Photovoltaic array Reconfiguration of Maximum Power Transfer

Lew Andrew R. Tria

(MS Graduated: Summer 2009)

Abstract

Low efficiency and high cost of photovoltaic systems necessitate optimizing their performance. In addition, power mismatch is not uncommon in poorly designed photovoltaic systems. Several methods have been presented in past studies to get the maximum available power from a PV system, which include load matching, automated sun tracking and maximum power point tracking. In this paper, we developed a photovoltaic array reconfiguration algorithm to maximize the power that an array can provide a load. The algorithm reconfigures the array such that each element of the array is operated at its maximum power point. A switch topology was also designed to implement the algorithm using the maximum number of switches. Two parameters are used by the algorithm: array loaded voltage and temperature. The algorithm is tested on reconfiguring an array of four photovoltaic panels. The performance of the photovoltaic modules is studied with and without the switching algorithm. Simulations were also done to validate the performance of the system. Tests showed that for a constant resistance load, the algorithm can match the performance of other possible configurations and introduce a significant improvement in the output power of the array. For the constant current load, it was noted that the array can supply the required current at a minimum irradiance while for a constant voltage load, the system performed better than any of the possible configurations.

Subject Index : Photovoltaic power systems,