Analyzing the Performance of Identical PV Modules in a Semi-Arid Region over a 2-year Period

Abstract

It is assumed that similar PV modules are expected to perform equally well under the same atmospheric conditions, especially with regard to their rated output power. However, this is not always the case due to a number of factors, which include cell degradation overtime and cell manufacturing. It has been reported that PV modules within arrays need to be identical. This is required to have equal currents flow through the branches of an array in order to prevent power mismatches, hot spots and a lower overall output power. The purpose of this paper is to analyze the performance of three identical 10 W PV modules which were used over a 2-year period in a semi-arid region, in order to identify any anomalies. An experimental research design is employed where three identical 10 W PV modules were each connected to its own power loads that were to extract more than 90% of the rated power of the module over a 2-year period. A data logging circuit is included that provides power conditioning between the PV modules and an Arduino UNO board, which serves as the data logger. This logger relays the measured data to LabVIEW where the processing, display and recording is done. Two key anomalies that were identified relate to the abnormal degradation in output power of one of the modules and the abnormal improvement in output power when a newly manufactured module is introduced into the system.