Outdoor energy ratings and spectral effects of photovoltaic modules

A temperature and irradiance matrix of performance parameters of a photovoltaic (PV) module can be used to predict the energy produced by that module. The matrix of these parameters is usually obtained through a series of indoor current-voltage (I-V) measurements using temperature and irradiance controlled equipment. In the current work, a series of periodical (every 30 minutes) I-V curves were obtained with varying irradiance and temperatures under prevailing day-long outdoor test conditions over a year. The I-V curves thus obtained were translated to the reporting temperature-irradiance matrix conditions as required per IEC 61853 draft standard. The variation of spectrum of natural sunlight over a period of one year and its influence on the performance parameters of various technologies are presented. A thermal model to predict module temperature under MPPT condition is also presented.