云南省丽江地区倾斜面太阳总辐射计算模型对比分析

介绍5种根据水平面太阳总辐射、直接辐射、散射辐射和太阳天顶角计算南向倾斜面太阳总辐射的数学模型。利用云南省丽江地区太阳辐射观测数据,计算南向纬度倾斜面太阳总辐射值,与同期纬度倾斜面太阳总辐射观测值进行比对,并以观测值为参考,对由5种模型计算的纬度面太阳总辐射值作统计分析。结果显示:5种南向倾斜面太阳总辐射计算模型均能较好地计算出丽江地区南向纬度面上的太阳总辐射值。其中,Hay模型最适合于在不区分天气状况的条件下使用,Ma-Iqbal模型最适合于应用在阴天和多云天气状况下,而晴天条件下则最好选用Muneer模型。     

垂直面太阳散射辐射计算方法研究

建筑设计必须考虑太阳辐射在建筑立面上的热作用,但气象台站仅观测水平面辐射数据,垂直面上的太阳辐射资料稀缺。为提出一种依据水平面辐射观测数据来计算垂直面散射辐射的方法,该文研究并建立辐射观测站,并进行长期辐射观测,积累了一定量的辐射数据。通过对垂直面上散射辐射主要影响因素的分析,提出基于晴空指数Kt和直射辐射与垂直面法线方向夹角φ的垂直面散射辐射计算方法。利用观测数据确定公式中的计算系数,并将该文研究提出的计算方法与国内外的5种太阳散射辐射计算模型进行比较分析。结果表明:1)该文提出的计算方法所需计算参数仅依据国内常规辐射观测数据即可。2)该方法能够实现对不同朝向垂直面散射辐射的计算。3)与国内外常用计算模型相比,该方法在不同天空晴朗度、不同朝向上整体精度更高。研究认为该文方法与国内气象部门的辐射观测数据相匹配,所需计算参数少、精度高、简单易用,可为建筑能耗计算和热环境分析提供新的垂直面散射辐射计算方法。     

基于天气分型的水平面总辐射及散射辐射建模分析

为获得无太阳辐射观测地区的水平面总辐射及散射辐射量提出一种组合模型。首先通过日照百分率将天气情况分成3类,在此基础上,探究总云量、气溶胶等气象环境因子对水平面总辐射的影响,构建水平面总辐射线性模型;其次,考虑不同天气类型下气象环境因子的特征,建立基于高斯过程回归（GPR）的散射比和散射系数模型,进而获得散射辐射量;最后,得到每种天气类型下最优水平面总辐射模型与散射辐射模型构成的组合模型。结果表明,所提组合模型可有效提高水平面总辐射与散射辐射的预测精度。     

低纬度地区水平面太阳辐射的直散分离模型研究

以中国低纬度地区水平面太阳总辐射的直散分离为研究对象,依据福建、广东、广西和海南等低纬度地区4个气象台站1971~2003年的水平面太阳总辐射和散射辐射实测气象数据,采用回归分析方法,建立大气散射透射比与晴空指数之间的回归计算模型。选取LiuJordan模型、Orglill模型和Erbs模型3种代表性分离模型与自建模型比较,结果表明,自建模型准确度最高。得出结论:大气散射透射比与晴空指数之间存在显著的负相关性,建立二者之间的回归模型可实现水平面太阳辐射的直散分离。     

日太阳散射辐射月均值的估算

建筑物空调系统的全年或季节能耗分析和太阳能系统的设计分析,需要已知太阳总辐射和散射辐射数据。我国大多数地区只有总辐射观测,没有直接辐射或散射辐射观测,因此需要有一种散射辐射的估算方法。根据全国8个典型城市的实测数据．分析了日散射辐射和日总辐射与日照时长的关系,分别建立了日散射月均值的多项式拟合模型。经过郑州地区数据的检验认为,模型有很好的拟合性能,该模型可以作为通用模型。     

硅电池辐照计非线性模型与散射模型的修订

文章针对高、低太阳辐照度情况下,硅电池辐照计测量数据失真,以及太阳散射辐照度计算模型中水平面与倾斜面太阳辐照度比值系数较为单一,不能满足多种天气情况下太阳散射辐照度的测量需求,提出了电压与非线性太阳辐照度计算模型的修订方法,以及适应多种天气情况的太阳散射辐照度修正系数的修订方法。实验结果表明,对于修订后的非线性太阳辐照度计算模型以及太阳散射辐照度修正系数得到的实验数据,其中,80%的实验数据的误差在±10%之间,因此,文章的模型和修正系数均比较合理,可适应多种天气情况,并提高了硅电池辐照计测量结果的可靠性。     

