Daily and Monthly Module Temperature Variation for 9 Different Modules

Abstract

One of the main parameter affecting the efficiency of PV modules is the module temperature. In this respect, outdoor testing of modules is very important to determine the temperature dependent performances and degradation rates. In this work, we analyzed the module temperatures of 9 different modules tested in the outdoor testing facility of METU-GUNAM, Ankara (latitude similar to 40 degrees N, in Central Anatolia and the climate is dry continental). The tested module types are two CIS (identical), one mu c-Si/a-Si, one Poly-Si, three Mono-Si (two identical), one HIT and one bifacial. The module temperatures can reach up to 76 degrees C while the ambient is around 39 degrees C during summer days. Monthly average module temperatures can reach up to 33.7 degrees C (CIS) while the monthly average ambient is at 26.0 degrees C and drops down to 1 degrees C while average ambient temperature is about the same as average module temperature. The results showed that the monthly averages of module temperatures differences are maximum during summer (similar to 3.5 degrees C) and minimum during winter (1.1 degrees C). It is interesting that the two CIS modules have the highest monthly average module temperature and although they are supposed to be identical their temperatures differ significantly. Bifacial and HIT module temperatures are lower than the Mono-Si modules. One of the two identical Mono-Si modules was not cleaned and its module temperature is always lower than the one that was cleaned periodically, as expected. In this work, we also present the results and discussions on the spatial variations of measured module temperatures of PV panels.