Solar radiation is an important parameter in the fields of computer modeling,engineering technology and energy development.This paper evaluated the ability of three machine learning models,i.e.,Extreme Gradient Boosti...Solar radiation is an important parameter in the fields of computer modeling,engineering technology and energy development.This paper evaluated the ability of three machine learning models,i.e.,Extreme Gradient Boosting(XGBoost),Support Vector Machine(SVM)and Multivariate Adaptive Regression Splines(MARS),to estimate the daily diffuse solar radiation(Rd).The regular meteorological data of 1966-2015 at five stations in China were taken as the input parameters(including mean average temperature(Ta),theoretical sunshine duration(N),actual sunshine duration(n),daily average air relative humidity(RH),and extra-terrestrial solar radiation(Ra)).And their estimation accuracies were subjected to comparative analysis.The three models were first trained using meteorological data from 1966 to 2000.Then,the 2001-2015 data was used to test the trained machine learning model.The results show that the XGBoost had better accuracy than the other two models in coefficient of determination(R2),root mean square error(RMSE),mean bias error(MBE)and normalized root mean square error(NRMSE).The MARS performed better in the training phase than the testing phase,but became less accurate in the testing phase,with the R2 value falling by 2.7-16.9%on average.By contrast,the R2 values of SVM and XGBoost increased by 2.9-12.2%and 1.9-14.3%,respectively.Despite trailing slightly behind the SVM at the Beijing station,the XGBoost showed good performance at the rest of the stations in the two phases.In the training phase,the accuracy growth is small but observable.In addition,the XGBoost had a slightly lower RMSE than the SVM,a signal of its edge in stability.Therefore,the three machine learning models can estimate the daily Rd based on local inputs and the XGBoost stands out for its excellent performance and stability.展开更多
The main objective of this paper is to predict the diffuse solar energy on a horizontal surface by using data of global solar energy (H) and diffuse solar energy (H<sub>d</sub>) at different selected geogr...The main objective of this paper is to predict the diffuse solar energy on a horizontal surface by using data of global solar energy (H) and diffuse solar energy (H<sub>d</sub>) at different selected geographical locations in Saudi Arabia during the period time from 1980 to 2019. The low values of the root mean square error RMSE for all correlations indicated a good agreement between the measured and calculated values of H<sub>d</sub>. The negative values of mean percentage error MPE % for all models show that for all locations, the proposed correlations slightly overestimate H<sub>d</sub>, and the absolute values of MPE never reach 1.35%. The first, second and third order correlations between the diffuse solar fraction H<sub>d</sub>/H and the clearness index K<sub>t</sub> and between the diffuse transmittance H<sub>d</sub>/H<sub>0</sub> and the sunshine hours have been proposed for the selected locations using the method of regression analysis. The differences between the measured and calculated values of H<sub>d</sub> show that a first order correlation between H<sub>d</sub>/H and K<sub>t</sub> can be used for estimating H<sub>d</sub> at the present locations with good accuracy. However, second order correlations between Hd/H or H<sub>d</sub>/H<sub>0</sub> and S/S<sub>o</sub> are recommended for estimating H<sub>d</sub> at these locations. The average annual differences between measured and calculated values of diffuse solar energy H<sub>d</sub> on horizontal at selected sites in the present research are discussed.展开更多
Photoluminescence（PL） measurements are carried out to investigate the degradation of GaInP top cell and GaAs middle cell for GaInP/GaAs/Ge triple-junction solar cells irradiated with 1.0, 1.8 and 11.5 MeV electrons ...Photoluminescence（PL） measurements are carried out to investigate the degradation of GaInP top cell and GaAs middle cell for GaInP/GaAs/Ge triple-junction solar cells irradiated with 1.0, 1.8 and 11.5 MeV electrons with fluences ranging up to 3 × 10^15, 1 × 10^15 and 3 × 10^14 cm^-2, respectively. The degradation rates of PL intensity increase with the electron fluence and energy. Furthermore, the damage coefficient of minority carrier diffusion length is estimated by the PL radiative efficiency. The damage coefficient increases with the electron energy. The relation of damage coefficient to electron energy is discussed with the non-ionizing energy loss（NIEL）, which shows a quadratic dependence between damage coefficient and NIEL.展开更多
