SUN-TRACKING MECHANISM USING EQUATORIAL AND ECLIPTIC AXES

The question of how to construct a sun-tracking structure for concentration photovoltaics is addressed. A new concept that uses, in addition to the familiar equatorial axis, a second axis perpendicular to the ecliptic plane, is proposed. With the approximation that the earth's orbit is circular, the required motion about both these axes is of constant velocity. However, the eccentricity of the earth's orbit introduces a tracking error of +/-2-degrees whose correction would require a small variation in the velocity of rotation about the ecliptic axis throughout the year. The foreseen advantage of the proposed system is the ease of control.