PERFORMANCE ANALYSIS OF TRACKED PANEL ACCORDING TO PREDICTED GLOBAL RADIATION

In this paper, the performance of a south facing single-axis tracked panel was analyzed according to global radiation predicted by empirical model. Mathematic expressions appropriate for single-axis tracking system were derived to calculate the radiation on it. Instantaneous increments of solar energy collected by the tracked panel relative to fixed panel are illustrated. The validity of the empirical model to Taiwan area will also be examined with the actual irradiation data observed in Taipei. The results are summarized as follows: the gains made by the tracked panel relative to a fixed panel are between 20.0% and 33.9% for four specified days of year, between 20.9% and 33.2% for the four seasons and 27.6% over the entire year. For latitudes below 65°, the yearly optimal tilt angle of a fixed panel is close to 0.8 times latitude, the irradiation ratio of the tracked panel to the fixed panel is about 1.3, which are smaller than the corresponding values calculated from extraterrestrial radiation, suggesting us that the installation angle should be adjusted toward a flatter angle and that the gain of the tracked panel will reduce while it works in cloudy climate or in air pollution environment. Although the captured radiation increases with the maximal rotation angle of panel, but the benefit on the global radiation case is still not so good as that on extraterrestrial radiation case. The irradiation data observed is much less than the data predicted by the empirical model, however the trend of fitting curve to the observed data is somewhat in agreement with that to the predicted one; the yearly gain is 14.3% when a tracked panel is employed throughout the year.

[1]  A. Hepbasli,et al.  Determination of the optimum tilt angle of solar collectors for building applications , 2007 .

[2]  D. Ibrahim.  Optimum tilt angle for solar collectors used in Cyprus , 1995 .

[3]  Bin-Juine Huang,et al.  Feasibility study of one axis three positions tracking solar PV with low concentration ratio reflector , 2007 .

[4]  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 .

[5]  Mireia Diez,et al.  Solar radiation incident on tilted surfaces in Burgos, Spain: Isotropic models , 1995 .

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

[7]  H. Hottel.  A simple model for estimating the transmittance of direct solar radiation through clear atmospheres , 1976 .

[8]  M. Al-Akhras,et al.  Optimizing the tilt angle of solar collectors , 2002 .

[9]  Benjamin Y. H. Liu,et al.  The interrelationship and characteristic distribution of direct, diffuse and total solar radiation , 1960 .

[10]  Tian Pau Chang,et al.  The gain of single-axis tracked panel according to extraterrestrial radiation , 2009 .

[11]  Benjamin Y. H. Liu,et al.  The long-term average performance of flat-plate solar-energy collectors , 1963 .

[12]  Tin-Tai Chow,et al.  Numerical study of desirable solar-collector orientations for the coastal region of South China , 2004 .

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

[14]  J. I. Jiménez,et al.  Solar radiation on sloping surfaces with different orientations in granada, Spain , 1982 .

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

[16]  C. Y. Chan,et al.  An empirical approach to estimating monthly radiation on south-facing tilted planes for building application , 2006 .

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

[18]  Richard C. Neville,et al.  Solar energy collector orientation and tracking mode , 1978 .

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

[20]  V. H. Morcos.  Optimum tilt angle and orientation for solar collectors in Assiut, Egypt , 1994 .