An analytical solution to the three-dimensional telegraph equation is presented. This equation has recently received some attention but so far the treatment has been one-dimensional. By using the structural similarity...An analytical solution to the three-dimensional telegraph equation is presented. This equation has recently received some attention but so far the treatment has been one-dimensional. By using the structural similarity to the Klein-Gordon equation, the telegraph equation can be solved in closed form. Illustrative examples are used to discuss the qualitative differences from the diffusion solution. A comparison with a numerical test-particle simulation reveals that some features of an intensity profile can be better explained using the telegraph approach.展开更多
Globally, solar energy is expected to play a significant role in the changing face of energy economies in the near future. However, the variability of this resource has been the main barrier for solar energy developme...Globally, solar energy is expected to play a significant role in the changing face of energy economies in the near future. However, the variability of this resource has been the main barrier for solar energy development in most locations around the world. This paper investigated the distribution and variability of solar radiation using the a 10-year （2006 to 2015） data collected at Sorhs meteor- ological station located at latitude 59° 39＇ N and longitude 10° 47＇E, about 93.3 m above sea level （about 30 km from Oslo）, in south-eastern part of Norway. It is found that on annual basis, the total number of days with a global solar radiation of less than 1 kWh/（m2.d） is 120 days while the total number of days with an expected global solar radiation greater than 3 kWh/（m2.d） is 156 days （42.74%） per year. The potential energy output from a horizontally placed solar collector in these 156 days is approximately 75% of the estimated annual energy output. In addition, it is found that the inter-annual coefficient of variation of the global solar radiation is 4.28%, while that of diffuse radiation is 4.96%.展开更多
SiNx/SiOx passivation and double side P-diffusion gettering treatment have been used for the fabrication of c-Si solar cells. The solar cells fabricated have high open circuit voltage and short circuit current after t...SiNx/SiOx passivation and double side P-diffusion gettering treatment have been used for the fabrication of c-Si solar cells. The solar cells fabricated have high open circuit voltage and short circuit current after the double P-diffusion treatment. In addition to better surface passivation effect, SiNx/SiOx layer has lower reflectivity in long wavelength range than conventional SiNx film. As a consequence, such solar cells exhibit higher conversion efficiency and better internal quantum efficiency, compared with conventional c-Si solar cells.展开更多
The power generation of bifacial photovoltaic modules is greatly related to the diffuse solar radiation component received by the rear side,but radiation component data are scarce in China,where bifacial solar market ...The power generation of bifacial photovoltaic modules is greatly related to the diffuse solar radiation component received by the rear side,but radiation component data are scarce in China,where bifacial solar market is large.Radiation components can be estimated from satellite data,but sufficient ground truth data are needed for calibrating empirical methods or training machine learning methods.In this work,a data-augmented machine learning method was proposed to estimate radiation components.Instead of using observed ground truth,far more abundant radiation component data derived from sunshine duration measured at 2,453 routine weather stations in China were used to augment samples for training a machine-learning-based model.The inputs of the model include solar radiation(either from ground observation or satellite remote sensing)and surface meteorological data.Independent validation of the model at Chinese stations and globally distributed stations demonstrates its effectiveness and generality.Using a state-of-the-art satellite product of solar radiation as input,the model is applied to construct a satellite-based radiation component dataset over China.The new dataset not only outperforms mainstream radiation component datasets,but also has significantly higher accuracy than satellite-based datasets derived from other machine learning methods trained with limited observations,indicating the superiority of our data-augmented method.In principle,this model can be applied on the global scale without additional training with local data.展开更多
