Development of Optimal Tilt Angle Models of a Photovoltaic Module for Maximum Power Production: Ethiopia

Table 1

Summary of related previous works.

References	Model	Advantages	Disadvantages
[23]		(i) Latitude, diffuse fraction, and albedo parameters are considered (ii)anisotropic (peers model) was used	(i) Other isotropic and anisotropic models were not considered in the study; (ii) this model is not accurately applied to other location
[24]		(i) the main parameters are declination angle and latitude; (ii) simple for analysis due to the consideration of the isotropic model	(i) Seasonal variation of optimal tilt angle not considered; (ii) the diffused solar radiation was assumed isotropic (only isotropic model is used)
[25]	The optimal tilt angle proposed is 29.5 degree	(i) the optimal tilt angle is obtained for the study site; (ii) Reindel et al. model is used	(i) Other diffuse radiation evaluation techniques were not considered; (ii) the result of this study can not be equally applied as optimal value for different locations
[5]	The optimal tilt angle is 23.5^o	(i) the annual optimal tilt angle found is nearly equal to the study site latitude	(i) this optimal tilt angle could not be equally applied to a different latitude locations
[20]	The optimal tilt angles are 37 to 44^o (isotropic models) and 46 to 47^o (anisotropic models)	(i) the study location optimal tilt angles were found using both isotropic and anisotropic models	(i) the result is only applicable to the study site, no general model is suggested for other locations; (ii) no comparison of the result obtained by different models using statistical tools
[16]	Optimal tilt angles for Aligarh and New Delhi are 27.62^o and 27.95^o, respectively	(i) Annual optimal tilt angles of the study sites were determined; (ii) A simplified isotropic model was used; (iii) numerical values of the tilt angle were suggested	(i) Diffused radiation was assumed uniformly distributed; (ii) can not be accurately applied to other locations
[26]	Linear, second-order, and third-order polynomial models are proposed	(i) the optimal tilt angle was obtained by using hourly experimental solar radiation data; (ii) optimal tilt angles and the corresponding models were developed using an anisotropic model	(i) Other parameters such as latitude were not considered in the study