Performance Evaluation of 130kWp Grid-Tied PV Solar System with Snail Trail Affected PV Solar Panels /

Abstract

Defects in PV modules including snail trail effect might cause considerable performance degradation and should be identified and diagnosed early to avoid bigger system and financial losses. The purpose of this study is to evaluate the performance of a 130 kW grid-tied PV plant and analyze the effect of snail trail on its electrical performance. The 130kWp grid-tied PV solar system under investigation comprises of two plants and each plant has the capacity 65kWp. Plant-1 is affected by snail trail and the other is unaffected by such defect. Performance of the both plants is first evaluated with simulation software PVsyst, by using the rated technical specifications of the equipment installed at site. The simulated results of both the systems are then compared with the actual data collected from the site for the respective systems. The PV panels are then tested in lab at two different times, once in 2017 and a second time in 2021. Physical inspection, I-V curve tracing and EL testing as per IEC 61215 are conducted and compared with each other in order to study the difference in performance over time. The overall results show that the yeild of plant-1 has decreased more over four years as compared to plant-2 over the same period even though both the plants are installed in the same conditions. The comparison of the actual yield data of both plants with the simulated PV plant data shows that plant-2 performs better than that of plant-1 when compared with simulated data. Moreover, the analysis of actual plant data shows that in 2018 the yield reduces by 7.7% for plant-1 and 7.0% for plant- 2 with respect to yield in 2017. The lab test conducted show that the unaffected PV panel degraded from 241.94W in 2017 to 213.7W in 2021 with a degradation of 11.7% over 4 years, whereas the snail trail affected PV panel degraded from 213.1W to 154W with a degradation of 27.73% over 4 years. This study shows that there is a significant effect of snail trails on the power of the PV panels with large number of snail trails. The effect on the yield is not as much significant as the effect on the power on the tested panel as all PV panels are not affected by snail trails (164/260 are affected) and 73% of the affected PV panels only have 1-5 cells affected from snail trails. The analysis presented in this study will help researchers and designers in identifying the root cause of performance degradation of PV power plants due to snail trail defects.