An accurate and operational bidirectional reflectance distribution function （BDRF） canopy model is the basis of quantitative vegetation remote sensing. The canopy reflectance should be approximated as the sum of the...An accurate and operational bidirectional reflectance distribution function （BDRF） canopy model is the basis of quantitative vegetation remote sensing. The canopy reflectance should be approximated as the sum of the single scattering reflectance arising from the sun, pl, and the multiple scattering reflectance arising from the canopy, fin, as their directional characteristics are dramatically different. Based on the existing BRDF model, we obtain a new analytical expression of ρ1 and ρm in this paper, which is suitable for different illumination conditions and different vegetation canopies. According to the geometrical optic model at the leaf scale, the anisotropy of ρ1 can be ascribed to the geometry of the object, sun and the sensor, multiple scale clumping, and the fraction of direct solar radiation and diffuse sky radiation. Then, we parameterize the area ratios of four components： the sunlit foliage, sunlit ground, shadow foliage and shadow ground based on a Poisson distribution, and develop a new approximate analytical single scattering reflectance model. Assuming G=0.5, a recollision probability theory based scattering model is developed which considers the effects of diffuse sky radiation, scattering inside the canopy and rebounds between the canopy and soil. Validation using ground measurements of maize and black spruce forest proves the reliability of the model.展开更多
Environments do not exist in isolation.Their main components in greenhouse systems are plants.Without consideration of plants,analysis of greenhouse environments and environmental control of greenhouses can be accompl...Environments do not exist in isolation.Their main components in greenhouse systems are plants.Without consideration of plants,analysis of greenhouse environments and environmental control of greenhouses can be accomplished,although it is not simple to achieve.Initial attempts were undertaken to analyze greenhouse environments and then reproduce them.Ventilation rate effects on plant photosynthesis in a growth chamber were reported in 1966.Computer simulations then became a main subject of research.The first dynamic computer simulation of a greenhouse environment including plants was published in 1971.According to innovations of computer technology,the use of minicomputers and microcomputers spread in many areas.By measuring the net photosynthesis of lettuce plants grown under artificial lighting,air temperature was optimized using a minicomputer with the hill-climbing method.The method was designated as the Speaking Plant Approach to environment control(SPA).After the author developed the first reported environmental control system in Japan,systems using microcomputers spread widely for greenhouse environmental control.Knowledge-based expert systems were tested for plant management.Also,a machine vision system was developed to detect critical moments for watering of muskmelon plants.The first feed-forward control method for greenhouses with a large heat mass was reported.Then space farming was tested in 1996 to assess gravity effects on plants.Energy-saving aspects such as solar sterilization,ground heat storage system,and storage using phase change material(PCM)have been reported.Defects of ordinary solarimeters were reported in 2008 along with an approach to estimate evapotranspiration in a greenhouse without the effect of so-called cosine law.Later,this technique was expanded to estimate photosynthesis of the plant canopy in a greenhouse using newly developed sensor units.展开更多
In the solar system, our Sun is Nature's most efficient particle accelerator. In large solar flares and fast coronal mass ejections(CMEs), protons and heavy ions can be accelerated to over ~GeV/nucleon. Large flar...In the solar system, our Sun is Nature's most efficient particle accelerator. In large solar flares and fast coronal mass ejections(CMEs), protons and heavy ions can be accelerated to over ~GeV/nucleon. Large flares and fast CMEs often occur together. However there are clues that different acceleration mechanisms exist in these two processes. In solar flares, particles are accelerated at magnetic reconnection sites and stochastic acceleration likely dominates. In comparison, at CME-driven shocks,diffusive shock acceleration dominates. Besides solar flares and CMEs, which are transient events, acceleration of particles has also been observed in other places in the solar system, including the solar wind termination shock, planetary bow shocks, and shocks bounding the Corotation Interaction Regions(CIRs). Understanding how particles are accelerated in these places has been a central topic of space physics. However, because observations of energetic particles are often made at spacecraft near the Earth,propagation of energetic particles in the solar wind smears out many distinct features of the acceleration process. The propagation of a charged particle in the solar wind closely relates to the turbulent electric field and magnetic field of the solar wind through particle-wave interaction. A correct interpretation of the observations therefore requires a thorough understanding of the solar wind turbulence. Conversely, one can deduce properties of the solar wind turbulence from energetic particle observations. In this article I briefly review some of the current state of knowledge of particle acceleration and transport in the inner heliosphere and discuss a few topics which may bear the key features to further understand the problem of particle acceleration and transport.展开更多
