Abstract
With the growing demand of economically feasible, clean, and renewable energy, the use of solar photovoltaic (PV) systems is increasing. The PV panel performance to generate electrical energy depends on many factors among which tilt angle is also a crucial one. Among hundreds of research work performed pertinent to solar PV panels performance, this work critically reviews the role of tilt angles and particularly locating the optimum tilt angle using different methods. The past data collected for analysis can be categorized mainly into mathematical model based, experimental based, simulation based, or combination of any of these. Single-axis tracking, dual-axis tracking, simple glass cover, hydrophobic glass cover, soiled glass, clean glass, partial shadow, use of phase-change material, computational fluid dynamic analysis, etc., are the novel methods found in the literature for analysis and locating the optimum tilt angle. For illustration purpose, few figures are provided in which the optimum tilt angle obtained on monthly, seasonally, and annual basis is shown. Research works are growing in the field of computations and simulations using online software and codes. Pure mathematical-based calculations are also reported but the trend is to combine this method with the simulation method. As the PV panel performance is found to be affected by number of parameters, their consideration in any single study is not reported. In future, work is required to carry out the experiment or simulation considering the effect of soiling, glass material, temperature, and surrounding ambience on the location of optimum tilt angle. As a whole, the optimum tilt angles reported for locations exactly on the equator line, i.e., 0 degrees latitude, ranges between - 2.5 degrees and 2.5 degrees, for locations just above the equator line, i.e., latitude 2.6 degrees-30 degrees N ranges between 5 degrees and 28 degrees, for 40 degrees-70 degrees N, it is 29 degrees-40 degrees, and for 71 degrees-90 degrees N, it is 41 degrees-45 degrees. For locations at 2.6 degrees-30 degrees S, optimum tilt angles range between - 4 degrees and - 32 degrees, 30 degrees-46 degrees S, it is - 33 degrees to - 36 degrees, 47 degrees-65 degrees S, it is - 34 degrees to - 50 degrees, and for 66 degrees-90 degrees S it is - 51 degrees to - 62 degrees.