Correlations for estimating solar radiation using sunshine hours and temperature measurement in Osogbo, Osun State, Nigeria

Abstract

In this study, the global solar radiation on horizontal surface in Osogbo, Osun state, Nigeria was analyzed using 11-year data (1997–2007). Correlations using linear and quadratic expressions were developed to relate the global solar radiation on horizontal surface based on relative sunshine hours and temperature measurements for evaluating the monthly average daily global solar radiation. The calculated monthly clearness index values indicate that the prevailing weather condition in Osogbo is heavily overcast. All the developed quadratic correlations gave better correlation coefficients (0.834, 0.872 and 0.823 respectively) than the linear models. However, the Hargreaves and Samani related based quadratic model gave the best among the three developed quadratic expressions and is therefore suggested for estimating the monthly global radiation in this site and its surroundings.

Keywords

global solar radiation / Hargreaves model / sunshine hour / ambient temperatures / Osogbo

References

[1] Falayi E O, Adepitan J O, Rabiu A B. Empirical models for the correlation of global solar radiation with meteorological data for Iseyin, Nigeria. International Journal of Physical Sciences, 2008, 3(9): 210–216

[2] Augustine C, Nnabuchi M N. Relationship between global solar radiation and sunshine hours for Calabar, Port Harcourt and Enugu, Nigeria. International Journal of Physical Sciences, 2009, 4(4): 182–188

[3] Sambo A S. Solar radiation in Kano: A correlation with meteorological data. Nigerian Journal of Solar Energy, 1985, 4: 59–64

[4] Augustine C, Nnabuchi M N. Correlation between sunshine hours and global solar radiation in Warri, Nigeria. Pacific Journal of Science and Technology, 2009, 10(2): 573–579

[5] Augustine C, Nnabuchi M N. Empirical Models for the Correlation of Global Solar Radiation with Meteorological Data for Enugu, Nigeria. Pacific Journal of Science and Technology, 2009, 10(1): 693–670

[6] Chukwuemeka A, Nnabuchi M N. Solar radiation in Port Harcourt: Correlation with sunshine duration. Pacific Journal of Science and Technology, 2009, 10(1): 681–685

[7] Ogolo E O. Evaluating the performance of some predictive models for estimating global solar radiation across varying climatic conditions in Nigeria. Indian Journal of Radio & Space Physics, 2010, 9(3): 121–131

[8] Eze A E, Ododo J C. Solar radiation prediction from sunshine in Eastern Nigeria. Energy Conversion and Management, 1988, 28(1): 69–73

[9] Fagbenle R L. A comparative study of some simple models for global solar irradiation in Ibadan, Nigeria. International Journal of Energy Research, 1992, 16(7): 583–595

[10] Sambo A S. Empirical models for the correlation of global solar radiation with meteorological data for northern Nigeria. Solar and Wind Technology, 1986, 3(2): 89–93

[11] Hargreaves G, Samani Z. Estimating potential evapotranspiration. Journal of Irrigation Drainage Engineering (USA), 1982, 108(3): 225–230

[12] Chiemeka I U, Chineke T C. Evaluating the global solar energy potential at Uturu, Nigeria. International Journal of Physical Sciences, 2009, 4(3): 115–119

[13] Akpabio L E, Udo S O, Etuk S E. Modelling global solar radiation for a tropical location: Onne, Nigeria. Turkish Journal of Physics, 2005, 29(1): 63–68

[14] Fagbenle R L. Correlation of monthly mean diffuse solar radiation with sunshine duration in Ibadan, Nigeria. International Journal of Sustainable Energy, 1992, 13(3): 145–153

[15] Awachie I R N, Okeke C E. Solar radiation patterns during the harmattan season at Enugu, Nigeria. Energy Conversion and Management, 1985, 25(4): 487–490

[16] Ezekwe C I, Ezeilo C C O. Measured solar radiation in a Nigerian environment compared with predicted data. Solar Energy, 1989, 26(2): 181–186

[17] Medugu D W, Yakubu D. Estimation of mean monthly global solar radiation in Yola, Nigeria using Angstrom model. Advances in Applied Science Research, 2011, 2(2): 414–421

[18] Ideriah F J K. On the characteristic distribution of hourly diffuse and global solar radiation at Ibadan. Renewable Energy, 1992, 2(4-6): 461–468

[19] Abdulazeez M A, Ahmed A, Burari F W. The use of Factorial Design in the analysis of Global Solar Radiation in Nigeria. Archives of Applied Science Research, 2010, 2(5): 36–44

[20] Ododo J C. Prediction of Solar radiation using only maximum temperature and relative humidity: south-east and north-east Nigeria. Energy Conversion and Management, 1997, 38(18): 1807–1814

[21] Oldeman L R. Characterization of main experimental sites and sub-sites and questions of instrumentation. In: Bunting A H ed. Proceedings of Conference on Agricultural Environments. Characterization, Classification and Mapping. Rome, Italy, 1987, 101-112

[22] Adaramola M S. Estimating global solar radiation using common meteorological data in Akure, Nigeria. Renewable Energy, 2012, 47: 38–44

[23] World Meteorological Organization. Guide to Meteorological Instruments and Methods of Observation. 7th Edition, Geneva, 2008

[24] Chineke T C, Aina J I, Jagtap S S. Solar radiation database for Nigeria. Discovery and Innovation, 1999, 11(3,4): 207–210

[25] Akinnubi R T, Akinwale B F, Ojo M O, Ijila P O, Alabi O O. Characteristics variation of relative humidity and solar radiation over a tropical station Ibadan, Nigeria. Research Journal of Applied Sciences, 2007, 2(12): 1266–1269

[26] Udo S O. Contribution to the relationship between solar radiation and sunshine duration in the tropics: A case study of experimental data at Ilorin, Nigeria. Turkish Journal of Physics, 2002, 26(3): 229–236

[27] Igbal M. Prediction of hourly diffuse solar radiation from measured hourly global radiation on a horizontal surface. Solar Energy, 1980, 24(5): 491–503

[28] Dike V N, Chineke T C, Nwofor O K, Okoro U K. Evaluation of horizontal surface solar radiation levels in southern Nigeria. Journal of Renewable and Sustainable Energy, 2011, 3(2): 302–310

Acknowledgments

Thanks goes to Nigerian Meteorological Agency (NIMET), Oshodi, Lagos, Nigeria for providing data for this study.

Notation

a, b	Regression constants
ABS	Absolute value
H0	Monthly mean extraterrestrial solar radiation on horizontal surface/(MJ·m-2·d-1)
HGB	Gunn Bellanni reading/mm
Hpred	Estimated values of global solar radiation
Hobs	Measured values of global solar radiation
Hm	Measured monthly mean daily global solar radiation on a horizontal surface.
Isc	Solar constant (4.9212 MJ/(m2·d))
KT	Clearness index
MABE	Mean absolute bias error
MAPE	Mean absolute percentage error
MBE	Mean bias error
MPE	Mean percentage error
N	Day number ranging from n = 1 on 1st January to n = 365
\overline{n}	Monthly mean daily bright sunshine hours
\overline{N}	Maximum possible monthly mean daily sunshine hours
RMSE	Root mean square error
So	Measured values of monthly mean daily sunshine hours
S/So	Sunshine fraction
ΔT	Difference between the mean monthly maximum and minimum temperatures
Ta	Squared root of difference between the mean monthly maximum and minimum temperatures
δ	Solar declination
\varphi	Latitude of the site
{\omega }_s	Hour angle

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