Diffuse solar radiation models play an extremely important role in solar photothermal utilization,resource assess-ment and energy consumption simulation,etc.The accuracy of these diffuse solar radiation models usually...Diffuse solar radiation models play an extremely important role in solar photothermal utilization,resource assess-ment and energy consumption simulation,etc.The accuracy of these diffuse solar radiation models usually need to be evaluated by various statistical parameters.Among these statistical parameters,the Global Performance In-dex(GPI)has been extensively employed in recent years because of its comprehensiveness and wide applicability.This paper takes five cities in China as representatives of 5 typical climate regions,and 12 solar scattered radia-tion models are fitted with the meteorological data of 5 cities.Based on the comparative analysis of the existing GPI calculation methods,this paper points out that there are some defects in the existing GPI,and modifies the existing GPI based on the comprehensive consideration of statistical parameters,normalization preprocessing of statistical parameters,unified evaluation direction of parameters,weight redistribution of statistical parameters,and adjustment of extreme coefficient.12 types of new GPI are established in this paper,and the performance of diffuse solar radiation models are compared based on these GPI.The rationality of GPI corrective measures is analyzed by means of the method reasonable index(MRI).The results show that the GPI calculation method(N10)which takes five corrective measures has the best performance,and the accuracy of the existing GPI can be improved by 13.33 to 65%.展开更多
In this work, a comprehensive model that takes the phenomenon of carrier thermionic-emission within the frame work of a diffusion theory of current conducting into account in the type Ⅱ hetero-junction Cd Te solar ce...In this work, a comprehensive model that takes the phenomenon of carrier thermionic-emission within the frame work of a diffusion theory of current conducting into account in the type Ⅱ hetero-junction Cd Te solar cell is developed. According to this model, it is found that the total current flowing through the Cd Te solar cell is limited by the thermionic process for very thin quasi-neutral regions and limited by the diffusion process for the reverse case. In future research of the Cd Te solar cell, such an approach may enable the determination of the boundary conditions for all doping profiles and computation of the conversion efficiency, etc.展开更多
基金supported by National Natural Science Foundation of China(51769010,51979133,51469010 and 51109102).
文摘Solar radiation is an important parameter in the fields of computer modeling,engineering technology and energy development.This paper evaluated the ability of three machine learning models,i.e.,Extreme Gradient Boosting(XGBoost),Support Vector Machine(SVM)and Multivariate Adaptive Regression Splines(MARS),to estimate the daily diffuse solar radiation(Rd).The regular meteorological data of 1966-2015 at five stations in China were taken as the input parameters(including mean average temperature(Ta),theoretical sunshine duration(N),actual sunshine duration(n),daily average air relative humidity(RH),and extra-terrestrial solar radiation(Ra)).And their estimation accuracies were subjected to comparative analysis.The three models were first trained using meteorological data from 1966 to 2000.Then,the 2001-2015 data was used to test the trained machine learning model.The results show that the XGBoost had better accuracy than the other two models in coefficient of determination(R2),root mean square error(RMSE),mean bias error(MBE)and normalized root mean square error(NRMSE).The MARS performed better in the training phase than the testing phase,but became less accurate in the testing phase,with the R2 value falling by 2.7-16.9%on average.By contrast,the R2 values of SVM and XGBoost increased by 2.9-12.2%and 1.9-14.3%,respectively.Despite trailing slightly behind the SVM at the Beijing station,the XGBoost showed good performance at the rest of the stations in the two phases.In the training phase,the accuracy growth is small but observable.In addition,the XGBoost had a slightly lower RMSE than the SVM,a signal of its edge in stability.Therefore,the three machine learning models can estimate the daily Rd based on local inputs and the XGBoost stands out for its excellent performance and stability.
