Dynamic thermal model of solar PV systems under varying climatic conditions

Abstract

The operating temperature of photovoltaic (PV) modules plays a central role in the photovoltaic energy conversion process, because the output voltage and, thereby, the produced output power decreases with increasing module temperature. The thermal response of PV modules is dynamic to changes in the climatic conditions affecting to the module. Therefore, a steady state model of module temperature cannot be justified.This paper presents a dynamic thermal model based on the total energy balance in the PV module. Main heat transfer mechanisms between the module and its environment have been modelled theoretical. The model is verified by the measurements data of the TUT solar photovoltaic power station research plant, which contains an accurate weather station, solar radiation measurements and a mesh of irradiance and module temperature measurements. A systematic sensitivity analysis of site-specific parameters was carried out to fine-tune the dynamic thermal model. The model was validated using time series of 1-s measurements data of three summer months and was found to differ less than 2°C from the measured module temperatures 80% of the time.