An investigation on the effect of operating temperature on power output of the photovoltaic system at University of Namibia Faculty of Engineering and I.T campus

Abstract

Sun hours is one of the parameters used in Photovoltaic system design in determining whether installation of a solar system would be recommended for a particular region, with a minimum of 5 sun hours per day being a recommended standard. As a result, photovoltaic systems are preferably installed in areas with long sun hours and these invariably have high temperatures. However, studies carried out on the performance of photovoltaic modules have shown a considerable decrease in their power output at temperatures above their optimum operating temperature 25°C. Most interestingly, research has also shown a decrease in the output power of a photovoltaic module as it cools down after being heated to 58°C indicating that high temperatures may cause premature aging of the module. This research aims to determine whether the temperatures at which University of Namibia (UNAM) Faculty of Engineering and I.T campus' photovoltaic modules are operated are high enough to reduce the module power output considerably. To achieve this, the average operating temperature of the systems modules for the period of 214 days between 1 March and 30 September 2014 was determined. During the course of the research it was discovered that 79% of the insolation received by the system's modules daily is received in the time period between 12 pm and 4 pm. In this report, this time period will be referred to as the peak insolation period and because the insolation received directly affects PV power output, particular attention was paid to the effect PV module operating temperatures have on the system power output during this period. The PV system was modeled to a 98.7% mean accuracy using Matlab Simulink and run at optimum operating temperature, daily average operating temperature and peak insolation period operating temperature, for a range of insolation values. The simulation results show a 0.31% decrease in system power output per Kelvin increase in temperature and performance ratios of 0.97 and 0.94 when the simulation is run at daily average temperature and average peak insolation period temperature respectively. Finally, using the T test at the 95% confidence level, the power outputs obtained when the simulation was run at average operating temperature and average peak insolation temperature were tested to see if they are statistically different from the power outputs obtained when it is run at optimum operating temperature. The results of the T test showed that the power outputs obtained at both the average operating temperature and the average peak insolation operating temperature are statistically different from the power output at optimum operating temperature indicating that the temperature significant decreases the PV system power output.