光伏发电功率预测斜面辐射组合模型的评估研究

光伏发电功率预测以准确、可靠的倾斜面太阳辐射量数据为基础。文章通过斜面辐射组合模型的计算,得到倾斜面太阳辐射量。为了分析不同辐射组合模型对光伏发电功率预测结果的影响,建立光伏发电功率预测模型,同时,选取3种典型直散分离模型和4种斜面辐射模型进行理论分析,并将上述模型分别组成12种斜面辐射组合模型,进行光伏发电功率预测。研究结果表明:含Liu-Jordan模型的组合模型的功率预测值与实测值更吻合,其中,Erbs+Liu-Jordan组合模型预测结果的准确度最高;阴雨天,利用King模型进行计算时,会发生地面反射辐射值估计结果偏高的现象,导致预测结果的准确性较低。     

3种斜面月平均总辐射模型评估及光伏阵列最佳倾角研究

为分析倾角变化对斜面辐射和光伏发电量(或效率)的影响,对武汉地区正南朝向斜面月平均总辐射计算方法和光伏阵列最佳倾角问题进行理论研究和探讨,并通过湖北省气象局多倾角光伏组件观测试验系统进行试验验证,结果表明:1)Hay模型最适合散射辐射较多的武汉地区斜面辐射计算;2)武汉地区固定式光伏阵列年最佳倾角理论值和实测值均为20°,该倾角年总辐射量相比水平面增加4.0%,而年发电量增加14.9%,最佳倾角安装下系统效率为86.1%,装机年发电量约1.02 k Wh/Wp;3)分冬/夏半年调整一次安装倾角,可使斜面年总辐射量增幅较大,冬/夏半年的最佳倾角理论值均小于实测值(45°/10°),该方式下年总辐射量相比于水平面增加7.5%,而年发电量增幅高达18.1%。     

任意方位倾斜面上的总辐射计算

一、前言 任意方位倾斜面上的总辐射,对于太阳能系统设计、效能估算以及复杂地形情况下的气候研究具有重要意义,而且也是建筑设计和光合潜力估算的基本依据。由于倾斜面的辐射观测不易大量进行,况且我国没有这方面的系统资料,因此,利用水平面上的相应资料进行计算是比较现实的方法。水平面上的总辐射只包括直接辐射和漫射辐射,而倾斜面上的总辐射除了以上两部分以外,还包括倾斜面所对地面反射到倾斜面上的一部分太阳辐射。直接辐射的正确计算固然是重要的,但是漫射辐射和地面反射也都占有相当大的比例。根据资料计算,北京地区水平面上多年平均漫射辐射与总辐射月总量的比值为0.43,而成都地区的个别月份     

辽河入海口地区倾斜面太阳辐射研究

文章利用在辽河入海口地区测得的太阳辐射数据,比较了现有的17个倾斜面太阳辐射计算模型在不同天气工况下的准确性。分析结果表明：阴天工况下Gueymard模型精度最高,其次是各向同性模型;多云工况下,Willmott模型与实测值较为吻合;晴天工况下,Reindl模型的综合表现状况最好;在不区分天气工况下,Willmott模型和Reindl模型的精度较高。同时,通过改写Reindl模型的各向同性组分建立新的计算模型,用实测数据分析在不区分天气条件下新模型的精度,结果显示新模型的计算精度明显提高。利用logistic函数建立小时散射辐射分数与小时晴空指数的关系,并采用新模型计算辽河入海口地区冬季不同倾斜面单位面积所接收的太阳辐照量,结果表明,对于冬季的辽河入海口地区,太阳能采集装置布置的最佳方位角为-20～30°、倾角为50～70°,总太阳辐射量最高可达1 200 MJ/m²。     

Quality control and estimation hourly solar irradiation on inclined surfaces in South Korea

