Transient thermal modeling and performance analysis of photovoltaic panels

Abstract

Photovoltaic technology enables the direct conversion of solar energy into electrical energy. Model studies have a very crucial place in the implementation of PV systems. Electrical efficiency decreases with increasing PV panel temperature. So, solar panel temperature is an important parameter that needs to be reduced to obtain a better energy efficiency from PV panels. In this study, the aim is to develop a simple method that can estimate the temperature of a solar panel. It can utilize different methods to obtain the thermal responses of a PV panel. In this study, a modeling study was carried out to find panel temperature, efficiency and power values under transient ambient conditions. As a simpler approach, “lumped system analysis” method was used. The model developed in this study can simulate the thermal performance of the PV panel under transient conditions. After the model is defined for a particular PV panel, the required inputs are; total incident solar radiation, wind speed and ambient temperature. The results obtained from this model were compared with existing modeling and experimental studies in the literature. With the simulation using the model developed in this study, panel efficiency, temperature and panel electricity power were calculated using instantaneous environmental data for the selected Konya and Sanliurfa (Turkey) regions. In this paper, it was obtained that the wind speed increased the PV panel efficiency, while the ambient temperature decreased it. Depending on the increase in wind speed (1–2 m/s), the increase in PV panel electric power is 3.7%, while the increase in high wind speeds (5–6 m/s) decreases to 0.77%. It was found that a 7°C increase in ambient temperature caused a 4°C increase in PV panel temperature and a 1.5% decrease in PV electrical power generation.

The PV panel electrical power values calculated using the efficiency values calculated according to the daily average environmental temperatures were found to be 13% higher than the power values calculated using instantaneous environmental temperatures. If this difference is not taken into account in the calculation of economic payback periods, it will lead to significant erroneous results. The importance of transient simulations of the PV panel has been demonstrated by the calculations.