ABSTRACT
Optimisation of an incident energy on a step tracking PV system with equatorial installation was considered in this study. Calculation of incident energy on the tilted P V array was conducted using a latitude and longitude of the installation and a 45-day average of the clearness index for Thailand's sky obtained from previous studies by others. A uniform sky was assumed and surrounding reflection was neglected. Two to six steps per day tracking modes were investigated. In each mode, optimisation of the incident energy was carried out to determine appropriate time and angle to adjust the array. The incremental energy obtained as compared to that of a fixed (and tilted) array was used as a criteria for optimum steps per day. The calculations were verified by field measurement of PV module short-circuit currents. Two sets of PV module were installed as the fixed and the two step tracking installations. A microprocessor-based data acquisition system was employed and data analysis was carried out on a personal computer. Result of the study shows that with two steps per day tracking, an increase in incident energy of 22 % is attainable. The energy increases as a number of step increases but the incremental is less.
