Optimum tilt angle of solar collectors and its impact on performance

Abstract

SYNOPSIS A solar collector collects maximum energy when solar radiation strikes its surface at a vertical angle of incidence. This leads to the concept of optimum tilt angle. This paper presents a novel and general calculation method of optimum tilt angle of solar collectors by means of a clear-day solar radiation model. The model includes optimum tilt angle as a yearly average, a half-yearly average for the summer months, and a half-yearly average for the winter months. Only longitude, altitude and nature of climate of any location are required as input parameters. Optimum tilt angles for 23 world cities are presented to illustrate the model. The model compares the impact of optimum tilt angle on the collection of solar radiation energy with that of the tilt angles commonly used. It was found that the tilt angle of solar collector equals optimum tilt angle ± 10° at a location is acceptable in practice since it results in the relative error of solar energy gain below 1.5%.