Solar Position Measurement System Utilizing Solar Cell Array

Abstract

This paper presents a novel approach for estimating the position of the sun by measuring the output voltage signals of two solar cell arrays orientated orthogonally to one another. Each array comprises a symmetrical arrangement of six cells inclined at angles of either 15, 45 or 75 to the horizontal, respectively. As the position of the sun varies over the course of the day, a change is induced in the output voltage of each of the solar cells within the array. It is shown that the output voltage of any cell (V) varies as a linear function of the included angle between it and the solar cell with the maximum output voltage (Vmax). A mathematical correlation is derived to express the relationship between the comparative output voltage of each solar cell (V/Vmax) and the solar position. The suns position is then computed by averaging the elevation angles derived from the comparative output voltages of all of the cells within the array. It is shown that both the zenith angle and the latitude angle of the sun can be accurately determined by deploying the measurement system such that one solar cell array is aligned in the East-West (E-W) direction while the other is orientated in the North-South (N-S) direction.