Latitude Based Model for Tilt Angle Optimization for Solar Collectors in the Mediterranean Region

Abstract This paper inspects the different parameters that intervene in the determination of the optimal tilt angle for maximum solar energy collection. It proposes a method for calculating the optimal tilt angle based upon the values of the daily global solar radiation on a horizontal surface. A computer program using the mathematical model to calculate the solar radiation incident on an inclined surface as a function of the tilt angle is implemented. Four years data of daily global solar radiation on a horizontal surface in 35 sites in different countries of the Mediterranean region is used. The program assumes a due south orientation of the collectors and it determines the optimal tilt angle for maximum solar radiation collection for sites in the Mediterranean region. A regression analysis using the results of the computer simulation is conducted to develop a latitude based tilt angle optimization mathematical model for maximum solar radiation collection for the sites. We tested both a linear and a quadratic model (of the form ax2+bx) for representing the relationship between the annual optimal tilt angle and the site's latitude. The quadratic model is better; it provides very high prediction accuracy. 99.87% of the variation in the annual optimal tilt angle is explained by the variability in site's latitude with an average residual angle of only 0.96° for all 35 sites studied. It also gives an average percentage decrease in the annual solar radiation of only 0.016% when compared with actual optimal tilt angles.

[1]  Saiful Bari,et al.  Optimum orientation of domestic solar water heaters for the low latitude countries , 2001 .

[2]  Marwan M. Mahmoud,et al.  Determination of optimum tilt angle of single and multi rows of photovoltaic arrays for selected sites in Jordan , 1990 .

[3]  Hamdy K. Elminir,et al.  Optimum solar flat-plate collector slope: Case study for Helwan, Egypt , 2006 .

[4]  P. Koronakis,et al.  On the choice of the angle of tilt for south facing solar collectors in the Athens basin area , 1986 .

[5]  J. Dave,et al.  Validity of the isotropic-distribution approximation in solar energy estimations , 1977 .

[6]  J. Hay.  Calculation of monthly mean solar radiation for horizontal and inclined surfaces , 1979 .

[7]  M. Iqbal,et al.  Optimum collector slope for residential heating in adverse climates , 1979 .

[8]  N. Nijegorodov,et al.  Atmospheric transmittance models and an analytical method to predict the optimum slope of an absorber plate, variously oriented at any latitude , 1994 .

[9]  R. Tang,et al.  Optimal tilt-angles for solar collectors used in China , 2004 .

[10]  K. K. Gopinathan,et al.  Solar radiation on inclined surfaces , 1990 .

[11]  M. M. El-Kassaby,et al.  Investigation of a variable tilt angle Australian type solar collector , 1994 .

[12]  M. Kacira,et al.  Determining optimum tilt angles and orientations of photovoltaic panels in Sanliurfa, Turkey , 2004 .

[13]  W. Beckman,et al.  Evaluation of hourly tilted surface radiation models , 1990 .

[14]  Gilles Notton,et al.  PREDICTING HOURLY SOLAR IRRADIATIONS ON INCLINED SURFACES BASED ON THE HORIZONTAL MEASUREMENTS: PERFORMANCES OF THE ASSOCIATION OF WELL-KNOWN MATHEMATICAL MODELS , 2006 .

[15]  G. Kamali,et al.  Estimating solar radiation on tilted surfaces with various orientations: a study case in Karaj (Iran) , 2006 .

[16]  G. N. Tiwari,et al.  Optimization of Tilt Angle for Solar Collector to Receive Maximum Radiation , 2009 .

[17]  Ying-Pin Chang.  Optimal the tilt angles for photovoltaic modules in Taiwan , 2010 .

[18]  Ali Naci Celik,et al.  A critical review on the estimation of daily global solar radiation from sunshine duration , 2006 .

[19]  A. Q. Malik,et al.  Optimum tilt angle and orientation for solar collector in Brunei Darussalam , 2001 .

[20]  Moustafa M. Elsayed,et al.  Optimum orientation of absorber plates , 1989 .

[21]  H. Kambezidis,et al.  DIFFUSE SOLAR IRRADIATION MODEL EVALUATION IN THE NORTH MEDITERRANEAN BELT AREA , 2001 .

[22]  J. Kern,et al.  On the optimum tilt of a solar collector , 1975 .

[23]  M. Benghanem.  Optimization of tilt angle for solar panel: Case study for Madinah, Saudi Arabia , 2011 .

[24]  W. Beckman,et al.  Solar Engineering of Thermal Processes , 1985 .

[25]  M. M. El-Kassaby.  Monthly and daily optimum tilt angle for south facing solar collectors; theoretical model, experimental and empirical correlations , 1988 .

[26]  J. P. Chiou,et al.  Optimum slope for solar insolation on a flat surface tilted toward the equator in heating season , 1986 .

[27]  J. Bugler.  The determination of hourly insolation on an inclined plane using a diffuse irradiance model based on hourly measured global horizontal insolation , 1977 .

[28]  Kamal Skeiker,et al.  OPTIMUM TILT ANGLE AND ORIENTATION FOR SOLAR COLLECTORS IN SYRIA , 2009 .

[29]  D. Li,et al.  Determining the Optimum Tilt Angle and Orientation for Solar Energy Collection Based on Measured Solar Radiance Data , 2007 .

[30]  Gilbert M. Masters,et al.  Renewable and Efficient Electric Power Systems , 2004 .