The measured data of global solar irradiation on a horizontal surface, the number of bright sunshine hours, and the amount of cloud cover for major cities of South Korea, during the period (1986–2005) are analyzed. Quality controls tests were carried out to eliminate spurious data and inaccurate measurements resulting from the cosine response error of the pyranometers. Accordingly, in six locations of South Korea where hourly global solar irradiation is currently measured, the hourly global solar irradiation was calculated using two Sunshine Fraction Radiation Model (SFRM) and a Cloud Cover Radiation Model (CRM), were compared and analyzed. Data for Ulsan, where hourly global solar irradiation is not currently measured, can be calculated from the data of the six other locations. The total solar irradiation on horizontal surfaces is separated into the beam and diffuses components. Empirical correlations for estimating the diffuse solar irradiation incident on horizontal surfaces have been proposed. The purpose of our work consists of predicting the solar irradiation on inclined surfaces based on horizontal measurements. To reach this goal, two studies were performed. They consisted of quantifying the accuracy of various well-known models. The first type of models calculated diffuse horizontal irradiations from global ones and the second type computed global irradiations on inclined planes from diffuse and global components on a horizontal surface. The proposed model can provide an alternative to building designers in estimating the solar irradiation on inclined surfaces where only the horizontal measurements are available.     

Calculation of monthly mean solar radiation for horizontal and inclined surfaces

The use of daily rather than hourly time intervals in the calculation of the monthly mean values of solar radiation for both horizontal and inclined surfaces has for long been a desirable objective due to a reduction in the required computational effort and more general availability of daily data. This paper presents a method for such calculations, with bright sunshine hours and surface albedo being the only required input data. The incorporation of the effects of multiple reflection between the ground and atmosphere results in relationships used to calculate the diffuse and total solar radiation for a horizontal surface which are largely independent of season and location.The present paper shows that, despite the use of a daily time interval, the solar radiation incident on both horizontal and south-facing surfaces may be calculated with an accuracy generlly associated with instrumental measurements. This result is achieved without the necessity of arbitrarily varying the empirical coefficients to account for variations in climatological conditions at the stations being studied.     

A simple clear skies model for the luminous efficacy of diffuse solar radiation on inclined surfaces

In the present work we study the luminous efficacy of diffuse solar radiation incident on vertical surfaces for a clear sky and mean hourly values of diffuse irradiance and diffuse illuminance. We develop a model easy to use, similar to a model previously obtained for horizontal surfaces. To develop the present model for vertical surfaces we assume that the slope of the surface influences diffuse illuminance and diffuse irradiance in the same way. As a consequence of this hypothesis, the luminous efficacy of diffuse solar radiation is assumed to be the same for both horizontal and inclined surfaces.     

Computational derivation of irradiance on building surfaces: An empirically-based model comparison

Performance simulation applications require reliable information regarding the intensity of solar irradiance on arbitrarily oriented building surfaces in order to properly predict buildings' energy use or to configure building-integrated solar energy systems. Since measured irradiance databases typically include only horizontal irradiance values, solar radiation intensity on inclined surfaces must be computationally derived. In this context, the present paper compares six options to derive, from horizontal irradiance data, solar radiation intensity levels on inclined surfaces. To evaluate these options, simulated downward vertical irradiance on four orientations were compared with measurements obtained in Austria. Two options that use both global and diffuse horizontal irradiance values for sky radiance generation delivered slightly better results than the others, which require only global horizontal irradiance. However, the range of errors was rather high for all options. Even for the best-ranked option, no more than 64% of the results had a relative error of less than ±20%.     

An assessment of a revised Olmo et al. model to predict solar global radiation on a tilted surface at Beer Sheva,Israel

A model to convert horizontal solar global radiation to that on a tilted surface is presented. It is based upon a relatively simple model proposed by [Olmo FJ, Vida J, Foyo I, Castro-Diez Y, Alados-Arboledas L. Prediction of global irradiance on inclined surfaces from horizontal global irradiance. Energy 24 (1999) 689–704]., which requires only measurements of horizontal solar radiation but was found to produce significant errors when tested with data from another site. The present model assumes the availability of databases for at least two of the three solar radiation types, viz., global, beam and diffuse. The horizontal global radiation is converted to that on a tilted surface by applying the Olmo model to the diffuse component, whereas the beam component is converted by using the geometrical relationship between the two surfaces. The original Olmo anisotropic radiation correction factor is now assumed to be a function of sky conditions. The solar radiation databases were converted to subsets corresponding to clear, partially cloudy and cloudy sky based upon clearness index values. The three anisotropic correction factors were determined by fitting to a 12-months database. The present model was then tested by applying it to a second database consisting of 24-months not involved in the model development. It was found to give better results than three highly regarded more complex models.     