文摘The main objective of this paper is to predict the diffuse solar energy on a horizontal surface by using data of global solar energy (H) and diffuse solar energy (H<sub>d</sub>) at different selected geographical locations in Saudi Arabia during the period time from 1980 to 2019. The low values of the root mean square error RMSE for all correlations indicated a good agreement between the measured and calculated values of H<sub>d</sub>. The negative values of mean percentage error MPE % for all models show that for all locations, the proposed correlations slightly overestimate H<sub>d</sub>, and the absolute values of MPE never reach 1.35%. The first, second and third order correlations between the diffuse solar fraction H<sub>d</sub>/H and the clearness index K<sub>t</sub> and between the diffuse transmittance H<sub>d</sub>/H<sub>0</sub> and the sunshine hours have been proposed for the selected locations using the method of regression analysis. The differences between the measured and calculated values of H<sub>d</sub> show that a first order correlation between H<sub>d</sub>/H and K<sub>t</sub> can be used for estimating H<sub>d</sub> at the present locations with good accuracy. However, second order correlations between Hd/H or H<sub>d</sub>/H<sub>0</sub> and S/S<sub>o</sub> are recommended for estimating H<sub>d</sub> at these locations. The average annual differences between measured and calculated values of diffuse solar energy H<sub>d</sub> on horizontal at selected sites in the present research are discussed.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11675020,11375028,11075018 and 10675023
文摘Photoluminescence（PL） measurements are carried out to investigate the degradation of GaInP top cell and GaAs middle cell for GaInP/GaAs/Ge triple-junction solar cells irradiated with 1.0, 1.8 and 11.5 MeV electrons with fluences ranging up to 3 × 10^15, 1 × 10^15 and 3 × 10^14 cm^-2, respectively. The degradation rates of PL intensity increase with the electron fluence and energy. Furthermore, the damage coefficient of minority carrier diffusion length is estimated by the PL radiative efficiency. The damage coefficient increases with the electron energy. The relation of damage coefficient to electron energy is discussed with the non-ionizing energy loss（NIEL）, which shows a quadratic dependence between damage coefficient and NIEL.
文摘An analytical solution to the three-dimensional telegraph equation is presented. This equation has recently received some attention but so far the treatment has been one-dimensional. By using the structural similarity to the Klein-Gordon equation, the telegraph equation can be solved in closed form. Illustrative examples are used to discuss the qualitative differences from the diffusion solution. A comparison with a numerical test-particle simulation reveals that some features of an intensity profile can be better explained using the telegraph approach.
文摘Globally, solar energy is expected to play a significant role in the changing face of energy economies in the near future. However, the variability of this resource has been the main barrier for solar energy development in most locations around the world. This paper investigated the distribution and variability of solar radiation using the a 10-year （2006 to 2015） data collected at Sorhs meteor- ological station located at latitude 59° 39＇ N and longitude 10° 47＇E, about 93.3 m above sea level （about 30 km from Oslo）, in south-eastern part of Norway. It is found that on annual basis, the total number of days with a global solar radiation of less than 1 kWh/（m2.d） is 120 days while the total number of days with an expected global solar radiation greater than 3 kWh/（m2.d） is 156 days （42.74%） per year. The potential energy output from a horizontally placed solar collector in these 156 days is approximately 75% of the estimated annual energy output. In addition, it is found that the inter-annual coefficient of variation of the global solar radiation is 4.28%, while that of diffuse radiation is 4.96%.
