Optimal tilt angle of a solar panel for a wide range of latitudes. Comparison between tilted and horizontal configurations

Abstract

The intensity of solar radiation incident on a flat surface is closely related to its angle of inclination. Therefore, optimal tilt angle (OTA) is needed to maximise this incident energy. However, the OTA depends on the latitude of the site and the period of year. This study proposes correlations that evaluate the optimum tilt angle (OTA) of a solar panel facing the equator. Four configurations were studied: monthly tilt angle (MTA), seasonal tilt angle (STA), annual tilt angle (ATA) and two-axis tracking system. Correlations are then proposed to evaluate these OTAs according to the latitude. Moreover, we show that the incident energy on a surface first increases by using ATA and then further improves by STA, then by MTA and finally by the two-axis tracking system. Furthermore, we compare two photovoltaic (PV) field situations whose modules are oriented towards the equator with a tilt angle of ATA and horizontal. The rows of tilted PV panels are spaced to avoid shading between them. Thus, it appears that the horizontal PV panels, which cover the entire ground surface, intercept more solar energy than the tilted one. The improvement reaches 8% at 10° of latitude and about 413% at 60° of latitude.