A note on diffuse solar radiation on a tilted surface

We are presenting a note on comparative study of diffuse component of solar radiation on tilted surface with different angle of inclination. The monthly mean daily diffuse radiation have been calculated on inclined surfaces from the data of horizontal surface using the Circumsolar and Isotropic model and the anisotropic model of Klucher and Hay at Lucknow (Latitude 26.75°, Longitude 80.85°), Uttar Pradesh, India. These calculated results are compared with our measured value. The comparison shows that Klucher model who considered the effect of cloudy sky conditions gives comparatively good estimations particularly at low inclination angles.     

A comparative study of solar irradiation models on various inclined surfaces for India

This paper presents a statistical approach for the estimation of the diffuse/global irradiation on various inclined surfaces from the measured data of horizontal surface. In fact diffuse solar radiation on an inclined plane consists of two components: sky diffuse radiation and reflected radiation from the ground. For analyzing estimation of the daily tilted sky diffuse component from the daily horizontal diffuse irradiance, we have considered six models Badescu, Circumsolar, Skartveit and Olseth, Hay, Klucher and Liu and Jordan (Isotropic). All these models except Badescu adopted the same methodology for estimating the ground-reflected radiation component, therefore, only sky diffuse component was analyzed at Lucknow (latitude 26.75°, longitude 80.50°), India location. Statistical analysis showed that the Skartveit and Olseth model gives good prediction for the low inclination angle however; Klucher model gave better performance for highly inclined south-facing surfaces. The Root Mean Square Errors (% RMSE) value varies from 3.45% to 24.15% except for Badescu and Circumsolar model which predict worse results. In general, Klucher’s model provides close agreement with the measurements.     

Study of models for predicting the diffuse irradiance on inclined surfaces

Solar irradiance data on various inclined surfaces at different orientations are important information for active solar-system analyses and passive energy-efficient building designs. In many parts of the world, however, the basic solar irradiance data for the surfaces of interest are not always readily available. Traditionally, different mathematical models have been developed to predict the solar irradiance on various inclined surfaces using “horizontal” data. Alternatively, the diffuse irradiance of a sloping plane can be calculated by integrating the radiance distribution generated with a sky radiance model. This paper presents the evaluation of two slope irradiance models, namely, the Perez point-source model (PEREZSIM) and the Muneer model (MUNEERSIM), and two sky-distribution models, namely, the Perez all-weather model (PEREZSDM) and the Kittler standard-sky model (KITTLERSDM). Three-year (1999–2001) measured average hourly sky radiance and horizontal sky diffuse irradiance data were used for the model assessment. Statistical results showed that all four models can accurately predict the solar irradiance of a 22.3° (latitude angle of Hong Kong) inclined south-oriented surface, indicating the good predictive ability for modelling an inclined surface with a small tilted angle. In general, the KITTLERSDM and PEREZSIM show the best predictions for vertical solar irradiance at this location, followed by the PEREZSDM, then the MUNEERSIM.     

Experimental testing of models for the estimation of hourly solar radiation on vertical surfaces at Arcavacata di Rende

More than 55,000 data of hourly solar radiation on a horizontal surface and on vertical surfaces exposed to the south, west, north and east, measured at Arcavacata di Rende (CS), were compared with hourly radiation data calculated by various calculation models.Erbs, Reindl et al. and Skartveit et al. correlations for the split of hourly global radiation in the diffuse and beam components were used together with the isotropic sky model and three anisotropic sky models.The agreement between experimental and calculated data is generally good.     

Measurements and predictions of solar radiation incident on horizontal surfaces at Santa Fe, Argentina (31° 39′S, 60° 43′W)

Measurements and predictions of solar radiation during a period of 10 years on horizontal surfaces at Santa Fe (31° 39′ S, 60° 43′ W), Argentina, reported as average daily global radiation for each month, are presented. Data are compared to those obtained with a previously published and verified model for computing solar radiation on horizontal planes at the earth's surface for cloudless sky days. Measurements show an important reduction of global radiation with respect to the cloudless sky model predictions for all months of the year. Conversely, averaged daily diffuse solar radiation calculated with Page's formula shows a small increment with respect to the predicted diffuse solar radiation for cloudless sky conditions. When direct solar radiation data, calculated from global and diffuse solar radiation values, are compared to theoretical prediction, a significant decrease is observed. This trend is similar to that obtained for global solar radiation.