基金Project supported by the National Natural Science Foundation of China(Nos.61474104,61504131)
文摘SiNx/SiOx passivation and double side P-diffusion gettering treatment have been used for the fabrication of c-Si solar cells. The solar cells fabricated have high open circuit voltage and short circuit current after the double P-diffusion treatment. In addition to better surface passivation effect, SiNx/SiOx layer has lower reflectivity in long wavelength range than conventional SiNx film. As a consequence, such solar cells exhibit higher conversion efficiency and better internal quantum efficiency, compared with conventional c-Si solar cells.
基金supported by the Sustainable Development International Cooperation Program of National Science Found-ation of China(Grant No.42361144875)the National Natural Science Foundation of China(Grant No.42171360).
文摘The power generation of bifacial photovoltaic modules is greatly related to the diffuse solar radiation component received by the rear side,but radiation component data are scarce in China,where bifacial solar market is large.Radiation components can be estimated from satellite data,but sufficient ground truth data are needed for calibrating empirical methods or training machine learning methods.In this work,a data-augmented machine learning method was proposed to estimate radiation components.Instead of using observed ground truth,far more abundant radiation component data derived from sunshine duration measured at 2,453 routine weather stations in China were used to augment samples for training a machine-learning-based model.The inputs of the model include solar radiation(either from ground observation or satellite remote sensing)and surface meteorological data.Independent validation of the model at Chinese stations and globally distributed stations demonstrates its effectiveness and generality.Using a state-of-the-art satellite product of solar radiation as input,the model is applied to construct a satellite-based radiation component dataset over China.The new dataset not only outperforms mainstream radiation component datasets,but also has significantly higher accuracy than satellite-based datasets derived from other machine learning methods trained with limited observations,indicating the superiority of our data-augmented method.In principle,this model can be applied on the global scale without additional training with local data.
基金supported by the National Natural Science Foundation of China(Grant Nos.41271346,41571329&41230747)the Major State Basic Research Development Program of China(Grant No.2013CB733402)
文摘An accurate and operational bidirectional reflectance distribution function （BDRF） canopy model is the basis of quantitative vegetation remote sensing. The canopy reflectance should be approximated as the sum of the single scattering reflectance arising from the sun, pl, and the multiple scattering reflectance arising from the canopy, fin, as their directional characteristics are dramatically different. Based on the existing BRDF model, we obtain a new analytical expression of ρ1 and ρm in this paper, which is suitable for different illumination conditions and different vegetation canopies. According to the geometrical optic model at the leaf scale, the anisotropy of ρ1 can be ascribed to the geometry of the object, sun and the sensor, multiple scale clumping, and the fraction of direct solar radiation and diffuse sky radiation. Then, we parameterize the area ratios of four components： the sunlit foliage, sunlit ground, shadow foliage and shadow ground based on a Poisson distribution, and develop a new approximate analytical single scattering reflectance model. Assuming G=0.5, a recollision probability theory based scattering model is developed which considers the effects of diffuse sky radiation, scattering inside the canopy and rebounds between the canopy and soil. Validation using ground measurements of maize and black spruce forest proves the reliability of the model.
文摘Environments do not exist in isolation.Their main components in greenhouse systems are plants.Without consideration of plants,analysis of greenhouse environments and environmental control of greenhouses can be accomplished,although it is not simple to achieve.Initial attempts were undertaken to analyze greenhouse environments and then reproduce them.Ventilation rate effects on plant photosynthesis in a growth chamber were reported in 1966.Computer simulations then became a main subject of research.The first dynamic computer simulation of a greenhouse environment including plants was published in 1971.According to innovations of computer technology,the use of minicomputers and microcomputers spread in many areas.By measuring the net photosynthesis of lettuce plants grown under artificial lighting,air temperature was optimized using a minicomputer with the hill-climbing method.The method was designated as the Speaking Plant Approach to environment control(SPA).After the author developed the first reported environmental control system in Japan,systems using microcomputers spread widely for greenhouse environmental control.Knowledge-based expert systems were tested for plant management.Also,a machine vision system was developed to detect critical moments for watering of muskmelon plants.The first feed-forward control method for greenhouses with a large heat mass was reported.Then space farming was tested in 1996 to assess gravity effects on plants.Energy-saving aspects such as solar sterilization,ground heat storage system,and storage using phase change material(PCM)have been reported.Defects of ordinary solarimeters were reported in 2008 along with an approach to estimate evapotranspiration in a greenhouse without the effect of so-called cosine law.Later,this technique was expanded to estimate photosynthesis of the plant canopy in a greenhouse using newly developed sensor units.
