Statistical comparison of monthly mean hourly and daily diffuse and global solar irradiation models and a Simulink program development for various Algerian climates M. Koussa * , A. Malek, M. Haddadi Renewable Energy Development Center, Postal Box 62, Observatory Road Bouzaréah, Algiers, Algeria article info Article history: Received 30 June 2008 Accepted 27 January 2009 Available online 12 March 2009 Keywords: Irradiation Diffuse Meteorological Bright sunshine hours Global abstract This work has two main objectives. The first objective is to carry out a statistical comparison of specific models for estimating monthly mean daily and hourly global and diffuse irradiations on a horizontal sur- face from the monthly average per day of the main meteorological data and to recommend the most accurate models to be used for estimating solar radiation in sites belonging to the Algerian climate areas represented by each of the three sites presented in this work. The second objective is to propose a Sim- ulink program where the methodology allows for reconstituting daily and hourly monthly mean horizon- tal solar radiation data. From the 10 global radiation models proposed in several journal papers, Rietveld’s, Garg et al.’s and McCulloch’s relations are retained, respectively, for estimating the monthly mean daily global ratio for Adrar, Bouzareah and Ghardaia sites and Page and from the nine retained dif- fuse relations, Page’s, Liu et al.’s and Erbs et al.’s relations are used, respectively, for the same sites for calculating the monthly averages per day of diffuse irradiation. On the other hand, the models of Jain and Liu et al. are, respectively, recommended for the reconstitution of the monthly averages per hour of the global and diffuse irradiations. However, the obtained results are used to develop a Simulink program which can be used in the estimation of long-term performance of flat plate solar radiation systems. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Data of global and diffuse solar radiation at a location are of sig- nificant use in the design and in the long-term evaluation of the so- lar energy conversion systems performances. Furthermore, monthly mean daily data are needed for the estimation of long- term solar systems performances, but for more precision and according to the considered system application, generally, scien- tists use the hourly data. Thus, for this, the required solar radiation component is the total solar irradiation incident on an inclined sur- face according to the slope of the considered sensor. If this compo- nent was not available, then, the horizontal global and diffuse radiation data are the best source of information for its calculation. However, measurements of the main meteorological parameters are generally available, but horizontal diffuse and global solar radiations are only measured at few locations due to the cost of the equipment required, and due to the care needed for regular adjustment to allow for the seasonal progression path of the sun across the sky, especially for the diffuse component measurement. This is the main case in Algeria where few of the 35 existing mete- orological offices record the solar radiation data. However, this paper has two objectives: the first consists in car- rying out statistical comparison of specific models for estimating the horizontal monthly mean daily and hourly of global and diffuse irradiations and retaining the most accurate models. The second one consists in developing a simple program in Simulink in which the retained models are used to reconstitute the monthly mean hourly and daily diffuse and global irradiations from the monthly average per day of a minimum main meteorological data. Many approaches have been proposed in several journals pa- pers and retained in our work to estimate monthly mean daily dif- fuse and global irradiations as function of the main meteorological data. On the other hand, some approaches have been used to ob- tain estimations of the monthly mean hourly global and diffuse irradiations from monthly mean daily data. Furthermore in our paper, we first performed a literature review of all the existing models and we made a description of each retained model. This was followed by a statistical comparison of the monthly mean daily and hourly retained models to the measured data obtained from three Algerian sites. 0196-8904/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.enconman.2009.01.035 * Corresponding author. Tel.: +213 021 90 15 03; fax: +213 021 90 16 54. E-mail addresses: mustaphakoussa@cder.dz (M. Koussa), amalek@cder.dz (A. Malek), mourad.haddadi@enp.edu.dz (M. Haddadi). Energy Conversion and Management 50 (2009) 1227–1235 Contents lists available at ScienceDirect Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman