel. Hardware testing of the proposed system is done for checking the system ability to track and follow the sunlight in an efficient way. Dual axis solar tracking system superiority over single axis solar tracking system is also presented.
关键词： Solar,Single axis,Irradiance,Tracker,DC motor,Dual axis
更新于2025-09-23 15:21:01
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Atmospheric response to the 20 March 2015 solar eclipse along the whole aerosol column by lidar measurements
摘要： Lidar measurements at 355, 532, and 1064 nm have been performed at Lecce (40.3°N, 18.1°E), in south-eastern Italy, to investigate for the first time the impact of the 20 March 2015 solar eclipse on both the planetary boundary layer (PBL) height and the aerosol optical and microphysical properties along the whole aerosol column. The partial solar eclipse lasted from 08:30 up to 10:47 UTC and reached the full phase at 09:37 UTC. The maximum percentage obscuration of the solar disk was 43.6%. The eclipse cooling effect was responsible at the full phase time (tF) for the downward solar irradiance decrease at the top of the atmosphere, at the surface, and within the atmosphere of 429.2 ± 0.6, 373 ± 25, and 56 ± 26 W m-2, respectively. The turbulent kinetic energy, the potential temperature flux, the sensible heat flux, the variance of air temperature, and the vertical wind speed at the surface revealed that the turbulence activity reached the maximum weakening at the time tF. The standard deviation (SD) technique has been applied to both the lidar range corrected signals (RCS) at 1064 nm and the linear volume depolarization ratio (δV) profiles at 355 nm to determine the time evolution of the shallow PBL height and the aloft aerosol layers. The SD technique applied to RCS and δV profiles revealed similar results within experimental uncertainties. The PBL height, which was equal to 380 ± 40 m above ground level (AGL) at the eclipse full phase (09:37 UTC), decreased up to 220 ± 20 m at 09:45 UTC because of the eclipse cooling effect, and then increased up to 320 ± 30 m at 10:17 UTC. The determined PBL height time evolution was in good agreement with the ones of the main turbulence parameters at the surface after tF. The vertical profiles of the aerosol backscatter coefficient (β), the δV at 355 nm, and the extinction-related ?ngstr?m exponent (?), calculated at the 355-1064 nm wavelength pair revealed a marked decrease of β, δV, and ? at the eclipse full phase, within the aloft aerosol layers. The abrupt β, δV, and ? decrease due to the aerosol concentration and type changes has mainly been associated with the decrease of the fine-mode particle contribution.
关键词： solar irradiance,Solar eclipse,lidar measurements,atmospheric aerosols,turbulence parameters,planetary boundary layer
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Experimental Study of the Spectral and Angular Solar Irradiance
摘要： We developed an experimental set-up and procedure to measure spectral and angular solar irradiance to accurately predict and optimize solar power plant performance. The set-up is comprised of a fiber coupled spectrometer mounted to a rotational stage which allows for 360? light capture. The lightweight and flexible design enables irradiance measurements at any location. Measurements were taken in Enschede, Netherlands and in Phoenix, AZ, USA. We find a strong location, dependence of spectro-angular irradiance on the surroundings and cloud coverage which needs to be considered when modelling and optimizing location dependent solar power plant output.
关键词： spectral albedo,Bifacial solar cells,spectral and angular irradiance,solar irradiance measurements
更新于2025-09-23 15:19:57
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Geometrical optimization for a photovoltaic installation equipped with flat reflectors based on plane of array estimations
摘要： In order to design, manage and optimize the performance of a photovoltaic (PV) installation and establish a precise power production estimation, irradiance on the plane of array (POA) in relation with the geometrical characteristics of the PV modules installation occupies a high importance. This study focuses on the development of an estimation model of the POA irradiance for a photovoltaic installation equipped with ?at re?ectors. The model includes solar irradiance components (global, direct and diffuse), geometrical parameters and geographical characteristics of the PV installation. Experimental validations have been performed with measurements taken at the SIRTA Observatory (48.7°N, 2.2°E) in Palaiseau, France, for the period starting from June 2017 to June 2018. Results show mean absolute errors (relative to the mean) of 6% and 7% for an installation without and with planar re?ector. Finally, we present several geometrical optimization strategies of the PV-re?ector installation relying on two major variables: the re?ector’s length (LR) compared to the length of the PV module (LPV) and the tilt angle adjustment frequency (monthly, seasonally, ?xed) of the system (for both PV and the re?ectors). The objective of such optimization is to discuss about a reasonable con?guration to achieve a maximum POA irradiance. Results show that the length of the mirrors highly affects the ef?ciency and performances of the PV-Re?ector system and the annual gain increased from 8.5% to 28.7% when going from LR = LPV/2 to LR = 2 (cid:1) LPV compared to a monthly-optimized installation without mirrors. As for the adjustment frequency, we show that a monthly-varied architecture is the most advantageous option with a 28.2 and 31.6% increasing in annual gain compared to a seasonal varied or ?xed ones, respectively.