基金supported in part by a vip professorship grant from the School of Geophysics and Information Technology, China University of Geosciences (Beijing)
文摘In the solar system, our Sun is Nature's most efficient particle accelerator. In large solar flares and fast coronal mass ejections(CMEs), protons and heavy ions can be accelerated to over ~GeV/nucleon. Large flares and fast CMEs often occur together. However there are clues that different acceleration mechanisms exist in these two processes. In solar flares, particles are accelerated at magnetic reconnection sites and stochastic acceleration likely dominates. In comparison, at CME-driven shocks,diffusive shock acceleration dominates. Besides solar flares and CMEs, which are transient events, acceleration of particles has also been observed in other places in the solar system, including the solar wind termination shock, planetary bow shocks, and shocks bounding the Corotation Interaction Regions(CIRs). Understanding how particles are accelerated in these places has been a central topic of space physics. However, because observations of energetic particles are often made at spacecraft near the Earth,propagation of energetic particles in the solar wind smears out many distinct features of the acceleration process. The propagation of a charged particle in the solar wind closely relates to the turbulent electric field and magnetic field of the solar wind through particle-wave interaction. A correct interpretation of the observations therefore requires a thorough understanding of the solar wind turbulence. Conversely, one can deduce properties of the solar wind turbulence from energetic particle observations. In this article I briefly review some of the current state of knowledge of particle acceleration and transport in the inner heliosphere and discuss a few topics which may bear the key features to further understand the problem of particle acceleration and transport.
基金This research has been supported by National Natural Science Foun-dation of China(Grant No.52178083)Anhui Province Key Labora-tory of Intelligent Building and Building Energy Saving,Anhui Jianzhu University(Grant No.IBES2020KF12)Open Project of State Key Laboratory of Clean Energy Utilization,Zhejiang University(Grant No.ZJUCEU2020024).
文摘Diffuse solar radiation models play an extremely important role in solar photothermal utilization,resource assess-ment and energy consumption simulation,etc.The accuracy of these diffuse solar radiation models usually need to be evaluated by various statistical parameters.Among these statistical parameters,the Global Performance In-dex(GPI)has been extensively employed in recent years because of its comprehensiveness and wide applicability.This paper takes five cities in China as representatives of 5 typical climate regions,and 12 solar scattered radia-tion models are fitted with the meteorological data of 5 cities.Based on the comparative analysis of the existing GPI calculation methods,this paper points out that there are some defects in the existing GPI,and modifies the existing GPI based on the comprehensive consideration of statistical parameters,normalization preprocessing of statistical parameters,unified evaluation direction of parameters,weight redistribution of statistical parameters,and adjustment of extreme coefficient.12 types of new GPI are established in this paper,and the performance of diffuse solar radiation models are compared based on these GPI.The rationality of GPI corrective measures is analyzed by means of the method reasonable index(MRI).The results show that the GPI calculation method(N10)which takes five corrective measures has the best performance,and the accuracy of the existing GPI can be improved by 13.33 to 65%.
文摘In this work, a comprehensive model that takes the phenomenon of carrier thermionic-emission within the frame work of a diffusion theory of current conducting into account in the type Ⅱ hetero-junction Cd Te solar cell is developed. According to this model, it is found that the total current flowing through the Cd Te solar cell is limited by the thermionic process for very thin quasi-neutral regions and limited by the diffusion process for the reverse case. In future research of the Cd Te solar cell, such an approach may enable the determination of the boundary conditions for all doping profiles and computation of the conversion efficiency, etc.
