Improvement of Measurement of Diffuse Solar Radiation

Kasten, Fritz; Dehne, K.; Brettschneider, W.

doi:10.1007/978-94-009-7112-7_24

Cited by 19 publications

(15 citation statements)

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“…A drawback of the shadowring method is the use of correction factors to compensate the diffuse irradiance blocked by the shadowring [14,[18][19][20][21]. The correction most commonly used is based on the isotropy of the radiation, which depends on geometrical (the ring length and width) and geographical (latitude and solar declination) factors.…”

Section: Meo Shadowring Diffuse Measuring Methodsmentioning

confidence: 99%

“…Corrections based on anisotropic parameters such as atmospheric transmissivity K T (ratio of global to extraterrestrial radiation), zenital angle and turbidity atmospheric improve the precision of the shadowring diffuse irradiance [18] where the K T parameter is the best representative parameter of the anisotropic conditions of the sky [22]. So, K T corrections were proposed by Dal Pai [24] for particular K T intervals [28] and are similar to corrections found in the literature [18][19][20][21][22][23]. The effects of optical air mass are more significant for shorter time partitions.…”

Section: Instrumentation Quality Control Procedures and Statistical Ementioning

confidence: 99%

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Estimation of Hourly, Daily and Monthly Mean Diffuse Radiation Based on MEO Shadowring Correction

et al. 2014

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A statistical estimate model for the anisotropic diffuse fraction as a function of clearness index K T is proposed to estimate hourly, daily and monthly diffuse irradiations. Global, diffuse and direct solar irradiances were provided by the Laboratory of Solar Radiometry of Botucatu-UNESP (latitude 22.9º South, longitude 48.45º West, altitude 745 m). The period assigned for the study comprised the years 1996 to 2002. Global solar irradiance was measured by an Eppley PSP pyranometer, direct irradiance by an Eppley Nip pyrheliometer and diffuse irradiance by an Eppley PSP pyranometer under the Melo-Escobedo-Oliveira shadowring (radius of 40cm and width of 10cm). Isotropic and K T corrections were applied in diffuse irradiance. The proposed model was compared to classic models reported in the literature, with good results according to the MBE and RMSE statistical indicators for hourly, daily and monthly partitions, respectively. The results showed that the inclusion of K T correction improved the performance of the shadowring MEO according to MBE values for the three partitions: hourly, reduction from -7.21% to -1.74%; daily from -4.70% to 0.88% and monthly from -6.58% to -1.18%.

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Section: Meo Shadowring Diffuse Measuring Methodsmentioning

confidence: 99%

Section: Instrumentation Quality Control Procedures and Statistical Ementioning

confidence: 99%

Estimation of Hourly, Daily and Monthly Mean Diffuse Radiation Based on MEO Shadowring Correction

et al. 2014

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“…For the case of solar total irradiance measurements, reliable values of its diffuse component on a horizontal surface, I d , r , can be obtained from the measurements recorded using a shadow band, I d , u , as follows [ Batlles et al ., ]:

I_{d, r} = C \cdot I_{d, u}

where C is a factor that corrects for the diffuse radiation blocked by the band. For this spectral interval, the correction factor has been widely studied and quantified [ Drummond , ; Kasten et al ., ; Steven , ; LeBaron et al ., , ; Kudish and Ianetz , ; Batlles et al ., ; Muneer and Zhang , ].…”

Section: Methodsmentioning

confidence: 99%

Shadow‐band correction for diffuse ultraviolet radiation measurements

2013

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[1] Although the correction of shadow-band solar total diffuse measurements has been extensively studied, the case of diffuse ultraviolet measurements has not been properly addressed. This study analyzes the correction factor to be applied to experimental measurements performed adapting a shadow-band to a UV radiometer at a radiometric station in Badajoz (Spain). Three different models, based on approaches widely used for correcting total diffuse measurements, have been revised and adapted for the ultraviolet spectral range. Results reveal that some aspects of the correction proposed for total diffuse radiation are not suitable for ultraviolet diffuse radiation. The mathematical expressions are consequently modified to match the behavior in the ultraviolet range. Thus, three correction models particularized for ultraviolet diffuse measurements are proposed and validated against experimental data. The two models adapted from the original expressions proposed by Battles et al., and Steven show the best performance, with rRMSE of 2.74% and 2.20% and rMBE of 1.53% and 0.46%, respectively.Citation: Sa´nchez, G., A. Serrano, and M. L. Cancillo (2013), Shadow-band correction for diffuse ultraviolet radiation measurements,

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“…Different authors (Drummond, 1956;Painter, 1981;Kasten, 1983;Steven, 1984;Dehne, 1984;Stanhill, 1985;Pollard and Langevine, 1988;LeBaron et al, 1990;Kudish and Ianetz, 1993) have addressed the necessity of applying a correction factor. The accuracy of this correction is important since any subsequent calculation of the direct component is affected, particularly for high zenith angles.…”

Section: Introductionmentioning

confidence: 99%

“…Painter ( 1981) estimated the additional anisotropic correction by means of functions based on declination and clearness (the ratio of diffuse to global irradiante). Kasten (1983) developed an empirical model that uses cloudiness, turbidity, and declination parameters to characterize the sky conditions. Nevertheless, Dehne (1984) has observed that attempt to transfer these functions to other sites different than the ones for which they were derived were unsatisfactory.…”

Section: Introductionmentioning

confidence: 99%

96/00573 On shadowband correction methods for diffuse irradiance measurements

1996

Fuel and Energy Abstracts

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Abstract-Diffuse irradiance, G,, is an important variable in solar resource assessment. The diffuse irradiante can be worked out from global, G, and direct, Gb. irradiance measurements, but this method involves the use of relatively expensive tracking mechanisms. Alternatively, a widely accepted technique uses a pyranometer with a shadowband. Because the shadowband screens the sensor from part of the diffuse radiation coming in from the sky, a correction must be made to the measurements. However, because of the anisotropy of diffuse radiation it is difficult to compute an exact theoretical correction. In this study we use two data sets registered in two locations in Spain. The first one consists in coincident hourly values of global, direct, and diffuse irradiance; the latter by means of shadowband. The other data set includes the same variables but as 5-minute values. Our goal is to study the necessary correction factor for diffuse irradiance measurements obtained by means of shadowband. After testing several well-known correction methods, we have developed two different correction models, using two-thirds of the hourly data set, while the remaining one-third and the whole S-minute data set have been used for validation purposes. The last validation test suggests that our anisotropic models provide reliable corrections for conditions different than the ones where they have been developed. The results obtained by the developed models show a negligible mean bias deviation. Approximately 55% of cases present deviations lower than 5% over the mean value of diffuse h-radiance.

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Improvement of Measurement of Diffuse Solar Radiation

Cited by 19 publications

References 0 publications

Estimation of Hourly, Daily and Monthly Mean Diffuse Radiation Based on MEO Shadowring Correction

Estimation of Hourly, Daily and Monthly Mean Diffuse Radiation Based on MEO Shadowring Correction

Shadow‐band correction for diffuse ultraviolet radiation measurements

96/00573 On shadowband correction methods for diffuse irradiance measurements

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