关键词： ?at re?ectors,PV-re?ector system,plane of array irradiance,geometrical optimization,irradiance estimation
更新于2025-09-23 15:19:57
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Photovoltaic panels as shading resources for livestock
摘要： Based on our search, we believe that this is the first paper to evaluate the use of photovoltaic panels as shade resources for livestock. Photovoltaic panels can provide artificial shades to protect livestock against intense solar radiation while serving as a clean energy source, reducing CO2 emission, and providing an additional source of income to farmers. These benefits foster sustainable livestock farming practices. In this study, we (1) determined livestock shade preference for photovoltaic panels and the classical 80%-blockage cloth material, and (2) quantified the reduction in radiant heat load provided by these shade structures. To determine the shade preference, the behavior of five Corriedale lambs and six Corriedale ewes were observed in a paddock with two shade structures (one with photovoltaic panels and another with an 80%-blockage cloth). The following behavioral activities were determined using the instantaneous scan sampling method each 10-min from 07:00h to 17:00h: grazing, ruminating, idling, lying, standing, under the sun, under the shade from photovoltaic panels, and under the shade from cloth. To correlate animal behavior with environmental conditions and to quantify the reduction in radiant heat load provided by these shade structures, the following meteorological variables were recorded: solar radiation (total and short-wave), air temperature, relative humidity, wind speed, and black-globe temperature (in the shades and in the sun). We observed that the animals spent less than 1% of their time under the shade from cloth compared to 38% under the shade from photovoltaic panels and 61% exposed to the sun. Sheep preference for shade projected by photovoltaic panels might be explained by the reduced radiant heat load (approximately lower by 40 W m-2) compared to that from the cloth. When the intensity of solar radiation increased from 250 to 850 W m-2, the time the animals spent outside the shades decreased from 96.7 ± 3.6 % to 30.2 ± 6.3 %, which was coupled with a similar increase in the time spent in the shade from photovoltaic panels (from 13.0 ± 3.3 % to 69.3 ± 6.2 %). For the same increase in solar radiation, the energy generated (integrated over 5-min) by the photovoltaic panels increased from 38.8 ± 5.9 to 197.9 ± 3.8 kWh. Over a period of one year, an electric energy of 5.19 MWh (monthly average of 432.33 kWh) was generated and 2.77 tons of CO2 were not emitted to the atmosphere. In economic terms, the electric energy generated in one year was equivalent to a saving of $740.
关键词： photovoltaic panel,tropical conditions,livestock,shade,solar irradiance
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Improvement of Global Horizontal Irradiance Forecasts from Unified Model over the Korean Peninsula by Using Model Output Statistics
摘要： Solar irradiance was forecasted by the operational numerical weather prediction model in Korea Meteorological Administration. The quantitative evaluation was made against the in situ measurements at 37 ground observing stations. The relative mean bias error values are ranging from -6.9% to 39.9% and then grouped by K-means clustering. For each cluster, the model output statistics are employed to correct the model biases, resulting in the reduction of mean absolute error for global horizontal irradiance forecasts.
关键词： model output statistics,error metrics,numerical weather prediction,solar irradiance forecast
更新于2025-09-23 15:19:57
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[Laser Institute of America ILSC?? 2015: Proceedings of the International Laser Safety Conference - Albuquerque, New Mexico, USA (March 23a??26, 2015)] International Laser Safety Conference - The specular methodology for reflected laser hazard analyses
摘要： Reflection of a laser beam from a surface depends on the optical properties of the surface, and can have components that are diffuse (in all directions) or specular (in one direction). Hazard distances tend to be short and easily calculated for diffuse reflections. However, specular reflections have longer hazard distances and their calculation poses challenges due to the spatial and temporal characteristics of the reflected beam. We have developed and refined a methodology to calculate hazard distances from specular reflections. This methodology uses analytical expressions to determine the irradiance and exposure time of the reflected beam, from which hazard distances are calculated. The method accounts for the properties of the incident beam, the material reflecting properties, and the shape of the surface.
关键词： irradiance,specular reflections,laser hazard analyses,exposure time,hazard distances
更新于2025-09-23 15:19:57
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Linear-Gompertz Model-Based Regression of Photovoltaic Power Generation by Satellite Imagery-Based Solar Irradiance
摘要： A simple yet accurate photovoltaic (PV) performance curve as a function of satellite-based solar irradiation is necessary to develop a PV power forecasting model that can cover all of South Korea, where more than 35,000 PV power plants are currently in operation. In order to express the nonlinear power output of the PV module with respect to the hourly global horizontal irradiance derived from satellite images, this study employed the Gompertz model, which is composed of three parameters and the sigmoid equation. The nonphysical behavior of the Gompertz model within the low solar irradiation range was corrected by combining a linear equation with the same gradient at the conjoint point. The overall ?tness of Linear-Gompertz regression to the 242 PV power plants representing the country was R2 = 0.85 and nRMSE = 0.09. The Gompertz model coe?cients showed normal distributions and equivariance of standard deviations of less than 15% by year and by season. Therefore, it can be conjectured that the Linear-Gompertz model represents the whole country’s PV system performance curve. In addition, the Gompertz coe?cient C, which controls the growth rate of the curve, showed a strong correlation with the capacity factor, such that the regression equation for the capacity factor could be derived as a function of the three Gompertz model coe?cients with a ?tness of R2 = 0.88.
关键词： photovoltaic system performance,Gompertz model,power output prediction,satellite-derived global horizontal irradiance,numerical analysis
更新于2025-09-23 15:19:57